2nd Workshop of IGCP 609: Climate-environmental ... Sequence...Palynology and Genetic Sequence Stratigraphy of the Reservoir Rocks (Cenomanian, Bahariya Formation) in the Salam Oil

IGCP 609: Climate-environmental deteriorations during greenhouse phases: Causes and consequences of short-term Cretaceous sea-level change

and

EARTHTIME-EU Sequence Stratigraphy: Eustasy and sequence stratigraphy in the Cretaceous Greenhouse

Bucharest, 23rd – 25th August, 2014

http://www.univie.ac.at/igcp609/http://www.geoecomar.ro/website/igcp609/

ISBN 978-973-0-17266-9

2nd Workshop of IGCP 609: Climate-environmental deteriorations during greenhouse phases: Causes and consequences of short-term Cretaceous sea-level change

and

EARTHTIME-EU Sequence Stratigraphy Workshop: Eustasy and sequence stratigraphy in the Cretaceous Greenhouse

ABSTRACT VOLUME

Bucharest, 2014

Edited by Mihaela C. Melinte-Dobrinescu and Andrei Briceag

ISBN 978-973-0-17266-9

Printed by SmartPrint.ro

2nd Workshop of IGCP 609: Climate-environmental deteriorations during greenhouse phases: Causes and consequences of short-term

Cretaceous sea-level change

and

EARTHTIME-EU Sequence Stratigraphy Workshop: Eustasy and sequence stratigraphy in the Cretaceous Greenhouse

ABSTRACT VOLUME

Mihaela C. Melinte-Dobrinescu & Andrei Briceag (eds.)

Bucharest, 2014

ORGANIZING AND EXECUTIVE COMMITTEE:

Mihaela C. Melinte-Dobrinescu, National Institute of Geology and Geo-ecology (GeoEcoMar), Bucharest, Romania

Relu-Dumitru Roban, University of Bucharest, Faculty of Geology and Geophysics, Romania

Benjamin Sames, University of Vienna, Austria

Ismail Ömer Yılmaz, METU Middle East Technical University Ankara, Turkey

Michael Wagreich, University of Vienna, Austria

SCIENTIFIC COMMITTEE:

Bilal Haq (Washington DC, USA)

Xiumian Hu (Nanjing, PR China)

Julleh Jalalur Rahman (Dhaka, Bangladesh)

Mihaela C. Melinte-Dobrinescu (Bucharest, Romania)

Silke Voigt (Frankfurt, Germany)

Michael Wagreich (Vienna, Austria)

Ismail Ömer Yılmaz (Ankara, Turkey)

Svetlana Zorina (Kazan, Russia)

EDITORS:

Mihaela C. Melinte-Dobrinescu (Bucharest, Romania)

Andrei Briceag (Bucharest, Romania)

2nd IGCP 609: Climate-environmental deteriorations during greenhouse phases: Causes and consequences of short-term Cretaceous sea-level change Workshop and the EARTHTIME-EU Sequence Stratigraphy Workshop,

Bucharest, 23-25 August 2014

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TABLE OF CONTENTS Wagreich, M., Sames B. International Geoscience Program Project IGCP 609 and ESF Research Networking Program EARTHTIME-EU: Research into the Cretaceous World / 7

Chen, X., Wu, H., Kuhnt, W., Li, G. Orbitally Forced Sea-Level Changes in the Cenomanian-Turonian of the Tethyan Himalaya / 8

Conrad, C.P. The Solid Earth’s Influence on Sea Level / 9

Dinarès-Turell, J., Stoykova, K., Pujalte, V., Ivanov, M., Elorza, J. An Integrated Upper Maastrichtian Stratigraphic Record: Correlation of Basque and Bulgarian Sections and Implications for Global Sea-Level Trends / 10

Fauth, G., Bergue, C.T., Fauth, S.B., Vieira, C.E.L., Santos A.S., Ferreira, E.P., Viviers, M.C. The Upper Cretaceous Marine Ostracodes, Charophytes and Palynomorphs in Santos Basin, Brazil: an Integrated Biostratigraphic Study / 11

Gallemí, J. The Cretaceous Echinoids of Ormeniş (Brașov, Perșani Mountains, Eastern Carpathians): Systematics, Biostratigraphy and Palaeobiogeographic Significance / 12

Grabowski, J., Lakova I., Petrova, S., Schnabl P., Sobień K., Ivanova, D. Magnetostratigraphy, Magnetic Susceptibility and Calpionellid Stratigraphy of the Upper Berriasian in the West Balkan Mts., Bulgaria (Barlya Section) / 14

Haq, B. Inherited Landscapes and Sea-Level Change: As Exemplified by Cretaceous / 15

Hart, M.B., Leighton, A.D., Christopher W., Smart, C.W., Watkinson, M.P. The Cretaceous/Paleogene Boundary: Sea Level Change, Sequence Stratigraphy and the Timing of Key Events / 16

Hu, X. Tectonic and Climatic Control on Cretaceous-Paleogene Sea Level Changes in Northern Indian Margin (Tibetan Tethys Himalaya) / 17

Kopaevich, L., Nikishin, A., Gabdullin, R.,Yakovishina, E. Late Albian to Maastrichtian Sequences of Crimea Penninsula: Biostratigraphy, Sea Level Changes and Tectonostratigraphy / 19

Maurer, F., van Buchem, F.S.P., Dujoncquoy, E., Rameil, N. High Amplitude Cretaceous Sea Level Fluctuations Recorded in the Carbonate Systems of the Eastern Arabian Plate / 20



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Maurrasse, F.J.-M.R., Sanchez-Hernandez, Y. High-Resolution Chemostratigraphy and Facies Analysis of an Early Cretaceous Expanded Section of the Organyà Basin: Implications for Barremian-Aptian Global δ13C Correlation and Sea Level Changes / 21

Melinte-Dobrinescu, M.C., Briceag, A. Cretaceous Sea-Level Changes in the Southern Carpathians (Haţeg Basin, Romania) / 22

Michalík, J., Lintnerová, O., Soták, J., Boorová, D. Early Cretaceous Carbonate Platform Evolution in the Manín Pelagic Basin (Butkov Quarry, Central Western Carpathians, Slovakia) / 23

Mulayim, O., Mancini, A. E., Cemen, I., Yılmaz, O. I. Upper Cretaceous Rocks in the Cemberlitas Oilfield, (Adiyaman) Southeast Turkey, Northern Arabian Platform: Depositional Environment and Sequence Stratigraphy / 24

Olariu, C., Jipa, D.C., Steel, R.J., Ungureanu, C., Melinte-Dobrinescu, M.C. The Importance of Fractured Olistoliths and Shelf-Gravel Sorting for the Construction of a Tectonically-Controlled Carpathian Margin, Albian Bucegi Conglomerates, Eastern Carpathians, Romania / 25

Pavlishina, P. Palynology of the Albian – Cenomanian Boundary Interval in a Part of North Bulgaria / 26

Price, G.D. Dynamic Polar Climates in an Early Cretaceous Greenhouse World / 27

Rădan, S. Source to Sink Connection During Cretaceous: From Lateritic Crust to Related Sedimentary Deposits in Dobrogea (South-East Romania) / 28

Roban, R.-D., Melinte-Dobrinescu, M.C., Mitrică, D., Mihai, A., Krézsek, C. Mid Cretaceous Short-Term Orbital Cycles: The Eastern Carpathian Case Study / 29

Simmons, M.D. Cretaceous Eustasy: Industrial Perspectives / 30

Sprovieri, M. Astronomical Tuning of the Upper Albian – Lower Campanian: From Short to Very Long-Term Orbital Cycles / 31

Steel, R.J. Importance of Tidal Deposits in the Campanian Western Interior Seaway, USA / 32

Tahoun, S.S., Mohamed, O. Palynology and Genetic Sequence Stratigraphy of the Reservoir Rocks (Cenomanian, Bahariya Formation) in the Salam Oil Field, North Western Desert, Egypt / 33

Tüysüz, O., Yılmaz, I.O., Genç Ş. C., Özcan, E., Egger, H., Gallemí Paulet, J. A Climatic/Bio Event in the Cretaceous Palaeogene Boundary, Kocaeli Peninsula, NW Turkey / 34

Tüysüz, O., Melinte-Dobrinescu, M.C., Yılmaz, I.O. Cenomanian-Turonian Palaeogeography of the Pontides, Northern Turkey / 35



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Ţambrea, D., Dinu, C., Munteanu, I. Basin Subsidence and its Implication to Sedimentary Sequence Generation, Central Romanian Black Sea Offshore / 36

Wagreich, M., Sames, B., Lein, R. Limno-Eustasy – a Mechanism for Short-Term Eustatic Sea-Level Changes During the Cretaceous Greenhouse Climate / 38

Wan, X.,Wu, H., Xi, D. Earthtime China: Integrated Cretaceous Stratigraphic Time Scale of China / 39

Wendler, I. Challenges in Reconstruction and Global Correlation of Cretaceous Sea-Level Fluctuations / 40

Wendler, J.E. Sea Level – Evaluating the Pulse of the Earth System / 41

Wilmsen, M., Janetschke, N., Niebuhr, B. Sequence Stratigraphic Correlations Between Sedimentary Basins in Europe, Northern Africa and the Middle East: Implications for Amplitudes, Rates and Periodicities of Early Late Cretaceous Sea-Level Changes / 42

Wójcik-Tabol, P., Malata, E. Geochemical and Microfaunal Records of Environmental Changes in Flysch Sequences – A Case Study from the Barremian–Albian OC–Rich Deposits of the Silesian Nappe (Polish Outer Carpathians) / 43

Wolfgring, E., Wagreich, M. Palaeoenvironment and Biostratigraphy of Postalm-Section, Northern Calcareous Alps (Austria) / 44

Yılmaz, I. O., Hosgor, I. Records of Late Cretaceous Tectonically Enhanced Sequence Boundaries and Short-Term Sea Level Changes, SE Turkey, Arabian Platform / 45

Yılmaz, I. O., Altiner, D. Responses of Carbonate Platforms to Sea Level Changes: Examples to Eustatic and Tectonic Controls in Cretaceous Sea-Level Changes, the Central Tauride and Pontide Platforms / 46

Zorina, S.O. Modelling of Accommodation and Siliciclastic Sedimentation Mechanisms in Platformal Sedimentary Basins / 47



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INTERNATIONAL GEOSCIENCE PROGRAM PROJECT IGCP 609 AND ESF RESEARCH NETWORKING PROGRAM EARTHTIME-EU: RESEARCH INTO

THE CRETACEOUS WORLD Wagreich, M. & Sames, B.

University of Vienna, Department for Geodynamics and Sedimentology, A-1090-Vienna, Austria; e-mails: [email protected]; [email protected]

The recent rise in sea-level in response to increasing levels of atmospheric greenhouse gases and the associated global warming is a primary concern for society. Evidence from Earth’s history indicates that glacial-interglacial and some more ancient sea-level changes occurred at rates an order of magnitude or higher than that observed at present. To predict future sea levels we need a better understanding of the record of past sea-level changes. In contrast to glacial eustasy controlled mainly by waxing and waning of continental ice sheets, short-time sea-level changes during major greenhouse episodes of the earth history are known but still poorly understood. The global versus regional correlation and extend, the causes, and the consequences of these sea-level changes are strongly debated.

UNESCO IGCP 609 addresses correlation, causes, and consequences of significant short-term sea-level changes during the last major greenhouse episode of Earth history, the Cretaceous. 3rd to 4th order (kyr to a few Myr), sea level changes are recorded in Cretaceous sedimentary sequences. The mechanisms for these are controversial and include brief glacial episodes, storage and release of groundwater, regional tectonism, and mantle-induced processes.

Recent and on-going refinements of the geological time scale (GTS) using new radiometric dates and numerical calibration of bio-zonations, carbon and strontium isotope curves, paleomagnetic reversals, and astronomically calibrated time scales have made major advances for the Cretaceous. Major international efforts such as EARTHTIME, EARTHTIME-EU, EARTHTIME-CN and GTSnext programs are improving the Cretaceous time scale to yield a resolution comparable to that of younger periods of Earth history, such as the Neogene. The ESF Research Networking Program EARTHTIME-EU develops (i) a next generation fully integrated GTS, with unprecedented accuracy, precision, resolution, and stability for the last 100 million years by integrating independent dating techniques and full integration of various stratigraphic disciplines, and (ii) evaluates and tests scientific predictions arising from this improved GTS.

Based on the progress in the GTS, it is now for the first time possible to correlate and date short-term Cretaceous sea-level records with a resolution appropriate for their detailed analysis. Thus, IGCP 609 investigates sea-level cycles in detail in order to differentiate and quantify both short- and long-term records. The respective time interval includes the time of mid-Cretaceous hothouse conditions and the major oceanic anoxic events. Main goals are (i) to correlate high-resolution sea-level records from globally distributed sedimentary archives to the new high-resolution absolute time scale, using sea-water isotope curves and orbital (405, 100 kyr eccentricity) cycles; (ii) the calculation of rates of sea-level change during the Cretaceous greenhouse episode and evaluation of the role of feedback mechanisms; (iii) to investigate the relation of sea-level highs and lows to ocean anoxia, oxidation events and lake-level changes, and to evaluate the evidence for ephemeral glacial episodes or alternative climatic drivers.



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ORBITALLY FORCED SEA-LEVEL CHANGES IN THE CENOMANIAN-TURONIAN OF THE TETHYAN HIMALAYA

Chen, X.1, Wu, H.2, Kuhnt, W.3 & Li, G.4 1China University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, 29 Xueyuan Road, 100083 Beijing, China, e-mail: [email protected] 2China University of Geosciences, School of Ocean Sciences, 29 Xueyuan Road, 100083 Beijing, China, e-mail: [email protected]

3Christian-Albrechts-University, Institute of Geosciences, 14 Ludwig-Meyn Street, D-24118 Kiel, Germany, e-mail: [email protected]

4China University of Geosciences, School of Earth Sciences and Resources, 29 Xueyuan Road, 100083 Beijing, China, e-mail: [email protected]

Although data suggest elevated temperatures and high sea level in the Cenomanian-Turonian interval, rapid sea level changes possibly caused by polar ice growth and melting events were assumed (i.e., Gale et al., 2002; Miller et al., 2004). We have investigated the Cenomanian-Turonian marine strata of the Tethyan Himalaya tectonic zone. The biostratigraphy and isotope δ13C content of the Upper Cretaceous (mid Cenomanian-Maastrichtian) sediments within the studied area were initially established by Li et al. (2006) and Wendler et al. (2009). We undertook new studies of the planktonic foraminifers, carbon isotope stratigraphy as well as detailed sedimentary logging and sequence stratigraphic analysis on the Cenomanian as well Late Turonian-Early Coniacian interval. The C-isotopic events have been additionally correlated well with the ones given in the European reference curves.

The strata are mainly composed of marl and marly limestone couplets and thin bedded limestones. Based on the lithology features, microfacies, as well as physical and chemical proxies of the sea level changes (CaCO3 content, gamma ray log and magnetic susceptibility), the forth order and third order sequences have been identified. Based on these analyses, the relative sea level curve was estimated. Our work indicates that the sedimentary and carbonate content cycles are mainly controlled by global sea level changes. Spectral analysis of the carbonate content and natural gamma series reveals significant peaks with ratios of ~20 : 40 : 100 : 400, which matches well with Late Cretaceous orbital parameters. We therefore relate them to the eccentricity, obliquity and precession forcing. Four significant fast falling events in the Cenomanian and in the Late Turonian were identified, which correspond with the classic global sea level curves established in other continents (e.g. Sahagian et al., 1996; Haq, 2014). The effects of subsidence, sediment loading and thermal expansion in the study area can hardly lead to the abrupt and significant sea level falls. The only mechanism for the falling events is the growth of continental glaciers.

References

Gale, A.S., Voigt, S., Sageman, B.B., and Kennedy, W.J., 2008, Eustatic sea-level record for the Cenomanian (Late Cretaceous): Extension to the Western Interior Basin, USA. Geology 36, 859-862.

