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Abstracts / Quaternary International 279-280 (2012) 346–461448
of cosmogenic age determination (e.g. geomagnetic corrections) meansthat while we have millenial scale precision on ages during the LGIT, theaccuracy of the ages is not as high. Nevertheless, our data clearlydemonstrate that the evacuation of ice from these east coast valleys in NewZealand was remarkably slow with glaciers extending to w60% of theirLGM extents at 14 kyr (or younger). There is no evidence for either an earlyLGIT ice collapse or rapid retreat and consequently no late LGIT majorreadvance. We contrast our findings with the interpretations of chronol-ogies coming from the Mackenzie Basin and we conclude that the recordsare compatible, with the chronological differences created by themorphometry of the respective ice catchments.
CLIMATE (ENSO AND PDO) RECORDS FROM AUCKLAND MAARS, NEWZEALAND
James Shulmeister. University of Queensland, AustraliaE-mail address: [email protected]
We present the results of spectral analyses of laminae records fromAucklandmaar lakes covering the early and late Holocene. The laminae areorgano-diatomaceous and reflect biological productivity in the closedmaar lakes. It can be demonstrated that the likely source of laminaevariability is due to nutrient limitation and that this is related towind flow.A significant component of the nutrient flux is derived from Australiandust.All the records display a similar pattern with long intervals of no spectralpower interspersed with shorter, decadal to centennial scale intervals ofstrong spectral coherence. In all cases spectral power has periodicities inthe 15–30 year range and at about 50–70 years consistent with PacificDecadal Oscillation (PDO) periodicity. For quasi-annual records strongspectral power is present at 5–7 year and 18 month–3 year periods,consistent with El Niño Southern Oscillation (ENSO).Some of the records are quasi-annual while others are at close to decadalresolution with laminae frequency increasing from the early to the lateHolocene, which we relate to increased seasonality in the SouthernHemisphere. The increasing frequency of laminae from the early to late theHolocene runs in tandem with increasing spectral power in short-frequency (18 month–3 year) ENSO signal and is consistent with ENSOrecords from the tropical Pacific and South America. There is a knownrelationship between –ve ENSO events and SW wind flow anomalies, overthe Auckland region. Similarly there is a relationship between +ve PDOphases and (south) westerly flow over New Zealand. We propose that thebrief episodes of strong spectral coherence over the Auckland regioncoincide with in phase relationships between +ve PDO and –ve ENSOevents. The brief interludes of strong spectral power suggest that eitherthese relationships are non-stationary, or that a further external forcing isinvolved, or most likely a combination of these factors.
MARINE AND TERRESTRIAL ECOSYSTEM RESPONSE ONPALAEOCLIMATIC CHANGES IN THE BLACK SEA REGION
Ludmilla Shumilovskikh. University of Göttingen, GermanyE-mail address: [email protected]
Marine and terrestrial ecosystems respond to climate change in differentways. Deciphering the relationship between both systems in the Black Seaarea by using different proxies during two last glacial terminations andfollowing interglacials is the aim of this study. Choice of the Black Sea asresearch area was based on its sensitivity to past global and regionalclimatic changes, as well as the lack of long and continuous records.Marine cores 22-GC3 and 22-GC8 from SE Black Sea cover the last 140 kyrBP and are studied by high resolution analysis of pollen and dinoflagel-lates to reconstruct vegetation and hydrological changes in the region.Age-control of the time series is based on shell oxygen isotops (ostracods,bivalve) correlated to the isotope records of Uranium series datedstalagmites from Solufar Cave, NW Anatolia. This close link betweenoxygen isotope records from Black Sea sediment cores and Anatolianspeleothemes has been demonstrated earlier. During glacial periodssteppe vegetation dominated, which was replaced by oak steppe forestand then by more humid forest vegetation (Fagus, Carpinus). During both
interglacial periods corresponding to the Holocene and Eemian, Medi-terranean – Black Sea reconnection took place, inducing transition fromfresh / brackish to more marine conditions. Patterns of vegetation andhydrological changes during interglacials are not identical. In opposite toHolocene, summer dry vegetation dominating during the first half ofEemian was replaced by more humid in the second part. Sea surfacetemperature and salinity achieved significant higher values in Eemian incompare to the Holocene. The stalagmites from Solufar Cave located atthe southern Black Sea coast provide palaeorecords of vegetation andprecipitation through their oxygen and carbon isotopic composition. Adetailed comparison of the sediment and stalagmite proxies will becarried out in this study and will provide the climatic frame for theregion.
ESTIMATION OF THE SEA-SURFACE RESERVOIR 14C AGES OFF THESOUTH CHILEAN MARGIN SINCE THE LATE GLACIAL PERIOD
Guiseppe Siani. Laboratoire "Interactions et Dynamique des Environ, FranceE-mail address: [email protected]
The southern Chilean continental margin off the Aysen Fjords region issituated within a zone of high precipitation (driven by the southernwesterly wind belt), generated by the ocean–atmospheric control of theSouthern Polar Front that moves seasonally between 50�S (summer) and40�– 45�S (winter). It is also a zone of important volcanic activity in theAndes chain marked by thirteen Quaternary large volcanic centers,forming the southern volcanic zone (SVZ). Hence, this region constitutesa key zone to better understand the variability of the atmospheric andoceanic circulation systems in the southern hemisphere and to elucidatetheir roles in climate changes at regional and global scale. For this topic,we have selected a long CALYPSO high sedimentation piston core MD07-3088 collected off the south Chilean margin between the northernChonos archipelago and southern Taitao peninsula at about 46�S duringthe IMAGES R/V Marion Dufresne cruise Pachiderme (February 2007).We present here preliminary results dealt on quantitative estimates ofpast sea surface reservoir 14C ages, necessary to establish a commonchronological framework for marine, continental and cryospheric pale-oproxies, and crucial to understand the ocean-atmosphere climaticsystem. AMS 14C dates of tephra, contemporaneously deposited overthe Northern Patagonia marine and terrestrial regions reveal that sea-surface reservoir 14C ages range at 1320 and 975 years during thedeglaciation and before the Antarctic Cold Reversal period respectively.By contrast, sea-surface reservoir 14C ages decrease at the onset andduring the upper Holocene and were estimated at 920 and 790 yearsrespectively.
INTERGLACIAL SEA-LEVEL CHANGE AND EQUILIBRIUM SEA LEVEL:IMPLICATIONS FOR FUTURE SEA-LEVEL PREDICTIONS
Mark Siddall. University of Bristol, United KingdomE-mail address: [email protected]
What characterizes Quaternary inter-glacial sea level with reference toearlier periods and glacial periods? Do sea-level similarities between inter-glacials indicate a robustness of the ice sheets or do differences indicatethat ice sheets are sensitive to subtle differences in climate?What does ourcurrent knowledge of the magnitude and stability of sea level during inter-glacials have to tell us about ice sheets during periods warmer than today?This talk will attempt (not claiming success!) to give context and analysisof our current knowledge and discuss potential clues for future change.
REDUCING THE VARIABILITY IN AMINO ACID RACEMIZATION ANALYSISOF THE UBIQUITOUS FORAMINIFERA NEOGLOBOQUADRINAPACHYDERMA
Katherine Sides. Northern Arizona University, United StatesE-mail address: [email protected]
The planktonic foraminifera Neogloboquadrina pachyderma (s) is commonin marine sediment from high latitudes, making it a preferred species for
