Following the unanimous recommendation of the Inter-national Commission on Stratigraphy, the Globalboundary Stratotype Section and Point (GSSP) for thebase of the Cenomanian Stage is defined at a level 36metres below the top of the Marnes Bleues Formation, alevel that corresponds to the the first appearance of theplanktonic foraminiferan Rotalipora globotruncanoidesSigal, 1948, on the south side of Mont Risou, east ofRosans, Haute-Alpes, France, where it can be placed inthe context of a series of secondary marker levels basedon nannofossils, planktonic foraminifera, ammonites,and an ornate δ13C curve.

Introduction

The present document defining a Global boundary Stratotype Sec-tion and Point (GSSP) for the base of the Cenomanian Stage of theUpper Cretaceous arises from the recommendations of the Ceno-manian Working Group of the Subcommission on CretaceousStratigraphy at its meetings during the Second International Sympo-sium on Cretaceous Stage Boundaries held in Brussels from Sep-tember 8–15, 1995.

The proposal was subsequently submitted to the Subcommis-sion of Cretaceous Stratigraphy, which voted 18 yes, abstain 2. Arevised proposal was submitted to the International Commission onStratigraphy, which voted unanimously in favour of the proposal.The International Union of Geological Sciences was requested toratify this decision; the proposal was finally ratified on 10 December2001.

Historical background

When Alcide d’Orbigny began to divide up the Cretaceous systeminto stages, he at first recognized only two in what is now known asthe Upper Cretaceous: the Turonian and Senonian (Paléontologiefrançaise, Terrains Crétacés, II Gastropodes, pp. 403–406). Withrespect to the Turonian, his words are: “je propose de désigner àl’avenir l’étage qui m’occupe sous le nom de terrain Turonien, de laVille de Tours (Turones) ou de la Touraine (Turonia), situées sur cesterrains” (d’Orbigny, 1842-1843, p. 405), defining the Turonian asequivalent to the Craie Chloritée, Craie tuffeau, Glauconie crayeuse,

Grès Vert Supérieur etc., and taking the name from Touraine(Roman Turonia). Five years later, he realized that two distinctammonite and rudist faunas were present, and he restricted the termTuronian to beds corresponding to his third zone of rudists, yielding“Ammonites lewesiensis, peramplus, Vielbancii, Woolgari, Fleuri-ausianus, Deverianus etc.”, “le plus beau type côtier étant trèsprononcé dans toute la Touraine, et nous donnerons à la partieinférieure le nom d’étage Cénomanien, le Mans (Cenomanum), enmontrant à la fois le type sous-marin” (d'Orbigny, 1848–1851, p.270).

In the second volume of Prodromed’Orbigny (1850) listed 809species as characteristic of the Cenomanian, 46 of them ammonites,of which 10 were specifically cited from Sarthe, in which Le Manslies. Localities mentioned are Saint-Calais, Le Flèche, Cérans,Ecommoy, Grand Lucé, Coudrecieux, Vibraye, Lamnay and LaFerté-Bernard.

Faunas from the Cenomanian of Sarthe were described byGuéranger (1867) in his Album paléontologique du département dela Sarthe, one of the earliest publications with photographs of fos-sils, and the stratigraphy was investigated in particular by Guillier(1886). The ammonites were then neglected for almost 100 years,until Hancock (1960) listed all the stratigraphically localized Ceno-manian ammonites he was able to trace in the Le Mans and ParisCollections, as well as new material collected by him, a total of 161specimens. This work forms the basis of all subsequent studies.

It is to the researches of Pierre Juignet and his collaborators thatour present knowledge of the Cenomanian Stage in the environs ofLe Mans stems; see in particular Juignet (1974, 1977, 1978), Juignet,Kennedy & Wright (1973), Kennedy & Juignet (1973, 1977, 1984,1983, 1994a, 1994b), Juignet, Kennedy & Lebert (1978), Juignet etal. (1984) and Robaszynski et al. (1998).

From these works it has become recognized that the paucity ofexposure in the environs of Le Mans makes it unlikely that a bound-ary section could ever be designated in the historical type area of thestage.