Haq, B. U., 2014. Cretaceous eustasy revisited. Global and Planetary Change 113, 44-58. Li, X., Jenkyns, H. C., Wang, C., Hu, X., Chen, X., Wei, Y., Huang, Y., Cui, J., 2006. Upper Cretaceous

carbon- and oxygen-isotope stratigraphy of hemipelagic carbonate facies from southern Tibet, China. Journal of the Geological Society, London 163, 375-382.

Miller, K.G., Sugarman, P.J., Browning, J.V., et al., 2004. Upper Cretaceous sequences and sea-level history, New Jersey Coastal Plain. GSA Bulletin 116, 368–393.

Sahagian, D., Pinous, O., Olferiev, A., Zakharov, V., 1996. Eustatic Curve for the Middle Jurassic–Cretaceous Based on Russian Platform and Siberian Stratigraphy: Zonal Resolution. AAPG 80, 1433-1458.

Wendler, I., Wendler, J., Gräfe, K.-U., Lehmann, J., Willems, H., 2009. Turonian to Santonian carbon isotope data from the Tethys Himalaya, southern Tibet. Cretaceous Research 30, 961-979



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THE SOLID EARTH’S INFLUENCE ON SEA LEVEL Conrad, C.P.

University of Hawaii, Department of Geology and Geophysics, 1680 East-West Road, Honolulu, HI 96822, United States, e-mail: [email protected]

Because it lies at the intersection of Earth’s solid, liquid, and gaseous components, sea level links the dynamics of the fluid earth with those of the solid earth. On timescales ranging from decades to millennia, the solid earth deforms both elastically and viscously in response to redistributions of hydrologic loads on the Earth’s surface, primarily associated with climate-induces changes in glaciation. These deformations induce spatial variations in rates of relative sea level change (measured relative to the ground surface), with amplitudes of several mm to cm per year. These sea level “fingerprints” are characteristic of (and may help identify) the deglaciation source, and carry significant societal importance because they will control rates of coastal inundation in the coming century. On longer timescales of millions to billions of years, convection of Earth’s mantle also supports long-wavelength topographic relief that changes as continents migrate and mantle flow patterns evolve. This changing “dynamic topography” causes m/Myr of relative sea level change, even along seemingly “stable” continental margins, that affects all stratigraphic records of Phanerozoic sea level. Nevertheless, several such records indicate sea level drop of ~230 m since a mid-Cretaceous highstand, when continental transgressions were occurring worldwide. This global drop results from several factors that combine to expand the “container” volume of the ocean basins. Most importantly, ridge volume decrease since the mid-Cretaceous, caused by a ~50% slowdown in seafloor spreading rate documented by tectonic reconstructions, explains ~250 m of sea level fall. These tectonic changes can be explained by a decline in the volume of volcanic edifices on Pacific seafloor, continental convergence above the former Tethys ocean, and the onset of glaciation, which dropped sea level by ~40, ~20, and ~60 m, respectively. These drops were approximately offset by an increase in the volume of Atlantic sediments and net seafloor uplift by dynamic topography, which each elevated sea level by ~60 m. Across supercontinental cycles, expected variations in ridge volume, dynamic topography, and continental compression together roughly explain observed sea level variations throughout Pangean assembly and dispersal. On the longest timescales that encompass Earth’s history, sea level may change as ocean water is exchanged with reservoirs stored by hydrous minerals within the mantle interior. Mantle cooling during the past few billion years may have accelerated drainage down subduction zones and decreased degassing at mid-ocean ridges, causing enough sea level drop to impact the Phanerozoic sea level budget. For all time-scales, future advances in the study of sea level change will result from im-proved observations of late-ral variations in sea level change, and a better under-standing of the solid earth deformations that cause them.

Fig. 1 - Solid earth mechanisms for long-term sea level change.



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AN INTEGRATED UPPER MAASTRICHTIAN STRATIGRAPHIC RECORD: CORRELATION OF BASQUE AND BULGARIAN SECTIONS AND IMPLICATIONS FOR GLOBAL SEA-LEVEL TRENDS

Dinarès-Turell, J.1 , Stoykova, K.2 , Pujalte, V.3, Ivanov, M.4 & Elorza, J.5 1Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, I-00143 Rome, Italy, e-mail: [email protected] 2Geology Institute Bulgarian Academy of Sciences, 24 G. Bonchev Str., 1113 Sofia, Bulgaria, e-mail: [email protected] 3 University of the Basque Country, Dept. of Stratigraphy and Palaeontology, UPV/EHU, PO Box 644, E-48080, Bilbao, Spain, e-mail: [email protected] 4Sofia University "St. Kliment Ohridski", Faculty of Geology and Geography, 15 Tsar Osvoboditel Blvd., 1000 Sofia, Bulgaria, e-mail: [email protected] 5University of the Basque Country, Dept. of Mineralogy and Petrology, UPV/EHU, PO Box 644, E-48080, Bilbao, Spain, e-mail: [email protected]

We present an integrated cyclo-magnetostratigraphy, nannofossil biostratigraphy, sequence stratigraphy and quantitative calcareous nannofossil study for the Upper Maastrichtian interval of two distant hemipelagic sections: Sopelana, Basque Basin and Bjala, Bulgaria. Both sections display similar rhythmic sedimentary successions imprinted by astronomical climate forcing (Milankovich cyclicity). The cyclo-magnetostratigraphy framework has been developed from the K/Pg (Cretaceous/Paleogene) boundary, within Chron C29r, down to the Lower/Upper Maastrichtian boundary, C31n-C31r. It encompasses a total of ~60 m in Sopelana and ~45 m in Bjala.

We integrate in the cyclostratigraphic framework the previously defined 3rd order depositional sequences in the studied sections (Pujalte et al., 1995; Baceta et al., 2004; Stoykova, Ivanov, 2002). This allow us to estimate the duration of the sequence stratigraphic units UMa-2, UMa-1 and Ma-Da, which appear to be strongly paced by the long-term 1.2 My obliquity amplitude modulating cycle (Dinarès-Turell et al., 2013). Finally, we have undertaken a quantitative nannofossil study to check additionally the sequence stratigraphic units UMa-2, UMa-1 and Ma-Da. It has been demonstrated by previous authors, that peaks in micro- and nannofossil abundance can be used to locate intervals of condensed sedimentation which, when integrated litho-log and lithofacies data, enable recognition and dating of maximum flooding surfaces. Conversely, abundance minima and changes in microplankton assemblage character have been associated with sequence boundaries. In this way, a stratigraphic framework has been established which aims to provide a nannofossil signature for each depositional sequence. This has been calibrated using low-latitude UC"TP" scheme of Burnett (1998), integrated with the Cretaceous Eustatic Cycle Chart of Haq (2014). References Baceta J.I., Pujalte V., Serra-Kiel J., Robador A, Orue-Etxebarria X., 2004. El Maastrichtiense final, Paleoceno

e Ilerdiense inferior de la Cordillera Pirenaica. In: Vera, J.A. (Ed.), Geología de España. Madrid, Sociedad Geológica de España, Instituto Geológico y Minero de España, p. 308–313.

Burnett, J.A., 1998. Upper Cretaceous. In: Bown, P.R. (Ed.), Calcareous Nannofossil Biostratigraphy. Brit. Micropal. Soc. Publ. Series. Chapman and Hall/Kluwer Acad. Publish., London, p. 132–199.

Dinarès-Turell J., Pujalte V., Stoykova K., Elorza J., 2013. Detailed correlation and astronomical forcing within the Upper Maastrichtian succession in the Basque Basin. Bol. Geol. y Minero 124, 2, 253–282.

Haq, B.U., 2014. Cretaceous Eustasy Revisited. Global and Planetary Change 113, 44–58. Pujalte V., Baceta J.I., Dinarès-Turell J., Orue-Etxebarria X., Parès J.M., Payros A., 1995. Biostratigraphic and

magnetostratigraphic intercalibration of Late Maastrichtian and Paleocene depositional sequences from the deep-water Basque basin, W Pyrenees, Spain. Earth and Planetary Science Letters 136, 17–30.

Stoykova K., Ivanov M., 2002. Event and sequence stratigraphy of the Maastrichtian and Danian in Bulgaria. Geologica Balcanica 32, 2-4, 55–61.



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THE UPPER CRETACEOUS MARINE OSTRACODES, CHAROPHYTES AND PALYNOMORPHS IN SANTOS BASIN, BRAZIL:

AN INTEGRATED BIOSTRATIGRAPHIC STUDY Fauth, G.1, Bergue, C.T.1, Fauth, S.B.1, Vieira, C.E.L.1, Santos A.S.1,

Ferreira, E.P.2 & Viviers, M.C.2 1Unisinos, Universidade do Vale do Rio dos Sinos, Instituto Tecnológico de Micropaleontologia, itt Fossil Av. Unisinos 950, 93022-000, São Leopoldo, RS, Brazil; e-mail: [email protected] 2PETROBRAS/Cenpes/BPA, Av. Horácio Macedo 950, 21941-915, Rio de Janeiro, RJ, Brazil

The offshore Santos Basin lies in the southeast portion of the Brazilian continental margin and its evolution is related to the breakup of western Gondwana. The oldest marine sedimentary sequence in this basin was deposited during the Aptian. The Santonian–Maastrichtian sequences here studied correspond to the drift phase and are characterized by a progradational trend which culminated in the Maastrichtian (Moreira et al., 2007). During this time, this sedimentary sequences were strongly influenced by the uplift of the Serra do Mar coastal mountain ranges. The ancestral Paraiba do Sul River tended to focus clastic influx into the northern and central Santos Basin during the Late Cretaceous and Paleogene (Modica and Brush, 2004). An integrated biostratigraphic study of the middle Santonian–upper Maastrichtian interval in the Santos Basin was carried out based on ostracodes, charophyte and palynomorph occurrences. The 2054 cutting samples from the 14 wells chosen for this study were dated according to palynological data. The faunal analysis revealed the occurrence of a rich marine (neritic) and non-marine (brackish-water) ostracode assemblages in most of the wells. Hundred nineteen species of ostracodes and 24 of charophytes were registered. Based on the distribution in time and space of those microfossils, four zones of non-marine ostracodes and two zones of charophytes were proposed. Though the Campanian registers global transgressive events, the Santos Basin has in this time interval paralic sedimentary deposits where the marine microfossils do not offer good biostratigraphic resolution. The present study, therefore, brings a contribution to more complete zonation for that section. The potential of the Cretaceous shelf marine ostracodes for correlation of sedimentary basins and the viability of paralic ostracodes and charophytes in coastal environments is highlighted.

References Modica, C.J., Brush, E.R., 2004. Postrift sequence stratigraphy, paleogeography, and fill history of the deep-water Santos

Basin, offshore southeast Brazil. AAPG Bulletin 88, 7, 923-945. Moreira, J.L.P., Madeira, C.V., Gil, J.A., Machado M.A.P., 2007. Bacia de Santos. Boletim de Geociências da Petrobras,

15, 531-549.



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THE CRETACEOUS ECHINOIDS OF ORMENIŞ (BRAȘOV, PERȘANI MOUNTAINS, EASTERN CARPATHIANS): SYSTEMATICS, BIOSTRATIGRAPHY

AND PALAEOBIOGEOGRAPHIC SIGNIFICANCE Gallemí, J.

Museu de Geologia de Barcelona-MCNB, Departament de Paleontologia, Parc de la Ciutadella s/n, 08003 Barcelona, Spain, e-mail: [email protected]

Introduction

Into a report of the Imperial Geological Institute dated May the 31st 1899, J. (Ion) Simionescu (1899a) presented his preliminary research on the fossils that F. Herbich had collected from the “Inoceramid marls at Ürmös” (= Ormeniş), on the eastern slope of the Perşani Mountains (central Carpathians). Simionescu provided a list of “identified forms that will be published in the Romanian Academy of Sciences” in which, apart from ammonites and bivalves (mainly inoceramids), two echinoids were mentioned: “Stenonia tuberculata Defr.” and “Cardiaster pseudo-Italicus n. f.” (op. cit., 231-232). Although Simionescu’s opinion was that the species represented the Turonian and Senonian stages, he pointed out that: 1) “Stenonia tuberculata appears very often at the Vicentin in the uppermost layers of the Scaglia, as well as in the Danian of Mancha Real (Spain)”, and 2) “At both localities, the former species appears in company of Cardiaster Italicus, a species very similar to the carpathian C. pseudo-Italicus”. Simionescu finally compared Ormeniş fauna with that of Glodu (Panaci, Suceava) studied by Athanasiu (1898): apart from several inoceramid species common to both localities, “two badly preserved echinoids very similar to [his] Cardiaster pseudo-Italicus” (op. cit., 232-233) were mentioned.

In fact, a single specimen of “Stenonia tuberculata Defr.” and three “Cardiaster pseudo-Italicus n. f.” from Ormeniş were fully described and illustrated later on (Simionescu, 1899b: 271-274; pl. 3, figs. 6, 7). The paper included several comments of the Danian age attributed to the former and to “Cardiaster Italicus” (a species very close to the latter) in the Southern Alps Scaglia and in Mancha Real (Spain).

Biostratigraphy

Walaszczyk & Szasz (1997) revised Herbich’s inoceramid faunas from Ormeniş, assigning them to the topmost Turonian-lowermost Coniacian (op. cit., fig. 2 and 785) in the Mytiloides scupini and the Cremmnoceramus rotundatus Zones, possibly extending into the C. deformis-C. crassus Zone).

Taxonomy and palaeobiogeography

The revision of the echinoids from Ormeniş described by Simionescu and kept in the Paleontology-Stratigraphy Museum belonging to the Faculty of Biology and Geology of the Babeş-Bolyai University at Cluj, has resulted in the validation of Stenonaster tuberculatus (Defrance, 1816) and the recognition of Rispolia subtrigonata (Catullo, 1827); “Cardiaster pseudo-Italicus” Simionescu, 1899 is synonymised to the latter.

Both species are characteristic of the Scaglia-like facies from their type localities in the Vicentino region (Southern Alps, Veneto, NE of Italy), the Djidde (= Cide) area (N Turkey), the southern Prepyrenees (NE of Spain) and the Betic Ranges (SE of Spain) in the northern side of the Western Tethys, to the Seybouse basin (NE Algeria) or near Tunis (N of Tunisia) in its southern side. They are generally associated to deep sedimentary beds (oceanic basins) without or with scarce terrigenous inputs.



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Rispolia subtrigonata was already quoted in SE Romania at Baia North Quarry (Gallemí et al., 2011, 49) together with inoceramid species representative of the so-called Cremnoceramus deformis-crassus Zone dating the uppermost Lower Coniacian.

Conclusions

The revision of the echinoids mentioned at Ormeniş, highlights their biostratigraphical significance and provides new information to establish both the depositional conditions of the “Inoceramid marls” of Ormeniş and the palaeogeographical connections with other Tethyan areas.

Acknowledgments

Thanks to Liana Săsăran (UBB, Cluj) for proving access to Simionescu's Ormeniş material and logistic support. This is a contribution to projects “Central Tethys” (Museu de Geologia de Barcelona-MCNB) and CGL2011-25581 of the Spanish Ministerio de Ciencia e Innovación.

References

Athanasiu, S., 1898. Studii geologice în districtul Suceava. Buletinul Societăţiĭ de Sciinţe din Bucuresci - România, Anul VII(1), 61-84 [In Romanian].

Gallemí, J., Lazăr, I., López, G., Martínez, R., 2011. The Turonian-Coniacian macrofaunal distribution in the Babadag Syncline (Northern Dobrogea, SE Romania) revisited. First results. Abstract Book, 8th Romanian Symposium of Paleontology (Bucharest, 29-30 September 2011), pp. 48-49.

Simionescu, J., 1899a. Ueber die ober-cretacische Fauna von Ürmös (Siebenbürgen). Verhandlungen der Kaiserlich-Königlichen Geologischen Reichsanstalt 8, 227-234.

Simionescu, I. 1899b. Fauna cretacică superióră de la Ürmös (Transilvania). Academia Română, Publicaţiunile Fondului Vasilie Adamachi 4, 237-274, pls. 1-3 [In Romanian].

