GENERAL OUTLINE OF THE BIOSTRATIGRAPHY OF CONIACIAN - SANTONIAN SEDIMENTS IN THE MID AND SOUTHERN ZAURALIE (TRANS-URALS, RUSSIA)

Edward O. Amon

Institute of Geology and Geochemistry of the Urals Branch of Russian Academy of Sciences. 620151 Ekaterinburg, Pochtovy per. 7. RUSSIA – e-mail: Amon@igg.uran.ru

The Zauralie (Trans-Urals), is a special geomorphologic territory, represented by a rather narrow band about 200-300 km wide along the complete east slope of the Urals mountain (Fig. 1).
The structure and composition of the Upper Cretaceous formations in western and eastern parts of Mid and Southern Zauralie differ (Fig. 2). A biostratigraphic subdivision of the Turonian – Campanian interval of the Upper Cretaceous sequence is shown in table:below.

Foraminifers play a most important role in Upper Cretaceous stratigraphy in the Zauralian territory, because macrofauna is rarely found in coresand is very rare, whereas foraminifers occur frequently and are rather well investigated and described. Based on foraminifers it is also possible to correlate the rocks not only of Western Siberia and Zauralie, but also of more remote areas of the Boreal Realm.

Fig. 1. Geographic location of Mid and Southern Zauralie (Trans-Urals).  1 recent borders of mountain territories,  2 line dividing Mid Zauralie from Southern Zauralie,  3 line dividing western part of Zauralie from eastern part,  4 directions of currents during Coniacian epoch.

Figure 2. General structure of the Turonian - Campanian interval of Upper Cretaceous sequence in Mid and Southern Zauralie.

CONIACIAN-SANTONIAN BIVALVES IN EUROPE

Annie V. Dhondt

Department of Palaeontology, Royal Belgian Institute of Natural Sciences, rue Vautierstraat 29, B – 1000 Brussels, Belgium
e mail: annie.dhondt@naturalsciences.be

Coniacian and Santonian are relatively short stages. In the temperate western, northern and eastern European strata they are represented by white chalks. The bivalve faunas do not change much between the two stages representing a period of stasis, even if the Upper Santonian faunas are more diverse than those of the Coniacian and Lower Santonian. At the Santonian-Campanian boundary we find Oxytoma (Hypoxytoma) tenuicostata (Roemer, 1841). In western Europe in the chalks the species is considered as lowermost Campanian whereas on the Russian platform and especially in western Siberia it already occurs in the uppermost Santonian (Amon 1979; Bobkova, 1979).
In southern Europe at the boundary between temperate and Tethyan regions in the Coniacian-Santonian time interval the faunas evolve more and are more diverse than in the temperate region s.s. – f.i. with the presence of more spondylids and of course rudists This is also connected with the presence of more strata formed by shallow marine environments.

According to Tröger (1989) the inoceramids of the Coniacian are subdivided in three different associations:
(1).the lower Coniacian is characterized by an assemblage zone with Inoceramus waltersdorfensis Andert, I. rotundatus Tröger non Fiege, Cremnoceramus deformis (Meek), Cr. schloenbachi (J. Böhm), Mytiloides incertus (Jimbo).
(2) the middle Coniacian is characterized by an assemblage zone with Inoceramus frechi Flegel, I. kleini G. Müller, I percostatus G. Müller, Volviceramus involutus (J.de C. Sowerby), Vo. koeneni (G. Müller). – and beginning of the Platyceramus mantelli sensu Barrois lineage.
(3) the upper Coniacian is characterized by an assemblage zone with Magadiceramus subquadratus (Schlüter), taxa of the Platyceramus mantelli sensu Barrois lineage, Continuing of the middle Coniacian Volviceramus taxa and in temperate regions the first taxa of the Sphenoceramus group.

According to Tröger (1989) the inoceramids of the Santonian can be subdivided in five assemblage zones but this much less clearly visible than in the Coniacian. Throughout the stage the presence is obvious of the Sphenoceramus group – it finishes in the lowermost Campanian. Platyceramus also continues throughout the Santonian into the Campanian – the Pl. cycloides (Wegner) lineage. Cladoceramus undulatoplicatus (F. Roemer) is only found in the lowermost Santonian as understood today. Taxa of the Cordiceramus group are typical for the middle and upper Santonian – occasionally reaching into the Campanian. In certain Tethyan regions Endocostea taxa already occur in the Santonian.