The Global boundary Stratotype Section and Point for the base of theCenomanian Stage

Location

The GSSP is located on the western flanks of Mont Risou (1183m), in NE-SW trending gullies in badlands, 3.15 km east of the cen-tre of the town of Rosans, Hautes-Alpes, France (Figures 1–3),

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by W.J. Kennedy1, A.S. Gale2, J.A. Lees3, and M. Caron4

The Global Boundary Stratotype Section andPoint (GSSP) for the base of the CenomanianStage, Mont Risou, Hautes-Alpes, France1 Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, U.K.2 Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BP, U.K. and School of Earth and Environ-

mental Sciences, University of Greenwich, Chatham Maritime Campus, Chatham, Kent ME4 4AW, U.K.3 Research School of Geological and Geophysical Sciences, Birkbeck College and University College London, Gower Street, London WC1E

6BT, U.K.4 Institut de Géologie, Université de Fribourg, CH-1700 Fribourg, Switzerland.

around a point 5° 30’ 43” E, 44° 23’ 33” N (Lambert II Zone coordi-nates 852.725; 1937.625), on the 1:25,000 French Série Bleue1:25,000 Sheet 3239 Ouest, Rosans (Gale et al. 1996).

The boundary lies 36 m below the top of a thick sequence ofconstantly eroding marls, the Marnes Bleues of French workers, butcan be located in the field in relation to the first limestone that definesthe base of the overlying, unnamed unit of limestone-marl alterna-tions (Figures 3, 4) (this limestone marker bed was taken as the baseof the Cenomanian by Moullade (1966), and Porthault (1974, 1978)in their classic studies of the Cretaceous of the Vocontian Basin).

Access

The GSSP can be reached by taking the D994 road east fromRosans, and turning south on the D949 (signpost: St. André-de-Rosans). Beyond the buildings at Notre Dame, the road describes ahairpin bend, and crosses the Lidane stream. Just east of the 668 mspot height a track leads left (NNE) up the lower slopes of MontRisou: the gullies that encompass the GSSP are easily accessible onfoot.

Description of the GSSP

The Global boundary Stratotype Section and Point for the baseof the Cenomanian Stage is the level 36 m below the top of theMarnes Bleues that corresponds to the first occurrence (FO) of theplanktonic foraminifer Rotalipora globotruncanoidesSigal, 1948, inthe Marnes Bleues Formation. This can be most readily located inthe field by measuring down from the base of the lowest limestone ofthe overlying unnamed limestone-marl unit of Cenomanian age (Fig-ure 3). A detailed log of the sequence is shown in Figure 4.

The GSSP succession in the top 136 m of the Marnes BleuesFormation is of marls with varying carbonate and organic carboncontent. Levels with higher carbonate content weather out as slightlymore resistant levels, as indicated on the logs. Levels of higherorganic carbon content are frequently laminated, and are againslightly more resistant to weathering. Bréhéret (1988a, 1988b, 1997)has recognised a series of such levels in the Marnes Bleues of theVocontian Basin, and assigned names to the more important. Thehighest of these marker beds, the Niveau Breistroffer (BreistrofferLevel) occurs 135 to 124 m below the top of the GSSP, and is theonly prominent marker in the section below the zero datum at thebase of the unnamed formation that overlies the Marnes Bleues.

The Niveau Breistroffer is well exposed immediately beneath astream junction. It comprises decimeter- to meter-scale alternations

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Figure 1 Locality map for Mont Risou, Hautes-Alpes, France.

Figure 2 Locality map for the Global boundary Stratotype Sectionand Point for the base of the Cenomanian Stage, on the westernslopes of Mont Risou, east of Rosans, Hautes-Alpes, France.

Figure 3 Outcrop photographs of the Global boundary StratotypeSection and Point for the base of the Cenomanian Stage, on thewestern slopes of Mont Risou, east of Rosans, Hautes-Alpes,France. A – Distant view of Mont Risou from the south. Thesummit ridge is formed by Turonian limestones. The MarnesBleues and succeeding un-named unit crop out in badlands eastand west of the zig-zag track. B – Typical outcrop of the GlobalBoundary Stratotype Section and Point for the base of theCenomanian stage. A: marker limestone bed, the base of whichdefines the upper limit of the Marnes Bleues; B: the GSSP, 36 mbelow the top of the Marnes Bleues Formation.

of more or less calcareous, dark grey bioturbated marl, and five bedsof dark, laminated marl that are relatively organic-rich. The secondlaminated layer is 0.5 m in thickness, and contains a diverseammonite fauna and infrequent bivalves. A similar, but slightly lessabundant ammonite fauna is found in the third and fourth laminatedlayers.