Walaszczyk, I., Szasz, L., 1997. Inoceramid bivalves from the Turonian/Coniacian (Cretaceous) boundary in Romania: revision of Simionescu's (1899) material from Ürmös (Ormeniș), Transylvania. Cretaceous Research 18, 767-787.



14

MAGNETOSTRATIGRAPHY, MAGNETIC SUSCEPTIBILITY AND CALPIONELLID STRATIGRAPHY OF THE UPPER BERRIASIAN IN THE WEST

BALKAN MTS., BULGARIA (BARLYA SECTION) Grabowski, J.1, Lakova I.2, Petrova, S.2, Schnabl P.3, Sobień K.1 & Ivanova, D.2

1Polish Geological Institute – National Research Institute, Rakowiecka 4, 00-975 Warszawa, Poland, e-mail: [email protected]; [email protected] 2Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 23, 1113 Sofia, Bulgaria, e-mail: [email protected], silviya_p@geology/bas.bg, [email protected] 3Institute of Geology of the Academy of Sciences of the Czech Republic, v.v.i., Rozvojová, 269, 165 000 Praha 6, Czech Republic, e-mail: [email protected]

The section Barlya in the West Balkan Mts. of Bulgaria is located at 2 km east of the Bulgarian – Serbian border. Continuous carbonate pelagic succession from Oxfordian to mid-Berriasian crops out. It is concordantly covered by the hemipelagic clayey limestone – marl alternation of the Salash Formation, (late Berriasian to Hauterivian, Lakova et al. 1999). The lower part of Salash Formation, about 37-38 m thick, is the subject of this study. The section has been measured and sampled jointly for calpionellid biostratigraphy and magnetostratigraphy. The average sampling interval is between 0.5 and 1.0 m. Calpionellid biostratigraphy. The investigated lower 38 m of the Salash Formation have been assigned to the Elliptica, Simplex, Oblonga, Murgeanui and Darderi Subzone. The whole upper Berriasian Calpionellopsis Zone is documented along with the Berriasian/Valanginian boundary strata, i.e. the base of Calpionellites Zone (Darderi subzone). Several calpionellid bioevents are recorded: the mass occurrence of Tintinnopsella carpathica large variety; the successive first occurrences of Remaniella cadischiana, Calpionellopsis simplex, Calpionellopsis oblonga, Remaniella filipescui, Praecalpionellites murgeanui and Calpionellites darderi. These calpionellid bioevents, as well as the subzonal lower boundaries, are here directly confronted to the magnetic polarity chrons and the magnetic susceptibility fluctuations. The calcareous dinocysts Stomiosphaerina proxima and Stomiosphaera wanneri occur throughout the section studied. The first occurrence of Colomisphaera conferta is recorded in the topmost part of Oblonga Zone. Magnetostratigraphy and magnetic susceptibility. Magnetozones between the uppermost part of M17r and M14r were identified in the section. Boundaries between calpionellid zones are situated in the following magnetozones: Elliptica/Simplex – in M16r, Simplex/Oblonga – in the lower part of M16n, Oblonga/Murgeanui – at the top of M15n, Murgeanui/Darderi (Berriasian/Valanginian boundary) – in the lower part of M14r. Magnetic susceptibility (MS) reflects detrital influx of fine clay particles which is evidenced from good correlation between MS and K and Th from the gamma ray spectroscopy. MS reveals a well defined increasing trend starting in the lower part of M16n, close to the Simplex/Oblonga boundary. The highest MS values are observed already in the Lower Valanginian in M14r. The trend correlates well with the sea-level regression curve which culminates in the Early Valanginian (Haq 2014). Small variations on the MS curve might reflect short term sea-level changes. However, increase of terri-genous influx might be partially related also to the climate humidity increase which is well documented in the Western Tethys area in the Late Berriasian and Early Valanginian (Morales et al., 2013). Investigations were financially supported by the project DEC-2011/03B/ST10/05256 of the National Science Centre, Poland.

References

Lakova, I., Stoykova, K. and Ivanova, D., 1999. Calpionellid, nannofossil and calcareous dinocyst bioevents and integrated biochronology of the Tithonian to Valanginian in the Western Balkanides, Bulgaria. Geologica Carpathica 50, 131–168.

Morales, C., Gardin, S., Schnyder, J., Spangenberg, J., Arnaud-Vanneau, A., Arnaud, H., Adatte, T., Föllmi, K.B., 2013. Berriasian and early Valanginian environmental change along a transect from the Jura Platform to the Vocontian Basin. Sedimentology 60, 36-63.

Haq, B.U., 2014. Cretaceous eustasy revisited. Global and Planetary Change 113, 44-58.



15

INHERITED LANDSCAPES AND SEA-LEVEL CHANGE: AS EXEMPLIFIED BY CRETACEOUS

Haq, B.1,2 1NSF, Washington DC, USA; e-mail: [email protected] 2University Pierre and Marie Curie, Paris, France

Stratigraphic appraisal of sea-level change is normally undertaken along continental margins or in the interior basins. Geodynamic lithospheric modeling of these areas have had parallel but separate history for over three decades, leading to many controversies in the study of Eustasy.

More recently evidence has accumulated that indicates an intimate coupling between deep Earth and surface processes on the inherited landscape. This has led to new insights on how stratigraphic measures on continental margins can be influenced by mantle-driven long and short wavelength vertical lithospheric movements and brought a new understanding of the reasons for variance between empirical data and geodynamic models. Thus, we are at a stage where the views of stratigraphers and geodynamicists are converging to a consensus in these two important fields of geosciences.

Various solid earth processes and their implications for the stratigraphic record, especially as it is preserved on continental margins will be examined, using a recent worldwide synthesis of stratigraphic data that led to an updated eustatic history of the Cretaceous.

Cretaceous is known to have been a period of relatively warm climates with no northern hemispheric ice caps (and only ephemeral ice on Antarctica) and thus the tectonic models can be tested without the complications of an ice cover in at least one hemisphere. The sea-level record will be compared to tectonic forcings and the issue of solid-earth influences on eustasy at various temporal scales will be reviewed. Both horizontal and vertical motions of the lithosphere as well as global tectonics in the Cretaceous are shown to influence far-field landscapes that may in turn affect both regional (eurybatic) as well as global (eustatic) measures of sea level change.



16

THE CRETACEOUS/PALEOGENE BOUNDARY: SEA LEVEL CHANGE, SEQUENCE STRATIGRAPHY AND THE TIMING OF KEY EVENTS Hart, M.B., Leighton, A.D., Christopher W., Smart, C.W. & Watkinson, M.P.

School of Geography, Earth & Environmental Sciences, Plymouth University, Drake Circus, Plymouth PL4 8AA, United Kingdom; e-mail: [email protected]

The Cretaceous/Paleogene boundary, which is defined (GSSP, El Kef, Tunisia) by the first “evidence” of the Chicxulub impact, remains a problematic event in Earth history. Distal sites (e.g., El Kef, Gubbio, Stevns Klint) record the iridium ‘spike’, loss of carbonate sedimentation and biotic change compressed into very thin sedimentary successions. Proximal sites (e.g., Alabama, Texas and Mexico) have more complex sedimentary successions, created by seismic disturbance, the tsunami and post-impact instability. These successions are very different in appearance, with the presence of re-worked spherule beds and no iridium ‘spike’. In oceanic settings (e.g., Blake Nose, Demerara Rise) there is a sedimentary record that partly reflects both the proximal and distal successions, but at these locations the single spherule bed is graded and, therefore, in-situ.

In distal sites, such as Stevns Klint (Denmark), sea level changes and the resulting sequences can be determined, providing the background pattern of eustatic change well away from the Chicxulub impact site. Many of these sea level changes are thought to be relatively small in the Maastrichtian as evidenced by the presence of sea grass communities in the Maastricht Chalk of the Netherlands. These sea grass meadows can only survive by remaining within the photic zone and would have been adversely affected by significant sea level changes.

The arrival of impact products (ejecta particles, shocked quartz, iridium, etc.) interrupts these longer-term sequences, as would be expected from a sudden, unpredicted event. Their record in the sedimentary succession might be regarded as a ‘forced regression’ although it must be accepted that it will not fit into a normal sequence stratigraphy. In the earliest Paleocene sea level changes and the resulting sequences indicate a return to normal depositional patterns.

The use of precessional cycles in both the uppermost Maastrichtian and the lowermost Paleocene provide a time-scale for the determination of the biotic extinctions and the subsequent recovery, as well as the sedimentological events recorded in both the proximal and distal areas. Extinction to recovery in the earliest Paleocene appears to be 80–100 kyrs, based on the Brazos River area of Texas and in mid-Alabama. Sedimentological patterns returned to ‘normal’ in something less than this time interval. These time-scales are important as one has to incorporate the events associated with the emplacement of the Deccan volcanics into the sequence of K/Pg boundary events (extinctions, ocean acidification, etc.).



17

TECTONIC AND CLIMATIC CONTROL ON CRETACEOUS-PALEOGENE SEA LEVEL CHANGES IN NORTHERN INDIAN MARGIN

(TIBETAN TETHYS HIMALAYA) Hu, X.

Department of Earth Sciences, Nanjing University, Nanjing 210023, P.R. China, [email protected]

Detailed stratigraphical and sedimentologcial analysis allow to establish relative sea level changes in northern Indian margin (Tibetan Tethys Himalaya) during Cretaceous-Paleogene. Several major sea-level events and stages can be recognised:

1) Sea-Level Event 1 - Late Albian transgression. This transgression marked the transition from the Lower Cretaceous volcaniclastic sedimentation (Wolong Volcaniclastics) to pelagic marls/limestone/shales at the time of planktonic foraminifera Rotalipora subticinensis Subzone, ~102 Ma. This transgression happened along the northern margin of Greater India from Zanskar to Nepal and further to southeastern Tibet, and was interpreted as the results of passive margin thermal cooling related to final breakup of the East Gondwana (Hu et al., 2010).

2) Stable Stage 1: During Late Albian-Santonian (Gambacunkou Formations), the Indian block drifted away from south high latitude to medium latitude, where the northern Indian margin deposited mainly calcareous shales, marls and carbonates with increasing contents of carbonate up the sections. Besides variations in lithology related to the location of river mouths and climatic zonation (progressively higher southern- hemisphere paleolatitudes from west to east), Late Albian-Santonian successions compare closely from Zanskar to South Tibet.

3) Sea-Level Event 2 - latest Cretaceous-earliest Paleocene regression. A hiatus corresponding to most of the Campanian was found in Tibetan Tethys Himalaya. In Tingri, the overlying Zhepure Shanpo Formation and Jidula Formation show a shallowing-upward sequence with hyperpycnal flows or storm-surge turbidites with wave-reworked tops in lower part to deltaic and coastal environment in upper part (Jidula). In Gamba area, the Zhongshan and Jidula Formations record an overall shallowing-upward trend from mixed siliciclastic–carbonate rocks deposited in offshore environments to shallow-marine carbonates and coastal sandstones. This regression was interpreted to the response to the Deccan mantle doming when Indian block passed through this hot-spot (Garzanti and Hu, 2014).

4) Stable Stage 2: During the Paleocene, a carbonate ramp slowly established along the northern Indian margin (lower part of the Zongpu Formation). Overall, this stages shows a deepening trend starting in high-energy shoals with ooid bars at the lower part, low-energy protecting lagoonal areas, high-energy rhodolid bars and shoals in the middle, slowly changing into to open marine below wave base near the top (Hu et al., 2012) .

5) Sea-Level Event 3- Paleocene-Eocene boundary regression. This regression is testified by the occurrence of carbonate conglomerates as well as microfacies from open marine to lagoonal environment. This abrupt sea-level event is interpreted to represent the response to onset of the India-Asia continental collision. At that time, Tingri-Gamba area was suggested to be situated near tectonic foreland forebulge documenting a tectonic uplift which resulted in this regression (Li et al., submitted).

6) Stable Stage 3: During the Early to Middle Eocene, another carbonate ramp established in Tingri-Gamba area (upper part of the Zongpu Formation) showing deepening trend from lagoonal to open marine environments. These environments can be extended into Lutetian (SBZ10 to SBZ12, ~51-48 Ma).

7) Sea-Level Event 4 - Early Eocene carbonate ramp drowning (transgression). This transgression is evi-denced by a hardground between the topmost of the Zongpu and the Enba greenish marl. This carbo-nate ramp drowning is related to foreland subsidence (forebulge-foredeep transition) (Hu et al., 2012).



18

8) Stable Stage 4: During Middle Eocene when Enba and Zhaguo deposited, the Tingri-Gamba area

would represent a foredeep basin depositing in a storm-affected deltaic environment connected to the deforming thrust wedge to the north. After that, the Tingri-Gamba area was uplifted and became part of the Himalayan orogenic belt.

References

Garzanti, E., Hu, X., 2014. Latest Cretaceous Himalayan tectonics: Obduction, collision or Deccan-related uplift? Gondwana Research, doi.org/10.1016/j.gr.2014.03.010.

Hu, X.M., Sinclair, H.D., Wang, J.G., Jiang, H.H., Wu, F.Y., 2012. Late Cretaceous-Palaeogene stratigraphic and basin evolution in the Zhepure Mountain of southern Tibet: implications for the timing of India-Asia initial collision. Basin Research 24(5), 520-543.

Hu, X.M.A., Jansa, L., Chen, L., Griffin, W.L., O'Reilly, S.Y., Wang, J.G., 2010. Provenance of Lower Cretaceous Wolong Volcaniclastics in the Tibetan Tethyan Himalaya: Implications for the final breakup of Eastern Gondwana. Sedimentary Geology 223(3-4), 193-205.



19

LATE ALBIAN TO MAASTRICHTIAN SEQUENCES OF CRIMEA PENNINSULA: BIOSTRATIGRAPHY, SEA LEVEL CHANGES AND TECTONOSTRATIGRAPHY

Kopaevich, L., Nikishin, A., Gabdullin, R. & Yakovishina, E.

Lomonosov Moscow State University, Faculty of Geology, Vorobievy Gory, Moscow State University, Faculty of Geology, 1199234 Moscow, Russia; e-mails: [email protected]; [email protected]: [email protected]; [email protected]

The Upper Albian-Maastrichtian deposits of Crimea comprise around 700 meters mainly composed of car-bonate sediments. Diagnostic fauna are confined to a few levels: ammonites for Late Albian – Cenomanian interval; inoceramids for the Coniacian stage; ammonites and belemnites for the Campanian-Maastrichtian interval. The Late Santonian has been dated by the crinoid taxa Uintacrinus and Marsupites. Microfossils are quite abundant in the Crimean Albian-Maastrichtian rocks. To determine the age of the sediments, the planktonic foraminifer zonation has been used (Kopaevich, 2010). The Late Albian-Maastrichtian deposits are part of the sedimentary cover of the Cimmerian mountain-folded structure of Crimea.

In this sedimentary cover, Albian, as well as the Cenomanian up to Maastrichtian megasequences have been evidenced. The Albian sediments form an almost continuous cover and are characterized by a transgressive system tract (TST). Infilled erosional paleovalleys are seen at the base of the Late Albian sequences. The Upper Albian formations comprise Transgressive System Tract (TST) and High Stand System tract (HST). An erosional surface is present between the Late Albian and the Early Cenomanian. It is likely that this sedimentary unit was formed synchronously with volcanism and normal faulting. The Cenomanian-Maastrichtian sequence consists of neritic planktonic limestones and marls. Within this megasequence two subdivisions can be recognized: the Cenomanian-Santonian and Late Santonian-Maastrichtian. The first subdivision forms the regional cover, 100-150 m in thickness. The Upper Cenomanian deposits include a horizon with volcanic ashes up to 2-3 cm thick (Nikishin et al., 2013); a mid-Cenomanian non-sequence is also present. Within the SW Crimea, the Cenomanian comprises three full sequences of 3rd and 4th order, and the fourth one corresponds to the Cenomanian-Turonian boundary interval (Gale et al., 1999). At the end of the Cenomanian, a layer of “black shales”, up to 1 m thick, was deposited, with TOC content up to 5-8%. A regional sedimentation hiatus has been recognized within the Santonian. The intra-Santonian vertical movements were likely caused by the short-term tectonic compression. TST, HST and Lowstand System Ttract (LST) can be allocated within this sequence. The Late Santonian-Maastrichtian sequence has a thickness about 150-250 m. Horizons of former volcanic ashes (bentonite clays) are known from the Campanian deposits: their age coincides with the time of maximum volcanism of the Pontides in the N Turkey. The whole Campanian interval coincides with short LST, TST and HST of 3rd order sequence. The Maastrichtian succession presents an example of a fast regression record, with sediments indicative of a transition from an open shelf to a coastal environment. The HST was followed by LST. The terminal unit of the Maastrichtian indicates a short-term transgression. This transgression and warming may correspond to a global event. At the top of the Maastrichtian a well expressed hard ground is ubiquitous.