References
Amon, E. O., 1979. Issledovanie ismenchivosti predstavitelej vida Oxytoma tenuicostata (Roemer). Akademija nauk SSSR-Uralskij Nauchnij tsentr. Trudy instituta geologii u geokhimii 148: 71-74.
Bobkova, N. N., 1979. Oksitomy iz santon-kampanskikh otlozhenij Aktiybinskoj oblasti. in Granitsa Santona i Kampana na vostochno-evropejskoj platforme. Akademija nauk SSSR-Uralskij Nauchnij tsentr. Trudy instituta geologii u geokhimii 148: 66-70
Troeger, K. A., 1989. Problems of Upper Cretaceous Inoceramid Biostratigraphy and Paleobiogeography in Europe and Western Asia. in: J. Wiedmann Editor: Cretaceous of the Western Tethys. Proceedings of the 3rd International Cretaceous Symposium Tübingen 1987. E. Schweizerbart’sche Verlagsbuchhandlung (Nägele u. Obermiller) Stuttgart : 911- 930.

SOME CONIACIAN-SANTONIAN BOUNDARY SECTIONS IN THE USA

Andy Gale¹ and Jake Hancock²

¹University of Greenwich, School of Earth Science, Pembroke, Medway Towns Campus, Chatham Maritime BE4 4AW, U.K. e mail: <A.S.Gale@gre.ac.uk>
²Department of Earth Science & Engineering, Imperial College of Science, Technology & Medicine, Prince Consort Road, London SW7 2BP, U.K.

One of the three candidates for the boundary stratotype section at the Brussels symposium was Ten Mile Creek, Dallas, Texas. We have revisited this creek since the Brussels meeting and have to report that it would not make a satisfactory standard. There are geological imperfections in the section of the Austin Chalk: exposures are discontinuous in the banks of the river; only a few metres below the lowest Texanites found (ammonites are scarce), there is a level of erosional channels tens of metres across which could make for uncertainties in the detailed succession. But the main weakness is that the land alongside the critical part of the succession is prime building land in an expanding town.
Other sections that will be considered briefly include: 1. the Vinson Chalk near Austin, Texas, probably the origin of Romer's types of Inoceramus undulatoplicatus; 2. the Middle Shale member of the Niobrara Group in Pueblo State Park, Colorado; 3. The Smoky Hill Chalk Member in western Kansas and Nebraska.

CONIACIAN/SANTONIAN BOUNDARY IN RIU DE CARREU VALLEY AND PRATS DE CARREU, SOUTH-CENTRAL PYRENEES (N SPAIN)

Jaume Gallemí¹, Gregorio López^2,3, Ricardo Martínez³, Ramón Mercedes³ & Jose Maria Pons³

¹ Museu de Geologia (Museu de Cienciès Naturals de la Ciutadella). Parc de la Ciutadella s/n 08003-Barcelona, Spain. Jaume.Gallemi@uab.es
² Centre de Sédimentologie-Paléontologie. Case 67. 3, place Victor Hugo, 13331 Marseille cedex 03, France. gregori.lopez@blues.uab.es
³ Departament de Geologia. Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Bellaterra (Barcelona), Spain. Ricard.Martinez@uab.es, JosepMaria.Pons@uab.es