Above the Niveau Breistroffer are 12 m of grey, bioturbated,poorly fossiliferous marls (−123 to −135 m) containing an impersis-tent bed of barytes — cemented concretions. The overlying 31 m ofmarls (−92 to −123 m) are rhythmically bedded on a meter scale,and limited macrofaunas were collected. At −80 m is a bed contain-ing abundant ammonites, notably heteromorphs.

The boundary level: primary and auxiliarybiostratigraphic markers

Three groups provide the principal biostratigraphic markers forthe boundary interval: ammonites, planktonic foraminifera, and nan-nofossils, with inoceramid bivalves (which are poorly represented inthe Marnes Bleues) as a further group. Figure 5 shows the occur-rence data for ammonites in the sequence, Figure 6 the data forplanktonic foraminifera, and Figure 7 the nannofossil data.

The distribution of key faunal and floral events across theAlbian-Cenomanian boundary in the Marnes Bleues succession atthe Mont Risou GSSP are plotted in Figure 10, and are, from oldestto youngest:

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Figure 4 Detailed lithostratigraphiclog of the upper 150 m of the MarnesBleues Formation, and the base of thesucceeding un-named unit at theGlobal boundary Stratotype Sectionand Point for the base of theCenomanian Stage, on the westernslopes of Mont Risou, east of Rosans,Hautes-Alpes, France.

Base of the Niveau Breistroffer: − 135 m.

● The last occurrence of the planktonic foraminiferan Rotali-pora subticinensis at −132 m.

● The last occurrence of the nannofossil Hayesites albiensis,also at -132 m.

● The last occurrence of species of the ammonite genera Mor-toniceras (Durnovarites)and Cantabrigites, also at −132 m.

● The first occurrence of the nannofossil Arkhangelskiella ante-cessorat −128 m.

Top of the Breistroffer Level: −124 m.

● The first occurrences of the nannofossils Gartnerago chiastaand Crucicribrium anglicumat −124 m, (local events).

● The last occurrence of the planktonic foraminiferan Planom-alina buxtorfiat −116 m.

● The last occurrence of the planktonic foraminiferan Costel-lagerina libycaat −112 m.

● The last occurrence of the nannofossil Arkhangelskiella ante-cessorat −80 m.

● The first occurrence of the planktonic foraminiferan Rotali-pora tehamaensisat −48 m.

● The last occurrence of the planktonic foraminiferan Rotali-pora ticinensisat −40 m.

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Figure 5 Distribution of ammonites and inoceramid bivalves in the top 80 m of the Marnes Bleues Formation and the base of thesucceeding unnamed unit at the Global boundary Stratotype Section for the base of the Cenomanian Stage on the western flanks of MontRisou, east of Rosans, Hautes-Alpes, France.

● The first occurrence of the planktonic foraminiferan Rotali-pora gandolfii, also at −40 m.

● The first occurrence of the nannofossil Calculites anfractus,also at −40 m.

● The base of the Cenomanian stage is defined as the level 36m below the top of the Marnes Bleues, which corresponds to firstoccurrence of the planktonic foraminiferan Rotaliporaglobotruncanoides.

● The last occurrence of the typically Albian ammonitesLechites gaudini, Stoliczkaia clavigera, Mariellacf. miliaris andHemiptychoceras subgaultinumat −32 m.

● The first occurrence of typically Cenomanian ammonitesNeostlingoceras oberlini, Mantelliceras mantelli, Hyphoplites cur-vatus and Sciponoceras roto at −30 m.

● The common occurrence of the planktonic foraminiferanRotalipora globotruncanoidesat −27 m.

● The last occurrence of the nannofossil Staurolithites glaberat−12 m.

● The first occurrence of the nannofossil Gartnerago thetaat−8 m.