This work was supported by the Russian Foundation for Basic Research, projects No. 12-05-00263a and 12-05-00690a.

References

Gale, A.S., Hancock, J.M, Kennedy W.J., 1999. Biostratigraphical and sequence correlation of the Cenomanian successions in Mangyshlak (W. Kazakhstan) and Crimea (Ukraine) with those in southern England. Bull. Inst. Royal Sci. Nat. Belgique. Sci. Terre. 69, Suppl. A, 67-86.

Kopaevich, L.F., 2010. Zonal scheme for the Upper Cretaceous of Crimea-Caucasus area on globotruncanids (planktonic foraminifers). Byull. Moskov. Obst. Ispyt. Prirody, Otdel Geologicheskiy 85(5), 40-52 [In Russian].

Nikishin, A.M., Khotylev, A.O., Bychkov, A.Yu., Kopaevich, L.F., Petrov, E.I., Yapaskurt, V.O., 2013. Cretaceous Volcanic Belts and the Evolution of the Black Sea Basin. Moscow Univ. Geol. Bull. 68(3), 141-154.



20

HIGH AMPLITUDE CRETACEOUS SEA LEVEL FLUCTUATIONS RECORDED IN THE CARBONATE SYSTEMS OF THE EASTERN ARABIAN PLATE

Maurer, F., van Buchem, F.S.P., Dujoncquoy, E. & Rameil, N.

Maersk Oil, Esplanaden 50, 1263 Copenhagen K, Denmark, e-mail: [email protected]

Exceptional outcrop and subsurface datasets available for the Lower and Upper Cretaceous carbonate deposits of the Eastern Arabian Plate allow to document and age date a number of high-amplitude sea- level fluctuations that controlled plate-wide sedimentation patterns. Even though locally tectonic factors have modified the sedimentary expression, the overriding eustatic control is clearly recognisable and can be correlated with similar events on other tectonic plates. The case is made for the need of systematically constructed transects across tectonic plates (margins) in order to improve and create a better hierarchy in the existing global eustatic reference curves.

Our documentation consists of three parts. Firstly, the lower part of the Lower Cretaceous (Upper Berriasian to Late Valanginian) of Oman is represented by a regional 3D seismic survey showing a carbonate platform (Habshan and Salil formations) prograding over a distance of about 150 km. The clinoforms document the variation of sea level fluctuations over the course of this interval with medium-scale sea level fluctuations in the order of 50-100 m in the Berriasian, a maximum sea level fall in the order of 100-150 m in the Early Valanginian, and smaller fluctuations (20-50 m) in the Late Valanginian. Secondly, a plate-wide dataset including seismic, logs, core and outcrops, and detailed biostratigraphy and C isotope stratigraphy, documents the relative sea level fluctuations recorded in the Barremian and Aptian/Early Albian (Kharaib and Shu’aiba Formations). This interval is well known for the occurrence of the Early Aptian global transgression, which in large areas is marked by the accumulation of organic matter, such as in the Bab Basin (Oman, UAE, Iran). In addition, evidence has also been found for a long lasting (5 My) eustatic lowstand that covered most of the Late Aptian. The associated sea level fall is estimated to be in the order of 50 m. Finally, the Cenomanian and Turonian interval (Natih, Mishrif and Sarvak Formations) is characterised by a number of significant sea level fluctuations (20-40 m in amplitude), that find their expression at the scale of the plate.

The construction of similarly complete and well documented transects along the margins of the NeoTethys Ocean would be an important step towards establishing a better insight in the nature (rate and amplitude) of global sea-level fluctuations and their effect on sedimentation patterns.



21

HIGH-RESOLUTION CHEMOSTRATIGRAPHY AND FACIES ANALYSIS OF AN EARLY CRETACEOUS EXPANDED SECTION OF THE ORGANYÀ

BASIN: IMPLICATIONS FOR BARREMIAN-APTIAN GLOBAL δ13C CORRELATION AND SEA LEVEL CHANGES Maurrasse, F.J.-M.R.1 & Sanchez-Hernandez, Y.1,2

1Florida International University, Department of Earth and Environment, 11200 SW 8th Street, Miami, Florida 33199, USA, e-mail: [email protected] 2Fugro, 6100 Hillcroft St Ste 190, Houston, TX 77081, Houston, Texas, USA, e-mail: [email protected]

Here we present a high-resolution δ13Corg profile of the upper 155m of the expanded hemipelagic sequence at El Pui of the semi-restricted Organyà Basin, south central Pyrenees (Sanchez-Hernandez & Maurrasse, 2014). The pattern of the δ13C curve in the El Pui section harmonizes with the global isotopic trend defined by the initial Tethyan model and further provides a higher temporal resolution for global correlation of the carbon isotope curve associated with OAE1a.

The carbon isotope curve shows details of the distinguishing characteristics of segments C2 to C6 (Menegatti et al., 1998), which are widely recognized to be associated with the Early Aptian time interval that comprises OAE1a, as initially reported in the Tethys, and corroborated elsewhere. The detailed δ13Corg profile reveals that segment C2 includes a distinct negative shift of 1.5 ‰, analogous to the sudden negative shift assigned to carbon isotope segment C3, but the latter is more pronounced as it reaches up to ~ 4 ‰. El Pui section provides the distinct pattern of lesser negative episode of C2 so far not well identified in previous works in more condensed sections (Menegatti et al., 1998; Wissler et al., 2002).

Temporal variations of characteristic microfacies, TIC, TOC, and Aluminum normalized redox sensitive trace elements (RSTEs) reveal various degrees of recurring dysoxic to suboxic conditions throughout the interval that concur with enhanced TOC values (>1%). Continuous high accumulation rate is compatible with deepening phase that started in the late Barremian consistent with regional tectonism of a pull-apart basin that developed when Iberia rifted and rotated counterclockwise away from Europe. Despite evidence of recurring oxygen deficient conditions throughout, clear indication of anoxia did not develop in the basin. Facies changes indicative of deepening correlative with eustatic sea level changes occur in the interval corresponding to carbon isotope segment C6 implying diachronous response of the Organyà Basin to the apparent global event during OAE1a. The results of the El Pui sequence underscore the effects of distinctive local feedback related to physiographic factors controlling sediment types, apart from prevailing global forcing mechanisms that caused anoxia elsewhere.

References

Menegatti, A.P., Weissert, H., Brown, R.S., Tyson, R.V., Farrimond, P., Strasser, A., Caron, M., 1998. High-resolution δ13C stratigraphy through the Early Aptian ‘Livello Selli’ of the Alpine Tethys. Paleoceanog.13, 530-545.

Sanchez-Hernandez, Y., Maurrasse, F.J-M.R., 2014. Geochemical characterization and redox signals from the latest Barremian to the earliest Aptian in a restricted marine basin: El Pui section, Organyà Basin, south-central Pyrenees. Chemical Geology 372, 12-31.

Sanchez-Hernandez, Y., Maurrasse, F. J-M.R., Melinte-Dobrinescu, M.C., He, D., Butler, S. K., 2014. Assessing the factors controlling high sedimentation rates from the latest Barremian-earliest Aptian in a restricted marginal basin. Cretaceous Research 51, 1-21.

Wissler, L., Weissert, H., Masse, J.P., Bulot, L., 2002. Chemostratigraphic correlation of Barremian and lower Aptian ammonite zones and magnetic reversals. International Journal of Earth Sciences 91, 272-279.



22

CRETACEOUS SEA-LEVEL CHANGES IN THE SOUTHERN CARPATHIANS (HAŢEG BASIN, ROMANIA)

Melinte-Dobrinescu, M.C. & Briceag, A.

National Institute of Marine Geology and Geo-ecology (GeoEcoMar), 23-25 Dimitrie Onciul Street, RO-024053 Bucharest, Romania, e-mail: [email protected]; [email protected]

The Haţeg Basin formed at the Cretaceous end within the Getic Realm, in response to the Laramian collision of this unit with the Danubian units, following a piggy-back basin evolution during the Late Albian – Late Campanian (Ratschbacher et al., 1993). During the latest Campanian – Early Maastrichtian collapse of the orogen, a strong subsidence took place in the Haţeg area, reflected by the several thousand meter thick terrestrial molasse deposits accumulated in the basin, followed by the Paleogene uplift of the basin and the formation of a positive relief at the collision zone (Willingshofer et al., 2001).

The Mesozoic sedimentary cover is represented by continental Lower Jurassic deposits, followed by marine sequences in the Middle Jurassic - Late Cretaceous (Campanian) interval, interrupted by continental sedimentation during the Albian, and topped by continental deposits in the Maastrichtian. Since the Aptian, following the Mesocretaceous tectonic phase, the region has been uplifted for a short interval. During the exhumation period, which lasted throughout the Albian, the weathering products had been accumulated within the karstic depressions formed on top of the Urgonian limestones, and generated bauxite deposits.

The marine conditions were resumed at the beginning of the Late Cretaceous, and lasted from the Cenomanian to the Late Campanian, with fluctuations between shallow water, outer shelf, and deep water environments, and showing significant differences between the NW and SE regions of the Haţeg Basin (Melinte-Dobrinescu, 2010).

In the NW part, the Cenomanian-Turonian interval is characterized by a pelagic deposition, followed by a turbidite one within the Coniacian-Campanian interval. In SE Haţeg, the sedimentation is mainly characterized by the occurrence of a Lower Cretaceous shallow water carbonate facies, including reef limestones of Urgonian type. During some Late Cretaceous intervals, i.e., the Early Cenomanian and the Late Campanian, gastropods and rudist-bearing limestones, sandstones and microconglomerates have been deposited. Within the Maastrichtian, in the whole region continental deposits with numerous fossils, including dinosaur remains (Grigorescu et al., 1985) occurred.

This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS — UEFISCDI, project number PNII- PCE-2011-3-0162.

References

Grigorescu, D., Hartenberger, J.-L., Rădulescu, C, Samson P., Sudre, J., 1985. Découverte de mammifères et dinosaures dans le Crétacé supérieur de Pui (Roumanie). Compt. Rend. Acad. Sci. Paris 301, 1365-1368.

Melinte-Dobrinescu, M.C., 2010. Lithology and biostratigraphy of Upper Cretaceous marine deposits from the Haţeg region (Romania): Palaeoenvironmental implications. Palaeogeography, Palaeoclimatology, Palaeoecology 293, 283-294.

Ratschbacher, L., Linzer, H.G., Moser, F., Strusievicz, O.R., Bedelean, H., Har, N., Mogos, P.A., 1993. Cretaceous to Miocene thrusting and wrenching along the central South Carpathians due to a corner effect during collision and orocline formation. Tectonics 12, 855-873.

Willingshofer, E., Andriessen, P., Cloething, S., Neubaer, F., 2001. Detrital fission track thermochronology of Upper Cretaceous syn-orogenic sediments in the South Carpathians (Romania): inferences on the tectonic evolution of a collisional hinterland. Basin Research 13, 379-395.



23

EARLY CRETACEOUS CARBONATE PLATFORM EVOLUTION IN THE MANÍN PELAGIC BASIN

(BUTKOV QUARRY, CENTRAL WESTERN CARPATHIANS, SLOVAKIA) Michalík, J.1, Lintnerová, O.2, Soták, J.1 & Boorová, D.3

1Slovak Academy of Sciences, Geological Institute, Dúbravská 9, P.O.Box 106, 84005 Bratislava, [email protected]; 2Comenius University, Faculty of Science, Dept. of Economic Geology, Mlynská dolina G1, 84215 Bratislava, [email protected], 3Dionys Stur State Geological Institute, Mlynská dolina 1,Bratislava, [email protected]

Deposition of Lower Cretaceous hemipelagic planktogenic limestones of the Manin Unit in N part of the Alpine-Carpathian basinal system started after submarine erosion evoked by Late Berriasian extension Michalík and Vašíček, 2013; Michalík et al., 2012). Pelagic limestone formations (the Ladce, Mráznica, Kališčo and Lúčkovská formations filled the Manín basin. Epibenthic colonization of soft bottom was gradual and long-lasting. Benthic epifaunal islands formed around hard objects on muddy bottom in the Kališčo and Lúčkovská formations. The uppermost part of pelagic limestone sequence was dated as Late Barremian due to ammonites of the Vanderheckii Zone (Vašíček, 2010).

Increasing calcification of benthic organisms (and delivery of debris from prograding carbonate slope) resulted in “Urgonian” carbonate platform growth during Early Aptian. Slope sediments start by fillings of submarine channels being followed by cherty organodetrital limestones of the Podhorie Formation. Rocks are characterized by rather high content of micrite; allochems are represented by fragments of heterotrophic organisms, mostly by echinoderms and molluscs. Orbitolinid foraminifers Palorbitolina lenticularis, Orbitolina (Mesorbitolina) parva, Orbitolinopsis simplex indicate Aptian age. The core of platform is formed of massive organodetrital limestones of the Manín Formation. Orbitolinids and fragment of rudist bivalves are more frequent, algal and coral debris occurs subordinately. These facies represented back reef lagoons and/or deeper parts of outer platform. The presence of planktonic foraminifers of Ticinella roberti indicate latest Aptian /Early Albian age of the upper part of the carbonate sequence. Positive and negative excursions of the high resolution δ13C isotope curve could indicate episodes of environmental changes and their effects on bioproductivity in carbonate platform evolution.

The platform growth stopped during mid-Albian collapse when hard rock surface bored by infaunal organisms (boring sponges, bivalves) has formed. Hard ground surface is sometimes covered by stromatolitic growth, ferruginous crusts, glauconite-bearing marlstone or by thin layer of calcisphaerulid limestone. The sequence was covered by thick pelagic shales of the Butkov Fm.

References

Michalík, J., Lintnerová, O., Reháková D., Boorová D., Šimo V., 2012. Early Cretaceous sedimentary evolution of a pelagic basin margin (the Manín Unit, central Western Carpathians, Slovakia). Cretaceous Research 38, 68-79.

Michalík, J., Vašíček, (Eds.), 2013. The Butkov Hill, a stone archive of Slovakian mountains and of the Mesozoic sea life history. Veda Bratislava, pp. 1-164.

Vašíček, Z., 2010. Early Cretaceous ammonites from the Butkov Quarry (Manín Unit, central Western Carpathians, Slovakia). Acta Geol. Polonica 60, 3, 393-415.



24

UPPER CRETACEOUS ROCKS IN THE CEMBERLITAS OILFIELD, (ADIYAMAN) SOUTHEAST TURKEY, NORTHERN ARABIAN PLATFORM:

DEPOSITIONAL ENVIRONMENT AND SEQUENCE STRATIGRAPHY Mulayim, O.1, Mancini, A. E.2, Cemen, I.2 & Yılmaz, O. I.1

1The Middle East Technical University, Department of Geological Engineering Ankara, Turkey; e-mail: [email protected]; [email protected] 2The University of Alabama, Department of Geological Sciences, Tuscaloosa, AL, USA; e-mail: [email protected]; [email protected]

The frontal belt of the southeastern Anatolia fold-thrust zone in Turkey contains several small to mid-size oilfields, producing from carbonate reservoir of the Cretaceous Mardin Group. Many oilfields are related to narrow, asymmetrical anticlinal structures, which are associated with contractional faulting. The Cemberlitas oil field (COF) in Adiyaman, Southeastern Turkey is one of the most important oil fields in the region. The Upper Cretaceous Derdere and Karababa formations of the Mardin Group contain the main reservoir and source rocks in the oil field. We have conducted a detailed study of microfacies, depositional environments and sequence stratigraphy of the Derdere (Mid-Cenomanian-Turonian) and Karababa (Coniacian-Lower Campanian) formations in the oil field. We have recognized 8 microfacies in the Derdere and Karababa formations in the study area; (1) mollusk-echinoid wackestone/packstone, (2) dolomitic planktonic foraminifera wackestone, (3) planktonic foraminifera bearing wackestone/packstone, (4) phosphatic-glauconitic planktonic foraminifera bearing wackestone, (5) lime mudstone, 6) bioclastic wackestone/packstone, (7) medium-coarse crystalline dolostone, and (8) fine crystalline dolostone. These microfacies indicate that the Derdere Formation was deposited in lagoonal to shelf depositional environments and that the Karababa Formation was deposited in a deep to shallow marine intra shelf basin.