A conspicuous level containing Platyceramus undulatoplicatus (Roemer) occurs in several stratigraphic profiles measured and sampled in a 15 km wide area along Riu de Carreu valley and Prats de Carreu. This is the index species for the Coniacian-Santonian boundary following the criterion suggested for the definition of the Coniacian-Santonian boundary by the Santonian working group (Lamolda & Hancock, 1996). Its presence, not only allows the identification in this area of the Coniacian-Santonian boundary, but also facilitates the re-examination of previous biostratigraphic framework. It becomes also evident that the presence of Platyceramus undulatoplicatus is relatively facies independent, since it occurs from the calcareous platform of the western part of the area to the talus marls of the eastern one.
The area is located at the northern flank of the Sant Corneli Anticline, a southward verging South Pyrenean thrust propagation fold, and the outcrops, of well developed platform and basin facies, range from the Coniacian to the Santonian and are extremely well exposed.
Stratigraphic units of the area were formally named by Gallemí et al. (1982). However, other authors have been inconsistently using informal names (Gili et al., 1996, Vicens et al., 1998).
The biostratigraphic survey on these platform-basin outcrops is based mainly on inoceramids, rudists, ammonites, echinoids, brachiopods and planktonic foraminifera. Early biostratigraphic framework has been developed by Pons (1977), Martínez (1982), Gallemí et al. (1983), López (1986), Gómez-Garrido (1989), Gallemí (1994) and Muñoz (1995). Vicens et al. (1998) correlated, both stratigraphically and sequentially, the transit between basin and platform sequences in the western part of the area.
High-resolution biostratigraphic framework on inoceramid-ammonite biozones is being currently developed to check accurate relationships between Platyceramus undulatoplicatus and other fossils record, especially that of Texanites species. The lowermost Santonian is precisely established by means of the very abundant and conspicuous Platyceramus undulatoplicatus (Roemer). This index inoceramid species co-occurs mainly with other bivalves, echinoids and sponges. Other inoceramid species showing divergent ribs, as Cordiceramus cordiinitialis ickernensis (Seitz), are also reported in the Lower Santonian of the studied area.
Upper Coniacian inoceramids are characterised by Magadiceramus species, as Magadiceramus subquadratus subquadratus (Schlüter) and Magadiceramus soukupi (Macáck); they overlie or co-occur with Protexanites bourgeoisi (d’Orbigny), ammonite marker for the upper part of the Upper Coniacian. Rudist faunas co-occur just below the Platyceramus undulatoplicatus beds.

References
Gallemí, J. 1994. Los yacimientos con equínidos del Cretácico Superior del Prepirineo de la provincia de Lleida. Tesis Doctoral microfilmada. Publicacions de la Universitat Autonoma de Barcelona, 429 p.
Gallemí, J., Martínez, R. & Pons, J.M. 1982. Unidades del Cretácico superior en los alrededores de Sant Corneli (Provincia de Lleida). Cuadernos de Geología Ibérica, 8: 935-948.
Gallemí, J., Martínez, R. & Pons, J.M. 1983. Coniacian-Maastrichtian of the Tremp Area (South Central Pyrenees). Newsletter on Stratigraphy, 12: 1-17.
Gili, E., Obrador, A., Vicens, E., Skelton, P. & López, G. 1996. Las formaciones de rudistas de la plataforma de Sant Corneli (Cretácico superior, unidad central surpirenaica). Revista Española de Paleontología, Nº extraordinario: 172-181.
Gómez-Garrido, A. 1998. Bioestratigrafía (foraminíferos planctónicos) del Cretácico superior del Surpirineo Central (España). Revista Española de Micropaleontología, 21 (1): 145-178.
Lamolda, M.A. & Hancock, J.M. 1996. The Santonian Stage and substages. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre, 66-supp.: 95-102.
López, G. 1986. Inocerámidos del Cretácico superior de los alrededores de St. Corneli (prov. de Lleida). Publicaciones de Geología. Universitat Autònoma de Barcelona, 22: 1-123.
Martínez, R. 1982. Ammonoideos cretácicos del Prepirineo de la provincia de Lleida. Publicaciones de Geología. Universidad Autónoma de Barcelona, 17: 1-197.
Muñoz, J. 1995. Estudio paleontológico y bioestratigráfico de los braquiópodos del Cretácico superior del Sudpirineo catalán. Tesis Doctoral microfilmada. Publicacions de la Universitat Autonoma de Barcelona, 413 p.
Pons, J.M. 1977. Estudio estratigráfico y paleontológico de los yacimientos de rudístidos del Cretácico superior del Prepirineo de la provincia de Lérida. Publicaciones de Geología. Universidad Autónoma de Barcelona, 3: 1-105.
Vicens, E., López, G. & Obrador, A. 1998. Facies succession, biostratigraphy and rudist faunas of Coniacian to Santonian platform deposits in the Sant Corneli anticline (southern Central Pyrenees). Geobios, M.S. n° 22.: 403-427.