Zero datum, the first limestone in the sequence

● The first occurrence of the nannofossils Gartner-ago praeobliquum(local event) and Prediscosphaeracretaceasensu stricto (local event) at +16 m.

● The first occurrence of the nannofossil Corol-lithion kennedyi at +20 m.

The assemblages of planktonic foraminifera in theinteval studied (−136 to −15m below the top of theMarnes Bleues) show no major faunal change. The morecomplex specimens, typically about 500 microns indiameter, with single keel and supplementary apertureson the umbilical side, are represented by the Rotaliporagroup. They show progressive diversification up the sec-tion, and it is this that provides the basis for biostrati-graphic subdivision and correlation.

The last occurrence (LO) of Rotalipora subtichi-nensisis at −132 m (Figure 6). Above, the assemblagesis characterised by the co-occurrence of Rotalipora tici-nensis and R. appeninica, up to the level of first occur-rence (FO) of R. tehamensisand R. gandolfiiat −40 m.This corresponds to the last occurrence of R. ticinensisinthe Risou section. The first occurrence (FO) of Rotali-pora globotruncanoidesat −36 m marks the base of theCenomanian stage. These four species of Rotalipora(globotruncanoides, appenninica, tehamensis,gandolfii) coexist from −36 m to −19 m, and form a sub-zonal association that is a useful indicator for the base ofthe stage.

The gradual evolution of the polyphyletic Rotali-pora group (cf. Gonzalez Donoso in Robaszyski et al.,1994, p. 428) can be followed through the interval stud-ied. Two lineages that arose during the late Albian arepresent at the base of the section. The first, representedby Rotalipora subticinensis, arose from Ticinellapraeticinensisby acquisition of a peripheral keel, givingrise to Rotalipora subticinensis, which gave rise in turnto R. ticinensis. This last named gave rise, in turn, to R.tehamensis(−48 m), and R. globotruncanoides(−36m). The second lineage arose from Ticinella raynaudi,and is represented by Rotalipora appenninicaand R.gandolfii (−40 m).

These two lineages are readily traced in the presentsuccession on the basis of a series of intermediate forms,marked by an asterisk in Figure 6, which occur in thetransitional intervals in which the new species arose.

In a broader context, the Ticinella praeticinen-sis–Rotalipora subticinensis–R. ticinensis–R. globotruncanoides–R.greenhornensislineage is of great value in Upper Albian to UpperCenomanian biostratigraphy, showing gradual progressive changes,a feature that strengthens the case for the selection of the first occur-rence of Rotalipora globotruncanoidesas the key biostratigraphicmarker for the base of the Cenomanian stage.

The major faunal change in the ammonite fauna occurs between−30 and −32 m, with the disappearance of typical Albian taxa at −32m and the appearance of typical Cenomanian taxa at −30 m. Nineammonite taxa pass across the boundary; they are long-rangingdesmoceratids, puzosiids, phylloceratids and gaudryceratids of typi-cally Tethyan aspect. There is no lithological break or change in theintervening 2 meters between the last Albian and the first Cenoman-ian ammonites. The Albian-Cenomanian boundary, as seen at Risou,is marked by a sudden turnover of about 65% of ammonite taxa.Several of the changes presumably reflect evolutionary transitionswhich occurred rapidly elsewhere (Stoliczkaia clavigera→Mantel-liceras mantelli; Lechites gaudini→∗ Sciponoceras roto), with sub-sequent migration into the area. See Appendix II for further detailson ammonites, nannofossils, and planktonic foraminifera in thesequence.

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Figure 6 Distribution of planktonic foraminifera in the top 136 m of the MarnesBleues Formation at the Global boundary Stratotype Section for the base of theCenomanian Stage on the western flanks of Mont Risou, east of Rosans, Hautes-Alpes, France. See text for discussion.

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Figure 7 Distribution of calcareous nannofossils in the top 136 m of the Marnes Bleues Formation at the Global boundary StratotypeSection for the base of the Cenomanian Stage on the western flanks of Mont Risou, east of Rosans, Hautes-Alpes, France.