We have identified two-third-order sequence boundaries in the reservoir interval. These boundaries are of late Turonian and early Campanian age. Each sequence contains transgressive and highstand systems tracts. Sequence boundaries were recognized by abrupt changes in facies in the stratigraphic succession, such as submarine hardgrounds or subaerial exposures and association of facies representing a shallowing or deepening upward trend in environments. The SB1 contains features suggesting solution enhanced fractures, collapse breccia, vugs and cave floor deposits that developed at the time of subaerial exposure. This surface is recognized as a subaerial unconformity. The SB2 comprises. karstic deposition related to subaerial exposure in marginal areas of the basin. Also, this boundary could be followed by the drowning/sudden subsidence event associated with tectonic movements in the region. These sequences are compared with those in other regions to differentiate the local, regional and global factors that controlled sedimentation within the Cemberlitas oil field area.



25

THE IMPORTANCE OF FRACTURED OLISTOLITHS AND SHELF-GRAVEL SORTING FOR THE CONSTRUCTION OF A TECTONICALLY-CONTROLLED

CARPATHIAN MARGIN, ALBIAN BUCEGI CONGLOMERATES, EASTERN CARPATHIANS, ROMANIA

Olariu, C.1, Jipa, D.C. 2, Steel, R.J. 1, Ungureanu, C.2 & Melinte-Dobrinescu, M.C. 2 1Jackson School of Geosciences, The University of Texas at Austin, USA; e-mail: [email protected] 2National Institute of Marine Geology and Geo-ecology (GeoEcoMar), Romania

The Albian Bucegi Conglomerates are interpreted as a tectonically active Carpathian margin with a narrow shelf to deepwater slope morphology. The spectacular 2,000 m thick conglomerate outcrops of the Bucegi were initially interpreted as large alluvial fans, but later reinterpreted as coarse-grained deepwater slope deposits in an influential article by Stanley & Hall (1978), at a time when studies of modern and ancient deepwater systems were just beginning to take off. We build on the deep water depositional model by interpreting the uppermost third of the Bucegi succession as shelf deposits. Despite the narrowness of this Albian shelf, it was an important staging area. Huge (hundreds of meters) fractured limestone olistoliths were shed from the tips of thrust faults onto the shelf where fractured limestone clasts were further broken up, and where coarse sediment was partially sorted by currents and waves. The shelf interpretation and the shelf processes can be inferred from the sorted grain populations now identified on the deepwater slope (Jipa et al., 2013, Olariu et al., 2014). In the basin margin reconstruction we propose a narrow shelf backed by a thrust system across which a fluvial system with large limestone olistoliths (toward N and NW) that passed basinwards to a shallow marine area toward south and south-east. The rivers and shallow marine processes (waves, possible tides) transferred the coarse material at times directly onto the slope, which was hundreds of meters high (based on the presence of large clinoforms). Deep basinal deposits coeval with the shelf and slope conglomerates have not been described, but the finer Bobu and Teleajen "flysch" deposits that have been interpreted as the same age (Albian) turbidite deposits are potentially genetically linked with the Bucegi conglomerates. The Bucegi shelf was most likely by-passed by sediment during the largest river floods, which delivered the coarsest (conglomerate) and most poorly sorted sediments onto the upper slope. During normal discharges gravel and sand were stored on the shelf, were subject to the significant sorting by waves and shelf currents, and these deposits too were delivered to the slope in periods of flooding. The slope deposits thus show a wide range of poorly to well-sorted, grain populations, including extremely thick (3 to 5 meter beds) inverse graded beds interpreted as highly mobile debris flows. Compared with other basin margins, the Bucegi margin was extremely conglomeratic because of its proximity to the tectonically active mountain range, the huge gravel-rich river discharges and the narrow (10-20 km) shelf.

This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS — UEFISCDI, project number PNII- PCE-2011-3-0162.

References

Jipa, D.C., Ungureanu, C., Ion, G., 2013. Stratigraphy and tectonics of the uppermost Bucegi Conglomerate Formation (Albian, Eastern Carpathians, Romania). Geo-Eco-Marina 19, 1-13.

Olariu, C., Jipa, D.C., Steel, R., Ungureanu, C., Melinte-Dobrinescu, M.C., 2014. Genetic significance of an Albian conglomerate clastic wedge, Eastern Carpathians (Romania). Sedimentary Geology 299, 42-59

Stanley, D.J., Hall, B., 1978. The Bucegi conglomerates: a Romanian Carpathian submarine slope deposit. Nature 276, 60–64.



26

PALYNOLOGY OF THE ALBIAN – CENOMANIAN BOUNDARY INTERVAL IN A PART OF NORTH BULGARIA

Pavlishina, P.

Sofia University ‘St.Kliment Ochridski’, Department of Geology, Palaeontology and Fossil Fuels, ‘’Tzar Osvoboditel’’ Bd. 15, 1504 Sofia, Bulgaria; e-mail: [email protected]

The Albian-Cenomanian boundary interval is palynologically studied in two representative sections, situated in Central and Northwest Bulgaria. The sedimentary successions in these sections have been traditionally assigned to two different facies types – North European and Carpathian. They originated in different depositional environments corresponding to the two types of interrelated Late Cretaceous basins in North Bulgaria (the North European shallow epicontinental basin and the Carpathian type basin).

The Sanadinovo section comprises the most representative Albian-Cenomanian succession of a epicontinental settings. The biostratigraphic framework of this section is based mainly on ammonites with information from foraminifers and calcareous nannofossils (Ivanov et al., 1980; Jolkichev et al., 1988). Recently, the Albian-Cenomanian boundary was evidenced by calcareous nannofossils and dinoflagellate cysts near Tolovitsa karst spring, north of Rabisha mound in NW Bulgaria (Sinnyovsky and Pavlishina, 2014). The continuous grey and green marly sequence in this section is originally referred to the Carpathian type Cretaceous.

Dinoflagellate cysts have a continuous record trough both studied sections. They indicate the Litosphaeridium siphoniphorum Zone. The characteristic zonal association comprises cosmopolitan dinocyst taxa as Litosphaeridium siphoniphorum, Epelidosphaeridia spinosa, Xiphophoridium alatum, Ovoidinium verrucosum and Palaeohystrichofora infusorioides and demonstrates the higher stratigraphical potential of their concurrent range for the latest Albian to early Cenomanian interval.

Palynofacies patterns in the studied sections are also analysed in order to highlight the environments of deposition. High amounts of granular amorphous organic matter (AOM) in the sequence near Tolovitsa karst spring could be considered to indicate the well-documented global latest Albian Oceanic Anoxic Event (OAE 1d). An estimation of surface water nutrient levels is proposed based on a maximum in the dinocyst P/G ratio and the abundance of the peridinioid dinocyst P. infusorioides. This event is recorded in the uppermost Albian sediments of both studied sections, being interpreted as indicative of nutrient rich environments with high primary productivity. The sporomorph spectrum indicates relatively stable vegetation patterns during and after the Albian/Cenomanian boundary interval and suggests warm temperate to subtropical humid climate characteristic to the Southern Laurasian floral province.

References

Ivanov, M., Stoykova, K., Nikolov, T., 1980. Biostratigraphical studies of the Albian Stage in the northern part of Pleven district. An. Uni. Sofia, Geol. 72 (1), pp. 79-87.

Jolkichev, N., Jovcheva, P., Dimitrova, E., Stoyanova-Vergilova, M., 1988. Stratigraphy of the Cenomanian stage north of Pleven and new microfaunistic data on its basement. Rev. Bulg. Geol. Soc. 49, 24-36.

Sinnyovsky, D., Pavlishina, P., 2014. Nannoplankton and palynological evidences for Albian – Cenomanian boundary in North-west Bulgaria. Compt. Rend. Acad. Bulg. Sci., 67, 4, 551-556.



27

DYNAMIC POLAR CLIMATES IN AN EARLY CRETACEOUS GREENHOUSE WORLD

Price, G.D.

School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL4 8AA, UK; e-mail: [email protected]

The Cretaceous greenhouse world witnessed pronounced episodes of palaeoenvironmental change, which were associated with substantial changes in sea level, temperature and the global carbon cycle. Perhaps more controversially, transient cool events have also been suggested. The Cretaceous contains in general sparse and frequently equivocal evidence for glacial conditions and polar-ice. Nevertheless, glacial eustasy has been invoked to explain apparently large and rapid greenhouse sea-level fluctuations. High latitude Early Cretaceous evidence for ice and glacial conditions consists of shales with anomalous pebbles (dropstones) and glendonites (glendonites are calcite pseudomorphs after the metastable mineral ikaite (CaCO3 6H2O). Ikaite typically forms within organic-rich marine sediments that are at near freezing temperatures. Based on such evidence a number of episodes of cold or sub-freezing polar climates during the Valanginian and the Aptian are recognised. Conspicuous by their absence are Late Cretaceous glacial deposits. Isotopic evidence for glacial events has also led to a re-evaluation of Arctic climates during the Cretaceous. Marine temperatures obtained from Early Cretaceous fossil molluscs determined using carbonate clumped isotope thermometry (e.g. Price & Passey, 2013), is consistent with intervals when polar ice was unlikely, but also when polar ice was plausible supporting the view of generally warm but dynamic polar climates. Combined oxygen and clumped isotope data also allow for the assessment of the isotopic composition of seawater.

References

Price, G.D., Passey B.H., 2013. Dynamic polar climates in a greenhouse world: Evidence from clumped isotope thermometry of early Cretaceous belemnites. Geology 41, 923–926.



28

SOURCE TO SINK CONNECTION DURING CRETACEOUS: FROM LATERITIC CRUST TO RELATED SEDIMENTARY DEPOSITS IN DOBROGEA

(SOUTH-EAST ROMANIA) Rădan, S.

National Institute of Marine Geology and Geo-ecology (GeoEcoMar), 23-25 Dimitrie Onciul Street, Bucharest, Romania; e-mail: [email protected]

It is well known that important lateritic weathering episodes are generated during periods of relative tectonic inactivity, on old land areas, under subtropical or warm-humid climate. Interesting lateritic crust relics have been identified in North Dobrogea, scattered all over the western, Măcin zone, were the Precambrian metamorphic rocks and the Paleozoic formations preserve in places signs of a deep weathering. The weathering was produced in close connection with the development of the Early Cretaceous peneplain in Europe. The most complete profile was found close to Mircea Vodă village, formed on gneisses and amphibolites of the Megina Group and preserved under Cenomanian calcareous sandstones (Fig. 1). The crust consists of a saprolite unit, covered by a resedimented sequence of thin sandstones, sands and red clays. In the saprolitic zone, the clay mineralogy is dominated by smectite (up to 100%); kaolinite becomes dominant (70-100%) in the upper levels of the lateritic section and in the resedimented sands and clays; illite is subordinate, while chlorite occurs only accidentally.

Fig. 1

TRANSPORTED COVER

SAPROLITE

SAPROCK

CALCAREOUSSANDSTONESCENOMANIAN

WEATHERING COMPLEX

(REGOLITH)

PARENT ROCK: M E G I N A F O R M A T I O N

6

4

2

0

m

967966

965

964

955

933

K I

S Ch

955

957958

959

960

961

962

963

964

965

966

967

WEATHERING FRONT

K - KaoliniteI - IlliteS - SmectiteCh - Chlorite

Synthetic weathering profile in North

Dobrogea (Ante-Cenomanian)

Synthetic sedimentary columns in South Dobrogea (Aptian)

Continental deposits Marine deposits

The continental fluvio-lacustrine deposits derived from the Ante-Cenomanian weathering crust are represented by Gherghina Formation (Aptian), well developed within the northern half of the South Dobrogea, especially within Medgidia area, and consisting of weakly coherent kaolinitic clays, associated with subordinate sands, gravels and coaly clays, or even thin coal beds (Fig. 1). This formation is interfingering with a marine epicontinental sequence (Ramadan Formation) represented by limestones, marls, clays and sands. The clay mineralogy is dominated by kaolinite within the continental deposits, excepting coaly clays (rich in smectite), and by smectite within the marine clays and marls (Fig. 1). The continental sands and gravels reveal transport directions from north, north-east and possibly east.



29

MID CRETACEOUS SHORT-TERM ORBITAL CYCLES: THE EASTERN CARPATHIAN CASE STUDY

Roban, R-D.1,2, Melinte-Dobrinescu, M.C.3, Mitrică, D.4, Mihai, A.1 & Krézsek, C.5

1University of Bucharest, Faculty of Geology and Geophysics, 1 Nicolae Bălcescu Bld, RO- 010041, Bucharest, Romania, email: [email protected] 2National Institute of Marine Geology and Geo-ecology (GeoEcoMar), Romania, 23-25 Dimitrie Onciul Street, RO-024053 Bucharest, Romania, e-mail: [email protected] 3Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, Netherlands

4OMV Petrom, 22 Coralilor Street, Bucharest, Romania

The Late Albian-Early Turonian interval is mainly made, in the outer Eastern Carpathians, by green radiolarian chert/grey to black siliceous shales couplets and clastic radiolarites, characterizing the upper part of the Tisaru Formation; the benthic foraminiferal assemblages indicate a depth of around 2,500 m (Bădescu, 2005). The Tisaru Formation follows the Streiu Formation, Barremian-Albian in age, mainly composed of grey and black shales and is overlain by the red shales/wackestones couplets and the red shales/grey-greenish marlstone couplets of the Tisaru Formation Upper Member. The base of the Tisaru Formation is latest Albian, being placed in the CC9 nannofossil zone, while the boundary between the Lower Member and the Upper Member of this unit is situated in the Early Turonian, slightly above the first occurrence of the nannofossil Quadrum gartneri that marks the base of the CC11 zone. In the whole Late Albian-Early Turonian interval, the nannofossil assemblages yielded a poor diversity and abundance, but their continuous presence indicates a sedimentation above the CCD. The bioclasts and carbonate pellets found in the radiolarian chert/shale couplets indicate a similar deep-marine palaeoenvironment. High TOC values, between 1.2% and 3%, have been found in the black shales and around 0.1% in the grey shales and radiolarites. The compacted thickness of a radiolarite/shale couplets averages 6 cm, while the uncompacted thickness has been 20 cm (Vârban, 2003). For the decompacted model, a 2x factor has been used for shales and 5x for the radiolarites (Tada, 1991). Considering the global sedimentation rates of those times, i.e., 10-33 m/1 My for decompacted sediments (De Wever & Baudin, 1996), we may assume that the radiolarite/shale couplets of the Lower Member of the Tisaru Formation correspond to the precessional Milankovitch cycles. It is to suppose that, during cooler episodes, characterized by an estuarine circulation and intensification of the upwelling nutrient-rich currents, the radiolarites accumulated, while, in the warmer intervals the clayey sedimentation prevailed. As in the decompacted couplets the radiolarites dominated over the clays, we may assume that a high bioproductivity prevailed in the Eastern Carpathian outer part, during the Late Albian-Early Turonian interval. Probably, the cooler/warmer climatic modes alternated in short intervals, of 10,000-20,000 y. A change took place in the Early Turonian, when the red shales started to be accumulated, linked to a significant terrigenous influx. This probably corresponds to the event KTu2 of Haq (2014).

This work was supported by a grant CNCS - UEFISCDI, Project number PNII- PCE-2011-3-0162.