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Key:Nannofloral abundance (qualitative): H = High, M = ModerateNannofloral preservation: M = Moderate (identification of specimens with the light microscope not hampered by diagenetic

etching and overgrowth of calcite).Taxon abundance: A = Abundant (> 10 specimens/field of view)

C = Common (1–10 specimens/field of view)F = Few (> 3 specimens/traverse)R = Rare (1–2 specimens/traverse)

(Continued)

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Figure 8 Key planktonic foraminiferal taxa from the Global boundary Stratotype Section for the base of the Cenomanian Stage on the western flanks of Mont Risou, east of Rosans, Hautes-Alpes, France.

1–3, Rotalipora appenninica (Renz), BMNHS, −136 m; 4–6, Rotalipora gandolfii Luterbacher & Premoli-Silva , BMNHS, −38 m; 7–9, Rotalipora tehamaensis Marianos & Zingula , BMNHS, −27 m; 10–12, Rotalipora globotruncanoides Sigal, BMNHS, −36 m; 13–15, Rotalipora globotruncanoides Sigal, BMNHS, −23 m; 16–18, Rotalipora ticinensis (Gandolfii), BMNHS, −136 m. (Bar scale is 100 microns)

Carbon and oxygen stable isotopestratigraphy of the boundary interval

Oxygen isotopes

The δ18O curve for the Mont Risou sec-tion (Figure 9) shows small-scale variation ofthe order of 0.3‰ for much of the lower,Albian, part of the succession, values mostlyfalling between −3.8‰ and −4.1‰. In theCenomanian part of the section above, valuesrise to a maximum of −3.5‰. The possibilitythat these values have been altered by the addi-tion of isotopically light cement during burialdiagenesis has to be considered, because theMarnes Bleues in the Vocontian Basin havebeen buried to a depth of up to several kilome-ters. The primary nature of these results is sup-ported by several lines of evidence. SEMinspection of broken surfaces of variouslithologies reveals little obvious cement:foraminiferan tests are empty, for example.The δ18O values translate to give sea water sur-face temperatures of 26–27°C, using the equa-tion of Anderson & Arthur (1983 SMOW1.2‰) which are reasonable for this latitude inthe Late Albian to Early Cenomanian interval(cf. Jenkyns, Gale & Corfield 1994). There isno correlation between lithology and δ18O val-ues; indeed, the highest part of the successioncontains carbonate cemented beds, yet yieldsheavier oxygen isotope values — opposite tothe predicted diagenetic trend. Finally, the verylow level of variance is itself suggestive of aprimary signal, because significantly alteredsuccessions are generally noisy as a result ofthe patchy distribution of cement. The oxygenisotope data thus indicates a slight cooling ofabout 1°C, beginning during the earliest Ceno-manian.

Carbon isotopes

δ13C in carbonate sediments is relativelystable and more likely to survive the effects ofburial diagenesis than are oxygen isotopes.However, the bacterial degradation of organicmatter can have a marked effect on the δ13Cratios of the dissolved bicarbonate reservoir,and may result in the formation of cementsenriched in δ12C (Scholle & Arthur 1980;Marshall 1992). Such cements are relativelycommon in deeper water organic-richmudrocks (Marshall 1992) and are potentiallyimportant in interpretation of the d13C datafrom Mont Risou, because the deep-watermarls at this locality contain up to 50% clayand have TOC values of 1–2% (Bréhéret &Delamette 1989, Fig. 2). The Niveau Breistrof-fer (containing laminated horizons) has thehighest TOC values in the succession studied,and registers δ13C values of the order of1.5–1.9‰, which are not significantly lighterthan values from coeval carbonate successions(e.g. Jenkyns et al. 1994). Additional evidencefor a primary δ13C signal in the Mont Risousection comes from the lack of correlationbetween lithology and carbon isotope values.

The carbon curve (Figures 9, 10) registers a broad overall peak(maximum values of 2.3 ‰ at −104 m) through much of the MontRisou section, broken into four discrete peaks (lettered A, B, C, D inFigure 10) by sharp, short-lived falls of δ13C of up to 0.8‰. Thesepeaks and troughs do not correspond to lithological changes, aredefined by numerous points, and thus probably represent secularchange (see above). Peak B registers the highest values which pro-

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Figure 9 The δ13C and δ18O curves across the Albian-Cenomanian boundary in theGlobal boundary Stratotype Section on the western flanks of Mont Risou, east of Rosans,Hautes-Alpes, France. Both δ13C and δ18O results are reproducible to better than ± 0.1‰.See Gale et al. (1996) for details of analytical procedures.

Figure 10 The sequence of auxiliary markers, and the stable isotope curves across theAlbian-Cenomanian boundary interval in the Marnes Bleues at the Global boundaryStratotype section for the base of the Cenomanian Stage on the western slopes of MontRisou, Hautes-Alpes, France.

gressively fall through C and D. However, to demonstrate convinc-ingly the primary nature of the Risou δ13C signature, it is necessaryto find similar curves elsewhere (Scholle & Arthur 1980); Gale et al.(1996) compared carbon curves based on bulk carbonate analysesacross Albian-Cenomanian boundary sections for Gubbio, UmbriaMarche, Italy, (Jenkyns et al. 1994, Fig. 10) and for Speeton, York-shire, England (Mitchell & Paul 1994, Fig. 1) both based on whole-rock analyses. The Gubbio curve shows a small but discrete positived13C spike including four minor peaks straddling the Albian-Ceno-manian boundary as defined there by planktonic foraminifera. TheSpeeton curve shows a broad peak over 3–3.5 m of succession in unitRC2 of Mitchell & Paul (1994), made up of four individual sharppeaks and falls, with a total variance of about 0.8‰. The secondpeak is largest and reaches about 1.75‰; the two succeeding peaksare smaller. Mitchell & Paul place the Albian-Cenomanian boundaryimmediately beneath the highest of the four peaks, on evidence fromcalcitic macrofossils and calcitic and arenaceous microfossils.

The Speeton curve is very similar in overall shape, detail ofornament and variation range to that from Mont Risou. The Albian-Cenomanian boundary at Speeton falls in an identical position to thatat Risou, immediately beneath the fourth minor δ13C peak. Such aresult is in line with data from the Cenomanian-Turonian boundary(Gale et al. 1993) where intricate details of the δ13C spike can beinterpolated with faunal and floral events and correlated on an inter-continental scale. However, the similarity between the Mont Risouand Speeton curves is perhaps even more remarkable because thethicknesses of the two sections differ by two orders of magnitude.The apparent lack of ornament on the Gubbio curve may be a resultof the widely spaced sample intervals of 1 m taken by Jenkyns et al.(1994) from what is a thin succession. We conclude that the ornateδ13C curve across the Albian-Cenomanian boundary established atMont Risou provides a further secondary marker for the base of theCenomanian Stage, which lies betweeen peaks C and D of the curve.Figure 10 summarizes the sequence of lithostratigraphic, biostrati-graphic, and stable isotope markers across the boundary section.

Conclusions

The Global boundary Stratotype Section and Point for the base of theCenomanian Stage at Mont Risou, near Rosans fulfils the followingrequirements set out by Remane et al. (1996):

There is exposure over an adequate thickness, and a sufficient timeinterval is represented by the section so that the boundary canalso be determined by interpretation, using auxiliary markersclose to the boundary.

There is continuous sedimentation across the boundary interval,with no evidence of sedimentary breaks or condensation.

The sedimentation rate was high, and successive events that straddlethe boundary are widely separated.

The boundary interval is not disturbed by synsedimentary and sig-nificant tectonic disturbances. The Risou GSSP is terminated atits lower limit by a fault 100 m below the boundary level, andthere is evidence of synsedimentary deformation 130 m abovethe boundary. The intervening interval includes minor faults withsmall displacements, in part of recent origin, but the boundary isnot so disturbed.

There is no metamorphism, nor a strong diagenetic signal.Well-preserved (if crushed) macrofossils, especially ammonites

occur throughout the sequence, as do well-preserved and abun-dant micro- and nannofossils.

There are no vertical facies changes for 36 m above the boundary,and for more than 80 m below the boundary.

The pelagic facies, with cosmopolitan ammonite taxa, plus abun-dant planktonic micro- and nannofossils represents a favourablefacies for long-distance correlation, as does the palaeogeo-graphic setting of the GSSP, in the passage zone between theEuropean Boreal and Tethyan Realms.