References

Bădescu, D., 2005. Evoluţia tectono-stratigrafică a Carpaţilor Orientali în decursul Mesozoicului şi Neozoicului. Editura Economică Bucureşti, 308 pp.

Haq, B. U., 2014. Cretaceous eustasy revisited. Global and Planetary Change 113, 44-58. Tada R., 1991. Compaction and cementation in siliceous rocks and their possible effect on bedding

enhancement. In: Einsele, G., Ricken, W. & Seilacher, A. (Eds.), Cycles and events in stratigraphy, Springer-Verlag, p. 480-491.

Vârban, B.L., 2003. Analiza sedimentologică a secvenţelor ciclice de vârstă Cretacic superior din Moldavide: reconstituiri paleoambientale. Unpublished Ph.D. Thesis, Univ. Bucharest.

De Wever, P., Baudin, F., 1996. Paleogeography of radiolarite and organic-rich deposits in Mesozoic Tethys. Geol. Rundsch. 85, 310–326.



30

CRETACEOUS EUSTASY: INDUSTRIAL PERSPECTIVES Simmons, M.D.

Neftex, 97 Jubilee Avenue, Milton Park, Oxford, OX14 4RW; e-mail: [email protected]

Although the roots of an understanding of eustasy are much older, it was the work of Peter Vail, Bilal Haq and others that opened the eyes of the oil and gas industry to the potential predictive power that an understanding of eustasy engenders (Simmons, 2012). Since that time, industrial geoscientists have pondered both the validity of eustatic models, their potential driving mechanisms and, most importantly, if such models can help find and produce significant oil and gas accumulations more efficiently.

Of course, it is oil industry geoscientists who have access to much of the data to confirm or deny eustatic models – biostratigraphically constrained well sections and seismic data from around the globe, plus reference to published outcrop studies. This data has been used at regional (e.g. Sharland et al., 2001) and global scale (e.g. Simmons et al, 2007) to demonstrate that eustasy can indeed be validated and the driving mechanisms for its occurrence explored. The evidence for climatically driven oscillations in sea-level is growing, related to glacio-eustasy, even in “greenhouse” times such as the Cretaceous (Miller, 2009).

From an industrial perspective, the real value of a eustatic model is that is provides a precise temporal framework for the correlation, prediction and mapping of facies - facies that can be related understanding the risk on the presence of source rocks, reservoir rocks and seals – 3 key elements in defining exploration targets. At its heart, the basic premise of exploration geoscience is really very simple – make maps showing the potential distribution of reservoirs, source rocks and seals. These need to be drawn as accurate and precisely as possible, filling in the “white space” where no data exists. An understanding of eustasy makes this possible.

An assessment of analogues and generic play concepts is also made possible. For example, where else on the planet will the late Turonian lowstand play discovered in Ghana be possible? This in turn links eustasy to geodynamics and ultimately to palaeoclimate models predicting upwelling, precipitation, etc. It helps explorationists break out of confusing lithostratigraphy and use a series of time-signifi-cant surfaces to combine wireline logs with seismic data with sedimentological observations, etc.

In this presentation I will explore some of the latest industrial thinking on Cretaceous eustasy and show how it has been utilised in the quest to find more oil and gas with examples from a global perspective.

References

Miller, K.G., 2009. Palaeoceanography: Broken greenhouse windows. Nature Geoscience, 2, 465-466. Sharland, P.R., Archer, R., Casey, D.M., Davies, R.B., Hall, S.H., Heward, A.P., Horbury, A.D. & Simmons,

M.D.., 2001. Arabian Plate Sequence Stratigraphy, GeoArabia Special Publication 2, 371 pp. Simmons, M.D., 2012. Sequence Stratigraphy and Sea-Level Change. In: Gradstein, F.M., Ogg, J.E., Schmitz,

M.D.. & Ogg, G.M. (Eds.), The Geologic Time Scale 2012. Elsevier, pp. 239-267. Simmons, M.D., Sharland, P.R., Casey, D.M., Davies, R.B. & Sutcliffe, O.E., 2007. Arabian Plate sequence

stratigraphy: Potential implications for global chronostratigraphy. GeoArabia, 12, 101-130.



31

ASTRONOMICAL TUNING OF THE UPPER ALBIAN – LOWER CAMPANIAN: FROM SHORT TO VERY LONG-TERM ORBITAL CYCLES

Sprovieri, M.

Istituto per l’Ambiente Marino Costiero, Consiglio Nazionale delle Ricerche (IAMC-CNR), Capo Granitola, Campobello di Mazara (Tp), Italy; e-mail: [email protected]

A new astronomical tuning of the upper Albian−lower Campanian Bottaccione sedimentary record (Gubbio, central Italy) is here proposed and based on long-term δ13C eccentricity cycles tuned to the highly stable 405 kyr cycles of the La2010 astronomical solution. The achieved orbital tuning provides a refined age model for dating biostratigraphic, magnetostratigraphic and carbon isotope events reported through the studied record. Also, ~8.0, 4.7, 3.4 and ~2.4 Myr cycles modulate the entire δ13C record and offer the opportunity to extend their detection from the Cenozoic to ~100 Ma; these represent primary and stable long-term oscillation modes of Earth’s climate-ocean system. We speculate that the periodicity at 4.7 Myr, represents a homologue of the present eccentricity grand-cycles, evolved by the chaotic behaviour of solar system planets during the Mesozoic. This very long-term eccentricity control, modulated by periodic low-energy cycles, is suggested to play a crucial role in carbon cycling, controlling a chain of climate sensitive global biogeochemical processes on the Earth. These grand-cycles could provide robust tool for geological correlation and reliable constraint for accurate calculation of the orbital evolution of the Solar System.



32

IMPORTANCE OF TIDAL DEPOSITS IN THE CAMPANIAN WESTERN INTERIOR SEAWAY, USA

Steel, R.J.

Jackson School, University of Texas at Austin, Austin, Tx 78712; e-mail: [email protected]

The effects of tidal waves entering the Cretaceous Western Interior Seaway from the Gulf of Mexico have previously been modeled, but the field evidence for tides in the Campanian succession has never been assembled. Tidal deposits in deltaic, estuarine and barrier-lagoon successions along the southwestern margin of the seaway, USA are documented. Tidal currents dominated the distal, subaqueous segments of many regressive deltaic transects (setting 1), and tidal influence was strong during the transgressive backstepping (setting 2) of shorelines. Marked tidal influence in setting 2 was likely due to increased tidal constriction and coastline irregularity after valley incision as well as possible tidal resonance with the increase of shelf width accompanying sea-level rise. In the regressive deltaic setting the common basinward cross-shelf trend from wave- to tide-dominated probably resulted from tidal amplification as sea level fell (albeit few tens of meters). The seaway narrowed and possibly became restricted to the north during lowstand periods, enhancing the counter-clockwise, Coriolis-driven current gyre in the southern half of the basin. In addition, there is notable increase in tidal influence along all of the 77.5-75Ma shorelines, irrespective of sea-level stand. These more embayed shorelines (contrasting with straight wave shorelines before and after) are likely due to irregular widespread shallowing around embryonic, subaqueous basement-involved topography, as the seascape adjusted to a slight basinward tilt (as opposed to the earlier backtilt of the foreland basin) and a much more irregular, shallow bathymetry during the Sevier-Laramide transition.



33

PALYNOLOGY AND GENETIC SEQUENCE STRATIGRAPHY OF THE RESERVOIR ROCKS (CENOMANIAN, BAHARIYA FORMATION) IN THE

SALAM OIL FIELD, NORTH WESTERN DESERT, EGYPT

Tahoun, S.S.1 & Mohamed, O.2

1Cairo University, Faculty of Science, Geology Department, 12613 Giza, Egypt 2Minia University, Faculty of Sciences, Geology Department, El-Minia, Egypt; e-mail: [email protected]

Twenty-eight samples from the Bahariya Formation of the Salam-17 Well in the north Western Desert were palynologically investigated. These samples are of Cenomanian age. Fair diversity and fair to moderately preserved palynomorph assemblage has been recovered. Among them, the dinoflagellate cysts showed very poor diversity and abundance. Four miospore zones have been informally identified in the lower Cenomanian. Various palynofacies criteria, adopted from previous publications (e.g. relative particle abundance data, brown to black wood ratio, equi-dimensional to lath-shaped black wood ratio, average size of phytoclasts and spores/pollen ratio) are applied as alternative indicators to monitor the proximaledistal trends instead of the marine palynomorphs-based parameters. The method can be applied in the Egyptian Western Desert to overcome the rarity and absence of dinoflagellate cysts in the recovered organic residues. The palynofacies study of the section demonstrates a predominantly regressive phase, characterized by deltaic, distributary or tidal channels, interrupted by short-lived marine incursions. The palynofacies trends within the studied succession indicate six genetic sequences informally described as Genetic Stratigraphic Sequences A through F.



34

A CLIMATIC/BIO EVENT IN THE CRETACEOUS PALAEOGENE BOUNDARY, KOCAELİ PENINSULA, NW TURKEY

Tüysüz, O.1, Yılmaz, I.O.2, Genç Ş. C.3, Özcan, E.3, Egger, H.4 & Gallemí Paulet, J.5 1Istanbul Technical University, Eurasia Institute of Earth Sciences and Faculty of Mines, 34469, Maslak, Istanbul, Turkey; e-mail: [email protected] 2Middle East Technical University, Faculty of Engineering, Department of Geological Engineering, 06531, Ankara, Turkey; e-mail: [email protected] 3Istanbul Technical University, Faculty of Mines, 34469, Maslak, Istanbul, Turkey, e-mail: [email protected]; [email protected] 4Geological Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria; e-mail: [email protected] 5Museu de Geologia de Barcelona-MCNB, Parc de la Ciutadella s/n, 08003 Barcelona, Spain; e-mail: [email protected]

Bithynian (Kocaeli) Peninsula, NW Turkey, is located to the east of Bosphorus, on the Istanbul Zone, one of the main tectonic units of Northern Turkey. Cretaceous to Eocene sediments, covering a large area on the Kocaeli Peninsula, are represented by a thick sequence. At the base of this unit there are red beds deposited in alluvial fan and braided river environments. This continental unit grades upwards into rudist-bearing shallow marine carbonates, being followed by pelagic carbonates and calciturbidites. Towards the north, some volcanic intercalations, such as tuffs and agglomerates, are also present. Requinids, ammonoids, inoceramids, echinoids, ammonites, benthic foraminifera and nannofossil data indicate that this unit is Late Campanian to Maastrichtian in age.

It was concluded in many previous studies that this thick Upper Cretaceous unit grades transitionally upwards into Palaeogene sediments. In contrast to previous interpretations, our measured sections and fossil determinations indicate that a regional unconformity separates the upper Maastrichtian and lower Palaeocene carbonate/mudstone/marl units. Below this unconformity is a kill zone, which is represented by zone of flood abundance of echinoid fossils and calcispheres. This indicates that the regional unconformity is also associated with a climatic and/or bio-event as well, not only with tectonics.



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CENOMANIAN-TURONIAN PALAEOGEOGRAPHY OF THE PONTIDES, NORTHERN TURKEY

Tüysüz, O.1, Melinte-Dobrinescu, M.C.2 & Yılmaz, I.O.3

1Istanbul Technical University, Eurasia Institute of Earth Sciences and Faculty of Mines, 34469, Maslak, Istanbul, Turkey; e-mail: [email protected] 2National Institute of Marine Geology and Geo-ecology, Department of Stratigraphy and Palaeontology, 23-25 Dimitrie Onciul Street, RO-024053 Romania; e-mail: [email protected] 3Middle East Technical University, Faculty of Engineering, Department of Geological Engineering, 06531, Ankara, Turkey; e-mail: [email protected]

The Pontides that form the southern continental margin of the present Black Sea consist of two tectonic units: (i) the Istanbul Zone in the west, and (ii) the Sakarya Zone in the east. Different tectonic models had been proposed for the timing and mechanism of the juxtaposition of these units.

Lithostratigraphic units older than Cenomanian deposited on both tectonic units and show differences; the Turonian lithostratigraphic units and the younger ones form a common cover of both tectonic units. Understanding palaeogeographic conditions of the Pontides during the Cenomanian-Turonian interval can shed light onto the problem how and when these two different tectonic units juxtaposed.

The Cenomanian on the Istanbul Zone was a time of fast uplifting and erosion. Sedimentary basins, which started to open during the Late Barremian, deepened until the beginning of the Cenomanian, then regionally uplifted and eroded. The sediments of this regional unconformity are represented by conglomerates at the base and an overlying suddenly deepening sequence associated with an intense magmatism developed in response to northward subduction of Tethys Ocean to the south of the Pontides. The oldest dating from this sequence comes from pelagic sediments alternating with volcanics and volcanoclastics and indicates a Middle Turonian age.

In contrast to the Istanbul Zone, the Cenomanian and Turonian sediments of the Sakarya Zone are represented by distal turbidites, shales and radiolarian cherts. Alternating red and black shales have been deposited within the Cenomanian/Turonian boundary interval; this age is argued by calcareous nannofossil and radiolarian assemblages.

Based on sedimentological, geochemical and palaeontological data, it has been concluded that deposition of these sediments was commonly controlled by the sudden rise of the sea level during the Late Cenomanian, associating climate induced small-scale sea level changes, palaeoproductivity and tectonics. The character of the Cenomanian-Turonian boundary interval successions displays similarities with successions of the same age from various European areas.

In this work, the stratigraphy and palaeogeography of the Pontides during the Cenomanian and Turonian stages are described; the palaeoclimatic and tectonic conditions of this interval are also discussed.



36

BASIN SUBSIDENCE AND ITS IMPLICATION TO SEDIMENTARY SEQUENCE GENERATION, CENTRAL ROMANIAN BLACK SEA OFFSHORE

Ţambrea, D.1, Dinu, C.2 & Munteanu, I.3

1Danubian Energy Consulting SRL, 42-44 Vasile Lascar St., 5th Floor, 11th Suite, Bucharest, Romania, e-mail: [email protected] 2University of Bucharest, Faculty of Geology and Geophysics, 6 Traian Vuia St., Bucharest, Romania; e-mail: [email protected] 3Repsol, Exploration Europa del Este, Calle Méndez Álvaro No. 44, 28045, Madrid, Spain

The crustal structure of the Romanian Black Sea Offshore is made up by two main units, well studied in the outcrops onshore: the North Dobrogea Folded Belt (NDO) and the Moesian Platform, separated by the Peceneaga-Camena Fault. The Moesian Platform itself is sub-divided by the Capidava-Ovidiu Fault in Central Dobrogea (an uplifted block displaying platform basement) and South Dobrogea. Onshore the NDO structures are overlain in the southern part by the Upper Albian to Campanian sediments of the Babadag Basin, with an opened like half-graben geometry bordered by the Babadag Fault to the North. Its offshore prolongation is represented by the Histria Depression border upon Heracleea Fault to the North and Pecenega-Camena Fault to the South, filled with Cretaceous - Paleogene deposits, which represent the area for the current study.

The petroleum exploration has developed numerous tools for the study of the structural, thermal and sedimentological evolution of the sedimentary basins. One of these relatively old but powerful tools is the study of subsidence patterns, which in correlation with others proves useful in the understanding of the tectonic and stratigraphic evolution of basin fill.

Our calculation of the tectonic subsidence follows Allen & Allen (1990). Lithological and stratigraphic data are obtained from various sources including published information. Choices of heat flow and thermal parameters have been guided by Veliciu (2002). The layer thickness results from the stratigraphic dates determined on samples and cores from wells. Decompaction parameters resulted using the exponential decompaction curves of the forms ф = ф0 exp (-cz), where ф is porosity, ф0 is initial porosity, and c is a scale factor of loses of porosity with depth, z (values resulted from analyzing all the geological and geophysical data from wells). The values of the palaeowater depth used for calculation of the tectonic subsidence based on the sedimentary structures, facies analyses and fossils assemblages.

Tectonic processes that control the stratigraphy and the geometry of the Histria Depression include mainly the extensional and ‘compressional’ movements creating and modifying the space accommodation (Dinu et al., 2005). The sediment supply into the basin is other parameter that affects the evolution of the sub-basins, erosion of the proximally uplifted areas and transport into basins increases the sediment load within basin resulting in increase of thicknesses and compaction.

A third variable that significantly controls the stratigraphy is the eustatic sea level falls and raises that cause progradation and retreat of the facies boundary. Any change of these factors resulted in creation or destruction of the accommodation space and formed discordances, which are expressed by toplap, downlap and erosion of beds delimiting the sedimentary sequences.

Generally all the subsidence curves show more distinct subsidence pulses related with the tectonic evolution of the Histria Basin. The evolution of this basin has began in the Albian; the deposition of syn-rift sediments has been controlled by the NW-SE normal faults paralleling of the North Dobrogea Orogen and characterized by a maximum subsidence in the Portita area. During this time, the main active tectonic element seems to be Lebada Fault. The depocenter of maximum subsidence migrated southward towards the Poseidon area during the Cenomanian, influenced by the strike-slip motion, Lebada Fault and Lotus-Venus Fault being the main active faults.



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In the Senonian, it seems that the strike-slip movement produced a narrow rectangular graben with two subsidence depocenters: one situated in the western part of Poseidon area and the second located north from Callypso area. The Paleocene stratigraphic gap established by the wells drilled in the study area was confirmed by the subsidence analysis showing a quiet from a tectonic point of view. The Eocene maintains the trend evolution from the Senonian, being characterized also by two subsidence depocentres: Venus area and Minerva area, producing two sub-basins (Venus-Lotus and East Lebada).

Nowadays, the Cretaceous-Paleogene structures/sediments are deep buried beneath the Upper Paleogene-Quaternary sediments, with an overall E-ward sequence progradation and coeval thickness increase. The subsidence pattern display the complex tectonic-sedimentary evolution of the basin during this time, as a combined effect between thermo-tectonic and sediment compaction subsidence. The analysis of the subsidence patterns shows that deposition of the Cretaceous sediments of the Histria Depression is driven by the thermo-mechanical tectonic subsidence processes.

References

Allen, A.A., Allen J.R.., 1990. Basin Analysis: Principles and Applications. Blackwell Publ. Ltd., Oxford, 451 pp. Dinu, C., Wong, H. K., Ţambrea, D., Maţenco, L., 2005. Stratigraphic and structural characteristics of the

Romanian Black Sea shelf. Tectonophysics 410, 417-435. Veliciu, S., 2002. Heat flow of the North-Western Black Sea Region. In: Dinu, C. and Mocanu, V. (Eds.).

Geology and Tectonics of the Romanian Black Sea Shelf and its Hydrocarbon Potential. B.G.F. Special Volume 2, 53-58.



38

LIMNO-EUSTASY – A MECHANISM FOR SHORT-TERM EUSTATIC SEA-LEVEL CHANGES DURING THE CRETACEOUS GREENHOUSE CLIMATE

Wagreich, M., Sames, B. & Lein, R.

University of Vienna, Department for Geodynamics and Sedimentology, A-1090-Vienna, Austria. E-mails: [email protected]; [email protected]; [email protected]

The term "eustatic movements" was introduced by the Austrian geologist Eduard Suess in the year 1888 referring to the phenomenon of displaced shorelines and the worldwide synchroneity of marine events. Eustasy now describes global sea-level changes that play a major role in controlling marine sedimentary sequences and sequence stratigraphy.

Relative (regional and local) and global (eustatic) sea-level fluctuations are controlled by a variety of processes. Mantle convection and resulting gravity anomalies, tectonic movements creating subsidence and uplift, and climate are the main drivers, and apply for different temporal and spatial scales. The long-term sea-level record, i.e. 1st to 2nd order cycles and stratigraphic sequences, occurring over millions to tens of millions of years, is mainly controlled by the internal dynamic history of the Earth, e.g., the changing rates of ocean crust production. Short-term eustatic sea-level changes during ice house phases of Earth’s climate are clearly controlled by waxing and waning of continental ice sheets. However, significant short-term, i.e. 10s kyr to a few myr (3rd to 4th order cycles), sea-level changes during greenhouse episodes of Earth history are still enigmatic. Such cycles are often explained by the presence of ephemeral ice sheets even during the hottest greenhouse phases of the Phanerozoic climate history such as the mid-Cretaceous. However, the possible effect of groundwater storage and release on sea-level change, as particularly important during ice-free greenhouse-phases, has been widely underestimated in its order of magnitude. It is considered to constitute a water volume that is about equivalent to today’s ice volume, thus corresponding to a potential sea-level change of up to ca. 50 m applying isostatic adjustment. Groundwater storage, including both freshwater and saline pore waters, exceeds lake and river storage capacities by several orders of magnitude. Changes in continental groundwater storage may have had a profound effect on sea-level fluctuations and cycles during major greenhouse phases of Earth history.

We introduce the term “limno-eustatic” (Wagreich et al., 2014) to describe the effect of water volumes that are bound to groundwater and lake storage on sea-level fluctuations and cycles during major greenhouse phases of Earth history. Based on these terms the dimension of purely ice-driven glacio-eustatic processes can be better differentiated.

The limno-eustatic hypothesis may be testable given high-resolution stratigraphic correlations between marine and continental lake archives during supposed ice-free periods of Earth history. Lake-level and sea-level fluctuations should be in an out of phase relation, i.e., a major marine sea-level lowstand should correspond to a lake-level highstand, and vice versa. Preliminary tests using selected stratigraphic levels of the Late Cretaceous record of the long-lived lacustrine Songliao basin in China indicate such an out-of-phase relation, and thus support the limno-eustatic hypothesis as a mechanism to explain significant short-term sea-level fluctuations during greenhouse climate phases.

We acknowledge funding by the Austrian Science Fund Project P24044-N24, and UNESCO IGCP 609.

References

Wagreich, M., Lein, R. & Sames, B., 2014. Eustasy, its controlling factors, and the limno-eustatic hypothesis – concepts inspired by Eduard Suess. Austrian Journal of Earth Sciences, 107(1).



39

EARTHTIME CHINA: INTEGRATED CRETACEOUS STRATIGRAPHIC TIME SCALE OF CHINA

Wan, X.,Wu, H. & Xi, D.

China University of Geosciences, Beijing 100083, China, e-mail: [email protected]

In the International Chronostratigraphic Chart (ICC) from 2013, 10 GSSPs (Golden Spikes) that have been defined in China, become major indications for global stratotype. Time (geological age) is the basic element in stratigraphic division and correlation. The precision is upgrading in certain areas and geological periods upon the Earthtime Project. Whether biostratigraphy or isotope stratigraphy, the precision cannot be completely increased by single method.

The Earthtime-China plays more attention to an integrated research, including isotopic chronostrati-graphy, biostratigraphy, magnetostratigraphy and cyclostratigraphy among others, to set up a stratigraphic time scale of China. Cretaceous is a case study of Earthtime-CN. In China, the marine deposits are described in the Tibetan Tethys, Kashi-Hotan Region of Xinjiang, and eastern Heilongjiang. The sedimentary facies and paleogeography are diversified.

In Tibet, the basin evolution is largely related to the subduction and collision of the Indian Plate against the Eurasian Continent, and shows a tectonic evolution in the Cretaceous. Foraminifera and radiolaria are dominant biota in the Tibetan Tethys. Their zones mark the Late Cretaceous chrono-biostratigraphy. Nonmarine sediments include variegated clastic and volcanic rocks, and contain diverse and abundant terrestrial faunas and floras, as well as important coal and oil resources. NE China is the type area of nonmarine Cretaceous.

The Lower Cretaceous strata are well studied in the north Hebei and west Liaoning area, and the Upper Cretaceous completely occurs in the Songliao area. The Songliao Basin is the largest Cretaceous oil and gas-producing lacustrine basin in China, with its greatest aerial extent in the middle Cretaceous. The sequence consists mainly of lacustrine sandstone, dark grey mudstone, shale and oil-shale. Late Cretaceous microfossils are diverse and abundant. A detailed biostratigraphic study has subdivided the sequence into high precision biozones: 21 ostracode assemblages, 10 phytoplankton assemblages, 7 palynological zones and 4 charophyta assemblages, respectively. Some layers of marine foraminifera have been also discovered from the basin. Three 206Pb/238U ages and one 40Ar/39Ar age were analyzed. Ten local magnetozones have been recognized. The ratios of the cycle periods in these stratigraphic units are ~20:5:2:1, 38.4 kyr obliquity and 20 kyr precession cycles. An astronomical time scale is established, which provides precise numerical ages for stratigraphic boundaries, biozones, geoevents. It is likely that the K/Pg boundary is within the member 2 of the Mingshui Formation by new micropaleontologic and magnetostratigraphic data. The integrated study on the biostratigraphy, magnetostratigraphy, chronostratigraphy and cyclostratigra-phy can correlate with Upper Cretaceous stages in the ICC.

Based on the occurrence of nonmarine strata in N China, Cretaceous nonmarine chronostratigraphy can be subdivided in ascending order as the Jibeian, Reholian and Liaoxian stages of Lower Cretaceous; and the Nonganian, Songhuajiangian and Suihuanian stages of Upper Cretaceous. The bottom age of each stage is assigned as 145 Ma, 130Ma, 119 Ma, 100.5 Ma, 86.1 Ma and 79.1, Ma respectively.



40

CHALLENGES IN RECONSTRUCTION AND GLOBAL CORRELATION OF CRETACEOUS SEA-LEVEL FLUCTUATIONS

Wendler, I.

Department of Geological Sciences, University of Bremen, P.O. Box 330 440, D-28334 Bremen, Germany, e-mail: [email protected]

Resolving questions on the amplitude, timing and ultimate causes of sea-level change during the Cretaceous greenhouse world requires high precision in correlating sections on a global scale and an understanding of the proxies used for reconstructing sea-level shifts. In addition to the traditionally used biostratigraphy, the increased availability of chemo- and magnetostratigraphic data during the past years now enables comparison of sections that are dated with different biostratigraphic schemes and allows to correlate them with higher resolution than with biostratigraphy alone. However, these techniques also make us increasingly aware of a number of problems that involve inconsistencies in taxonomic concepts, rare occurrence or selective preservation of key taxa or their true diachroneity in the sedimentary record. The discovery of exquisitely preserved Late Cretaceous sediments from Tanzania not only offers a chance for studying the geochemistry of minimally altered Cretaceous microfossils but also opens a window into the rich world of structural details that are typically not preserved in Cretaceous microfossils. The added amount of detail in many cases calls into question existing taxonomic concepts and sometimes requires profound taxonomic revisions that often have considerable importance for biostratigraphy. A study of a Turonian drill Site from Tanzania further indicates that benthic foraminifera and other proxies that are used for reconstructing past sea-level give conflicting results, pointing to the need to revise some of the traditionally used concepts of proxy interpretation for sea-level reconstruction in the Cretaceous.



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SEA LEVEL – EVALUATING THE PULSE OF THE EARTH SYSTEM Wendler, J.E.

Department of Geosciences, Bremen University, P.O. Box 330440, 28334 Bremen, Germany, e-mail: [email protected]

One representation of the pulsating Earth system is the fluctuating sea level. This pulse has been shown to have cyclic global as well as seemingly non-cyclic components. Alternations in sea level are prevalent regardless of the climate modes of the system – greenhouse and icehouse. Sea level variability controlled by ice is characterized by high frequency and high amplitude changes. The high amplitudes of sea level changes seem to disappear during greenhouse climate modes while the underlying low amplitude beats remain throughout the entire Milankovitch frequency spectrum. It is interesting to evaluate the origins of this persistent pulse: Obviously, water has to be stored outside the oceans in order to lower eustatic sea level – has it always been stored solely in ice? What is the balance of evaporation and precipitation between sea level highs and lows? In the present talk an astrochronologically constrained sequence stratigraphic framework from the Turonian Levant Carbonate Platform, Jordan is shown. Its sea level fluctuations are correlated to equatorial weathering changes suggestive of a causal link between peaks in tropical precipitation amounts and sea level lowstand. A more intense hydrological cycle during sea level lows will have transported water to the poles where it can be bound in ice provided low enough polar temperatures. Hothouse climate GCM suggest, however, that increased atmospheric water content raises latent heat transport to the poles and thus may potentially inhibit polar temperature to fall below freezing. This controversy implies that the ice storage might not have worked during greenhouse epochs. Hence fluctuations in alternative water reservoirs, aquifers in particular, are likely to have forced sea level changes during those epochs of the Earth system.



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SEQUENCE STRATIGRAPHIC CORRELATIONS BETWEEN SEDIMENTARY BASINS IN EUROPE, NORTHERN AFRICA AND THE MIDDLE EAST:

IMPLICATIONS FOR AMPLITUDES, RATES AND PERIODICITIES OF EARLY LATE CRETACEOUS SEA-LEVEL CHANGES

Wilmsen, M., Janetschke, N. & Niebuhr, B.

Senckenberg Naturhistorische Sammlungen Dresden, Museum für Mineralogie und Geologie, Sektion Paläozoologie, Königsbrücker Landstr. 159, D–01109 Dresden, Germany; [email protected], [email protected], [email protected]

The mid-Cretaceous epoch (ca. 80–120 Ma) with its climatic hothouse, long-term sea-level rise and highstand, oceanic anoxic events and associated biotic crises provides a biohistoric case study of exceptional importance for the ongoing discussions of present and future Global Change. A very interesting and yet only poorly understood issue in this context are the large and obviously fairly rapid early Late Cretaceous (Cenomanian–Turonian, C–T ~100–90 Ma) sea-level changes that punctuated this Phanerozoic highstand interval. In order to test the isochrony of those early Late Cretaceous sea-level changes, a sequence stratigraphic study of selected Cenomanian–Turonian basins on different tectonic plates (Europe, northern Africa, Middle East) has been conducted. Numerous sections of well exposed shelf successions have stratigraphically been calibrated and correlated by means of integrated approaches, especially high-resolution ammonoid biostratigraphy, carbon stable isotopes and cyclostratigraphy. In combination with analyses of (bio-)facies and stratal architectures (such as on-/offlap geometries or incision at sequence boundaries), a precise correlation of unconformities and an assessment of the amplitudes of sea-level changes involved in their formation has been possible. High-resolution orbital time-scales provide the possibilities to elucidate the rates of sea-level change.

The sequence stratigraphic case studies have been conducted in several basins in the periphery of the Mid-European Island (Münsterland, Saxonian and Danubian Cretaceous basins), in the Eastern Desert of Egypt and in Iran (Koppeh Dagh and Central Iran). The study shows that C–T sea-level changes have in fact been strictly time-equivalent and iso-directional, i.e. eustatic, on different tectonic plates. Major sea-level falls, resulting in the development of depositional sequence bounding (i.e., 3rd-order) unconformities, occurred during the latest Albian (SB Al 11), the early, mid- and latest Early Cenomanian (SB Ce 1–3), the late Middle and mid-Late Cenomanian (SB Ce 4 and 5), the Lower–Middle Turonian boundary interval (SB Tu 1), the Middle Turonian (SB Tu 2) as well as the early, mid-and late Late Turonian (SB Tu 3–5) in all investigated basins.

The quantification of sea-level changes involved in the formation of selected sequence boundaries indicate large-scale variations of up to 50 m within time spans of a hundred thousand years and less. The resulting high rates suggest glacio-eustasy (or a yet unknown process) as their driving force. All other so far known geological processes are either too long-term or of too low-amplitude. Therefore, our study provides independent stratigraphic evidence for short-term build-up and decay of significant quantities of continental ice in Antarctica and/or high altitudes during “cold snaps” in a generally very warm Cretaceous super-greenhouse world, supporting recently published results from AGC modeling.

Cyclostratigraphic analyses of stratigraphically complete successions deposited in deep intrashelf basins of northern Germany indicate that late Early Cenomanian to Middle Turonian depositional sequences DS Ce 3 to DS Tu 3 all more or less contain an identical number of ca. 60 precession couplets (~20 kyr) bundled into twelve short- (~100 kyr) and three long-eccentricity cycles (~400 kyr). This observation suggests a sequence duration of 1.2 myr with regularly recurring amplified sea-level falls every 2.4 myr (major unconformities SB Ce 3, Ce 5, Tu 2 and Tu 4). This strongly supports long-term amplitude modulation cycles of the Milankovitch oscillations as triggers for the formation of Cenomanian–Turonian 3rd-order sequences, i.e., the long-period modulation of obliquity (1.2 myr) and eccentricity (2.4 myr).