The GSSP preserves an excellent d13C and d18O record that pro-vides an auxiliary marker of potential global application in themarine pelagic realm.

The GSSP is readily accessible by road, with free access.The GSSP does not include potential chronometers for radiometric

dating.

We lack a magnetostratigraphic profile for the GSSP, but notethat the Albian-Cenomanian boundary falls within the CretaceousMagnetic Quiet Zone.

Acknowledgements

We thank Professor K.A. Tröger (Fribourg, Germany) for encourag-ing us to complete this submission on behalf of the CenomanianWorking Party of the Cretaceous Subcommission, and are grateful tothe members of the Working Party (see Appendix I) who sent uscomments and suggestions on improving the manuscript. The tech-nical support of the staff of the Geological Collections, Oxford Uni-versity Museum of Natural History, and the Department of EarthSciences, Oxford, is gratefully acknowledged.

Appendix I

Cretaceous Subcommission—Cenomanian Working Group Mem-bership as at 31/3/97

E. Baraboschkin (Russia), P. Bengtson (Germany), J. Burnett(UK), M.M. Carmen (Romania), W. Christensen (Denmark), G.Csaszar (Hungary), A. Dhondt (Belgium), E. Erba (Italy), El M.Ettachfini (Morocco), A. Gale (UK), J. Gallemi (Spain), Gam-bashidze (Georgia), M. Gameil (Egypt), S. Gardin (France),Ghughunshivili (Georgia), J.M. Hancock (UK), J. Ion (Romania),J.W.M. Jagt (Netherlands), E.G. Kauffman (USA), W.J. Kennedy(UK), L.F. Kopaevich (Russia), M.A. Lamolda (Spain), G. Lopez(Spain), R. Martinez (Spain), T. Matsumoto (Japan), S. Monechi(Italy), F. Naji (Germany), H. Nestler (Germany), J. Obradovich(USA), E. Platon (Romania), J.M. Pons (Spain), I. Premoli-Silva(Italy), J. Rehánek (Czech Republic), K. von Salis (Switzerland), E.Seibertz (Germany), K.-A. Tröger (Germany), E. Urquhart (UK),C.J. Wood (UK).

Appendix II

Ammonites. A full account of the ammonite fauna of the sequenceis given by Kennedy in Gale et al. 1996.Nannofossils. The nannofossil sequence is described by Burnett inGale et al. 1996. The revised nomenclature of Burnett (1998) is usedhere. Planktonic foraminifera . Taxonomic notes on key species (Figure8) are as follows:

Rotalipora tehamensisMarianos & Zingula, 1966: this species(Figure 8: 7-9) was identified in Tunisia by Gonzales-Donoso inRobaszynski et al. 1994, pp. 432, 457, illustrated in their pl. 20, Fig.1, the stratigraphic range given in their text-fig. 36. This species dif-fers from R. ticinensis(Figure 8: 16–18) in having a higher trochos-pire, a narrow umbilicus with periumbilical flanges on all chambers.It differs from R. greenhornensisby the absence of curved sutures onthe spiral and umbilical faces.

Rotalipora gandolfii Luterbacher & Premoli-Silva, 1962:validly adopted by Robaszynski et al. 1979, pp. 81–84. This species(Figure 8: 4–6) evolved from R. appenninica(Figure 8: 1–3) by thedevelopment of a periumbilical flange and a more inflated umbilicalface to the last two chambers.

Rotalipora globotruncanoidesSigal, 1948 (Figure 8: 10–12): asynonymy was published by Gonzalez-Donoso in Robaszynski et

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al., 1994, p. 456. Caron herein, and in Gale et al., 1996 adopted asimilar interpretation.

The taxonomy of R. globotruncanoidesis complex, as sum-marised below.

- Sigal, 1948: two genera, RotaliporaBrotzen, 1942, and Thal-manninellagen. nov. recognised, as were two new species, Rotali-pora globotruncanoides Sigal, 1948, and Thalmanninella brotzeniSigal, 1948.