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GEOCHEMICAL AND MICROFAUNAL RECORDS OF ENVIRONMENTAL CHANGES IN FLYSCH SEQUENCES – A CASE STUDY FROM THE

BARREMIAN–ALBIAN OC–RICH DEPOSITS OF THE SILESIAN NAPPE (POLISH OUTER CARPATHIANS)

Wójcik-Tabol, P. & Malata, E.

Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, 30-063 Kraków, Poland; e-mails: [email protected]; [email protected]

In the Polish Outer Carpathians the most complete sequence of the Lower Cretaceous sediments with higher OC concentration are know from the Silesian Nappe. The upper Barremian–Albian OC-rich flysch deposits of the Hradište, Veřovice and Lhoty formations, exposed in the upper flow of the Lipnik creek, westwards from Bielsko Biała town, were the subject of detailed geochemical investigations to show environmental changes by means of geochemical indicators (Wójcik-Tabol, P., Ślączka, A., in press). Detailed biostratigraphical data available from the Lipnik section (Geroch and Nowak, 1963) allow to make an attempt to analyse the relation between geochemical and microfaunal episodes within the 500 m thick sequence, including laminated, black shales rich in organic carbon (LOM facies), whose deposition was mainly controlled by the turbidity current activity. Within the studied succession increasing contents of total organic carbon (TOC) is typical of the Veřovice Fm, whose non-calcareous black shales are enriched with iron. The Taxy Episode at the Barremian/Aptian boundary is marked by higher concentrations of nutrient-like elements (P, Ba, Ag, Cd) and redox-sensitive metals (RSTE: Mo, U, Co, V, As). Deposition took place in anaerobic environment with diagenetic pyritization. The early Aptian Selli Episode is emphasis by the rise of TOC and then immediate negative and positive excursions of δ13Corg. Relatively low accumulations of RSTE and bio-activity traces on the sea-floor suggest that conditions were not anoxic. Subsequent peak of TOC and trace metals as well as negative excursion in δ13Corg was recognised as the late Aptian Fallot Episode of environmental changes. Organic matter of mixed continental and marine nature was deposited under anoxic conditions. At the Aptian/Albian boundary, at the top of the Veřovice Fm, the organic matter accumulation and positive excursion in δ13Corg can be linked to the Paquier Episode and OAE 1b. Organic matter supply led to continuing anoxic conditions. The late Albian OAE 1c Tollebuc Event can be recorded in turbiditic sequence of the middle part of the Lhoty Fm. Anoxic conditions according to Detrital-OAE model are the most possible explanation of black shales accumulation within the Lhoty Fm. The Hradište Fm consists of mixed assemblages of calcareous and agglutinated foraminifera with Praedorothia hauteriviana and calcitized Radiolaria. The lower part of the Veřovice Fm is characterized by pyritized Radiolaria and exclusively agglutinated foraminifera with Verneuilinoides neocomiensis and other taxa representing generally infauna morphotypes. The upper part of the Veřovice Fm displays impoverished assemblages of agglutinated foraminifera and lack of Radiolaria. The microfaunal assemblages of the Lhoty Fm consist of Radiolaria and agglutinated foraminifera with Plectorecurvoides alternans and relatively numerous specimens of Haplophragmoides, Recurvoides and Thalmannammina representing mainly surficial epifauna. The most significant change from assemblage with P. hauteriviana to V. neocomiensis correlates with the Taxy Episode at the Barremian/Aptian boundary. The early Aptian Selli Episode seems to coincide with the disappearance of abundant verneuilinids between the lower and upper part of Veřovice Fm. The appearance of assemblage with P. alternans can be linked to the Paquier Episode and OAE 1b.

References

Geroch, S., Nowak, W., 1963. Lower Cretaceous in Lipnik near Bielsko, Western Carpathians (in Polish with English summary). Rocznik Polskiego Towarzystwa Geologicznego 33, 241–263.

Wójcik-Tabol, P., Ślączka, A., in press. Are Early Cretaceous environmental changes recorded in deposits of the western part of the Silesian Nappe? A geochemical approach. Palaeogeogr., Palaeoclimat., Palaeoecol..



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PALAEOENVIRONMENT AND BIOSTRATIGRAPHY OF POSTALM-SECTION, NORTHERN CALCAREOUS ALPS (AUSTRIA)

Wolfgring, E. & Wagreich, M.

Department of Geodynamics and Sedimentology, Althanstraße 14, 1090 Vienna, Austria, e-mail: [email protected]

The Upper Cretaceous Postalm section displays the transition from a shelf to a bathyal environment. Situated in the Northern Calcareous Alps, representing the southern margin of the Penninic Ocean, this section exhibits Santonian deposits assigning to the Bibereck Formation and upper Santonian to upper Campanian strata assigning to the Nierental Formation. Cyclic marl - marly limestone alternations set in at the fully pelagic Nierental Formation, while the stratigraphically older part of Postalm section displays heavily bioturbated marlstones, with a highly diverse palaeofauna, rich in benthic foraminifera. We can observe a distinct deepening in the lower Campanian reflected by the dominance of planktic foraminifera (more than 90% of the total foraminifera assemblage) and a benthic foraminifera community showing similarities to the slope-marl assemblage type.

Over 300 samples were taken bed-by-bed to provide a per-cycle resolution. Upon examination of the planktic foraminifera biostratigraphy, we can identify an almost complete succession from the Santonian Dicarinella asymetrica Zone to the late Campanian Gansserina gansseri Zone (nannofossil zones CC 17 to CC 22). The lower Globotruncanita elevata Zone shows a discontinuous record at Postalm section. The lowest occurrence of Contusotruncana plummerae as well as Globotruncana ventricosa can be recorded in a presumably continuous sedimentary interval. The middle to late Campanian Radotruncana calcarata Zone has been investigated in detail and provides a reliable marker. Towards the uppermost Campanian we experience frequent turbidite events in the G. gansseri Zone.

The study of Wagreich et al. (2012) outlines the intense investigation of the R. calcarata Zone at Postalm; Biostratigraphic data combined with a cyclostratigraphic examination provides a chronostratigraphic framework for this interval. Cyclic marly limestone - marl alternations, as well as isotope data and variations in carbonate content provide the basis for a cyclostratigraphic assessment. Based on the 405 kyr eccentricity cycle, data from the Gta. elevata, G. ventricosa or C. plummerae and the G. havanensis Zone show strong signals for obliquity and precession cycles, thus allowing to establish a cyclostratigraphic record for larger parts of the Campanian at Postalm section.

To determine the exact durations of biozones in the Campanian and to date stratigraphically important events, cyclostratigraphic results from Postalm section will be correlated with other Campanian sections via biostratigraphy and isotope data. For a precise calibration of the record and the establishment of an astronomical timescale, the impact of faults and gaps on the record at Postalm has to be identified.

References

Wagreich, M., Hohenegger, J., Neuhuber, S., 2012. Nannofossil biostratigraphy, strontium and carbon isotope stratigraphy, and an astronomically calibrated duration of the late Campanian Radotruncan calcarata Zone. Cretaceous Research 38, 80-96.



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RECORDS OF LATE CRETACEOUS TECTONICALLY ENHANCED SEQUENCE BOUNDARIES AND SHORT-TERM SEA LEVEL CHANGES, SE TURKEY,

ARABIAN PLATFORM Yılmaz, I. O1. & Hosgor, I.2

1Department of Geological Engineering, Middle East Technical University, 06800, Ankara, Turkey, e-mail: [email protected] 2Viking International Ltd., Çankaya-Ankara, Turkey

In SE Turkey, the exposed and drilled carbonate successions display cyclic alternation of facies in meter-scale, and laterally may show variations along the Arabian platform.

In Cenomanian, the studied Derdere Formation displays alternation of benthic foraminiferal, algal packstone/wackestone and bioclastic wackstone/limemudstone at the top and alternation of bivalve wackestone/packstone and limemudstone with planktonics or dolomitic limestones/dolostone facies at the bottom. This large-scale cyclic facies variations from bottom to top in a shallowing upward structure indicate a large-scale control in behind.

In the Santonian-Maastrichtian interval, in SE Turkey, drowning of the platform carbonates indicates a tectonic control in behind related to sudden subsidence and phosphate deposits take place just over the platform carbonates within pelagic facies. Within the Campanian, carbonate successions display alternation of bioclastic packstones/wackestones and chalky facies or alternation of calciturbidites and chalky facies in some places. Successions are covered by thick-bedded reefal carbonates including rudists, oestrea, pelecypoda and bryozoa. This large-scale shallowing upward structure indicates a tectono-sea level change.

In published studies, in NE and SW of Iraq, South and Central Jordan and Syria, the Cenomanian-Turonian shallow water carbonates are drowned and overlying succession belonging to Coniacian-Santonian-Lower Campanian intervals display pelagic marls and phosphate deposits. In wells located at the offshore Kuwait, a sequence boundary can be observed in around the Cenomanian/Turonian boundary.

In SE Turkey, there are tectonically enhanced sequence boundaries around the Cenomanian-Turonian boundary and in the Campanian, which are followed by drowning and covered by pelagic marls and carbonates.

Tectono-sea level changes can be observed in large-scale and with relatively bigger time gap on the Arabian plate, however small-scale cycles can represent climate/oceanographic/tectono-oceanographiic changes.

Key levels of global Campanian and Cenomanian/Turonian black shales may help to investigate and analyze the tectono-sea level and eustatic changes.



46

RESPONSES OF CARBONATE PLATFORMS TO SEA LEVEL CHANGES: EXAMPLES TO EUSTATIC AND TECTONIC CONTROLS IN CRETACEOUS

SEA-LEVEL CHANGES, THE CENTRAL TAURIDE AND PONTIDE PLATFORMS Yılmaz, I. O. & Altiner, D.

Department of Geological Engineering, Middle East Technical University, 06800, Ankara; e-mail: [email protected]

The Tauride and Pontide platforms were separated by the northern branch of Neo-Tethyan Ocean, therefore their different characteristic features can be reflected within the successions.

In the Tauride platform, small-scale meter-scale cycles display shallowing upward peritidal carbonate cycles capped by subaerial features such as mudcracks, dissolution vugs and microkarstic mantling breccias.

The karstification effected the max.1-2 meters depth of the cycles. Therefore it can be stated that these kind of sea-level falls are short-term and in the order of meters and do not include any significant tectonic contribution.

In the Aptian, the sequence boundaries are generally represented by karst breccia and can be correlated in long distance. These levels also correspond to disappearing of some benthic microorganisms and interpreted as type-1 sequence boundary.

Bauxite deposits lying on the “Cenomanian-Turonian” peritidal carbonates and infilling the paleokarst dolines reaching to 150 m in some places are overlain by “Santonian-Campanian” rudist bearing shallow water carbonates. Laterally, this karst surface may thin up and form relatively thinner surfaces.

Polygenic conglomerates including limestone pebbles derived from the underlying rock units are overlain by Maastrichtian shallow water carbonates. This conglomerate facies is few meters in thickness and can be correlated in the NW-SE direction along the Tauride platform. These types of tectonically controlled sea-level changes can be stated as 1st or 2nd order.

The Cenomanian to Turonian bauxite and Campanian to Maastrichtian polygenic conglomerate facies display a tectonically controlled sea level change whereas cyclic meter-scale facies changes within Berriasian to Albian are eustatic sea level changes. Tectonically controlled sea level changes display millions of year time gap at the exposure surfaces, however eustatic sea level changes present thousands of years time gaps at exposure surfaces and generally in meter-scale. They can be interpreted as 4th or 5th order sea level changes.

In Pontide platform, in the Barremian-Aptian interval, small-scale meter-scale cycles display alternation of peritidal carbonate facies and calcareous marine sandstones. Marine sandstones include daysclad algae and benthic foraminifera, quartz sands cemented by calcite. Sandstones are overlain by carbonates in a cyclic pattern and some cycles are capped by dissolution vugs and charophyta levels.

In some places, alternation of rudist bearing bioclastic carbonates with conglomerates and sandstones can be seen. Within the Aptian, drowning of the platform was followed by black shale deposition including ammonites, pyrite and glauconite minerals. This drowning can be parallel with Europian basins.

However, this Aptian drowning and clastic contribution in cyclicity is not seen in the Tauride platform. Fisher plot analysis and amplitude of the cycles display clear difference between two platforms and indicate more subsidence control in the Pontides than Taurides.

Climatic/Eustatic sea-level changes are reflected in small-scale variations and tectonic control has been generally observed in large-scale as prolonged exposures or drowning of platforms with overlying pelagic troughs. Tectonic control in small-scale sea-level changes has been reflected in types and amplitudes of the small-scale cycles in different platforms.



47

MODELLING OF ACCOMMODATION AND SILICICLASTIC SEDIMENTATION MECHANISMS IN PLATFORMAL SEDIMENTARY BASINS

Zorina, S.O.1,2 1 Central Scientific Research Institute of Geology of Industrial Minerals, Zinin str. 4, 420097 Kazan, Russian Federation e-mail: [email protected] 2 Kazan Federal University, Kremljevskaya street 18, 420008, Kazan, Russian Federation e-mail: [email protected]

It is well known that the interaction between eustasy and tectonic vertical movements is responsible for changes in the regional sea level and, consequently, basin deepening or shoaling, on the one hand, and for transformation of the spatial basin configuration with its expansion or reduction, i.e., transgression or regression, on the other. These factors (regional sea level fluctuations and transgressive–regressive regime of the basin) together characterize the accommodation space available for sediments. Variations in the accommodation space and the influx of sedimentary material (sedimentation factor) determine the structure of the formed sedimentary succession, being responsible for its architecture.

According to the sequence stratigraphy concept (Catuneanu, 2002; Catuneanu et al., 1998; Einsele, 2000, etc.) there are different types of sedimentary successions with distinct vectors of changes in the grainsize composition of sediments through the section: (1) progradational with regressive overlap (2) retrogradational with transgressive overlap; and (3) aggradational lacking grainsize gradient. It should be noted that retrogradational and progradational parasequence sets are not always direct results of respective transgressions and regressions, respectively.

The proposed simple models (Zorina, 2014) demonstrate that retrogradational parasequence sets may accumulate in basins deepening during regressions and in those shoaling during transgressions. The regressive successions are also not necessarily deposited during basin shoaling and regressive phases. The formation of progradational parasequence sets may result from synregressive deepening of the basin and its syntransressive shoaling as well.

Many examples of the above mentioned depositional environment may be identified in the Middle Jurassic - Lower Cretaceous sequences on the Eastern Russian Plate. For instance, syntransgressive shoaling is responsible for the formation of the Lower Bathonian sandy strata and the Jurassic-Cretaceous bituminous boundary clays (Zorina, 2014).

Taking into consideration the diversity of scenarios leading to the formation of progradational and retrogradational parasequence sets, there are grounds to believe that this process could be expected in any accommodation–sedimentation environment, when variations in these factors are comparable.

Thus, the models proposed in this communication to supplement the theoretical basis of sequence stratigraphy offer the opportunity to widen the spectrum of probable scenarios and consequences of interaction between global eustasy, tectonic vertical movements, and the depositional gradient and amend our understanding of the factors responsible for sedimentation in platformal basins.

References

Cătuneanu, O., 2002. Sequence stratigraphy of clastic systems: concepts, merits, and pitfalls. Journal of African Earth Sciences. 35, 1-43.

Cătuneanu, O., Willis, A.J., Miall, A.D., 1998. Temporal significance of sequence boundaries. Sedimentary Geology. 121, 157-178.

Einsele, G., 2000. Sedimentary Basins: Evolution, Facies and Sediment Budget. Springer-Verlag, Berlin, 792 pp. Zorina, S.O. 2014. The Sediment Accommodation Space and Sedimentary Successions in Platformal Basins:

Mechanisms of Formation. Doklady Earth Sciences 455, 399-402.

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