- Brönnimann & Brown, 1948: maintained ThalmanninellaandRotaliporaas separate genera on the basis of the presence of a char-acteristic cover plate in Thalmanninella.

- Bolli, 1957: treated Thalmanninellaas a junior synonym ofRotalipora, on the basis of the presence of sutural apertures in both.

- Sigal, 1958: Thalmanninellaalso regarded as a junior syn-onym of Rotalipora.

- Maslaskova, 1961-1963, Longoria, 1973: Rotalipora andThalmanninellakept separate on morphological criteria.

- Wonders, 1978: keeled Rotaliporinae divided into three gen-era, Rotalipora, Thalmanninella,and PseudothalmanninellaWon-ders, 1978.

- Robaszynski & Caron, 1979; Caron, 1985; Loeblich & Tap-pan, 1988: only Rotaliporarecognised.

- Gonzalez-Donoso in Robaszynski et al., 1994 returned to thedistinction of three phyletic groups within the rotaliporids, as recog-nised byWonders (1978), which he referred to Rotalipora, withThalmanninellaas a subgenus. He also (p. 456), referred to brotzeniSigal, 1948, as a “synonyme subjectif postérieur” of globotrun-canoidesbecause Sigal (1948) introduced the name globotrun-canoides on p. 100, and brotzenion p. 102 of the same work. Theterm “synonym subjectif postérieur” does not appear in the fourthedition of the International Code of Zoological Nomenclature, whilethe names globotruncanoidesand brotzeniare deemed to have beenpublished simultaneously under the Rules (Article 24.2.2). The actof listing brotzeniSigal, 1948, as a synonym of globotruncanoidesSigal, 1948, makes Gonzalez-Donoso (in Robaszynski et al., 1994,p. 456) “First Reviser” under the terms of Article 24.2.1 of the Code,and for those who believe brotzeniand globotruncanoidesto be syn-onymous, the specific name globotruncanoidestakes precedence.

- Robaszynski & Caron, 1995: recognised the genus Rotaliporaonly, accepted the act of Gonzalez-Donoso (1994), and affordedglobotruncanoidesprecedence over brotzeni. This is the positionadopted here.

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Michèle Caron is Professor ofMicropalaeontology at the Geologi-cal Institute of the University of Fri-bourg, Switzerland (doctorate in1967, Paris; habilitation in 1978,Fribourg). She teaches generalmicropalaeontology for the univer-sities of Fribourg, Berne, Neuchâteland Lausanne, as well as appliedmicropalaeontology. Her researchinterests are biostratigraphy, sys-tematics and the evolution of Creta-ceous planktonic foraminifera. Herwork is mainly applied to: the Creta-ceous of the Préalpes Médianes, theCretaceous of North Africa, andglobal palaeoceanography of theCenomanian-Turonian interval.

Jackie Lees (formerly Burnett)works in the NannoplanktonResearch Laboratory (Earth Sci-ences, UCL) as an HonoraryResearch Fellow. She received herdoctorate in 1988 from UCL, andhas been there ever since. She workson nannoplankton, her main areasof expertise being Cretaceous bios-tratigraphy and correlation, espe-cially integrated stratigraphyaround stage-boundaries, and LateCretaceous climate change. She isalso the Editor of the Journal ofNannoplankton Research.

Jim Kennedy is Professor of Nat-ural History at the University ofOxford, and Director of the OxfordUniversity Museum of Natural His-tory. His current areas of researchare in the taxonomy, evolution, bio-geography and biostratigraphy ofCretaceous ammonite faunas fromEurope, Central Asia, North, West,and South Africa, the AntarcticPeninsula, India, Pakistan, NorthAmerica, and Greenland.

Andy Gale was born on Late San-tonian Chalks in Canterbury, Kent.He took both his B.Sc. and Ph.D. atKing’s College, London. After apostdoctorate at Liverpool, hebecame a lecturer at City of LondonPolytechnic in 1985. In 1991 hemoved to Imperial College, and in1996 took up the Chair of Geologyat the University of Greenwich. Hisresearch interests encompass Creta-ceous and Tertiary sediments, inparticular bio- and chemostratigra-phy, sea-level change, Milankovitchcycles and palaeoenvironmentalreconstruction.