SENONIAN ASYMMETRICAL RHYNCHONELLID BRACHIOPODS

Daniele Gaspard

Université de Paris-Sud, Département des Sciences de la Terre, FRE CNRS-UPS 2566, Bât. 509, F-91405 ORSAY Cedex. e mail: gaspard@geol.u-psud.fr

Among Cretaceous Rhynchonellida various representatives of the genus Cyclothyris Owen (1962) often show a peculiarity concerning the anterior margin, they are asymmetrical (right or left–tilted). These rhynchonellids are diversely represented in the Senonian of Europe and North Africa (Gaspard, 1983). The part of genetic implications of this asymmetrical anterior margin is taken into account without neglecting the environmental impact (Gaspard, 1991).
The collections observed are among others: the collections of palaeontology de l’ENSM de Paris (Lyon); samplings of MM. Babinot and Tronchetti, Université de Marseille; samplings of M. Bilotte, Université de Toulouse; Coll. Arnaud, Université Paris 6, Jussieu.
The name of Rh. difformis Val. in Lmk, used for Cenomanian specimens is also wrongly conferred to specimens from the Coniacian-Santonian of the Pyrenean region (Bois-du-Vicomte, Fondfroide, Sougraigne, Rennes-les-Bains, Boutenac (calcaires à Echinides) and from the Santonian of Southeast France: le Beausset, la Cadière, Martigues (Gaspard 1991). This species name is debatable, first of all, no representatives of the species have been recorded between the Cenomanian and the Coniacian and secondly the general the shell shape is not comparable for specimens in both cases. The Senonian specimens are more gibbous, with a more curved ventral umbo. Coquand (1879) introduced a new asymmetrical species: Rh. Claudicans, from North Africa, but did not provide illustration.
Considering the external and internal (through transverse serial sections) characteristics of the specimens it appears that the Senonian specimens are completely different from Cyclothyris difformis and also from the asymmetrical C. vesicularis and for most part from C. globata (Arnaud) from the Campanian. In other respect the material from the Pyrenean region and S.E. France appears heterogeneous. Part of the specimens from Rennes-les-Bains and specimens from the Coniacian of Montsec (Pyrenees, Spain), with a globular shell ornamented by thinner costellae present similarities with some specimens of C. globata and with the material from the province of Lleida presented as Rh.claudicans by Muñoz (1985). Other specimens are relatively less globular, wider with strong costae, in Rennes-les-Bains, Sougraignes, they can be compared with those from the Santonian at le Beausset (calcaire à Rudistes) and Upper Santonian (3rd layer with Hippurites) at le Castellet and Martigues. In this last locality under the same former species name, several kinds of shells are observed, some being compared with C. eudesi (Coquand) (species with mainly uniplicate anterior margin). But sometimes the shifting of the anterior margin occasionally observed, in this species (cf. Cognac, France), is found in Martigues, with specimens really asymmetrical. The species assessment of these members of the genus Cyclothyris is discussed to find another species name for the stronger costellate specimens.

References
Coquand, H. 1879. Etudes supplémentaires sur la paléontologie Algérienne faisant suite à la description géologique et paléontologique de la région sud de la province de Constantine. Bull. Acad. Hippone.
Gaspard, D. 1983.- Distribution des Brachiopodes du Coniacien au Maastrichtien en France et pays limitrophes. Géologie Méditerranéenne. 10, 229-238.
Gaspard, D. 1991.- Les cas de non-symétrie chez les rhynchonelles, quelle(s) signification(s). Géobios. 13, 33-44.
Muñoz, J. 1985.- Braquiópodos del Cretácico Superior de los alrededores de St. Corneli (Prov. Lleida, Tesina) Universitàt Autonoma de Barcelona, Geologia, 21, 124.
Owen E.F., 1962.- The brachiopod genus Cyclothyris. Bull. Brit. Mus (Nat. Hist.), Geology, 7,2, 39-63.

CONIACIAN-SANTONIAN DEPOSITIONAL SEQUENCES IN THE BASCO-CANTABRIAN BASIN (N. SPAIN)

Kai-Uwe Gräfe

Geosciences Department; University Bremen; P.O. Box 33 04 40; D-28334 Bremen
e-mail: ugraefe@micropal.uni-bremen.de

In the Basco-Cantabrian Basin, Coniacian to Santonian sediments were deposited in a 5 myr. long transgressive-regressive cycle (the Losa sequence). The Losa sequence is composed of three short-term depositional sequences called UC9/10, UC10/11, and UC11/12. The base of the Losa Sequence is formed of a 300 m thick lowstand systems tract of sequence UC9/10. These shallow-marine carbonates of the Ribera Alta Fm. pinch out towards the proximal or Castillian ramp, which is emergent in this time. This emersion is recorded in a weak angular unconformity on the Castillian ramp. More basinward, the Ribera Alta Fm. interfingers with calciturbidites.
During the Early Coniacian (Tridorsatum Zone) a major marine transgression flooded the Castillian Ramp from the north. Argillaceous limestones and claystones rich in ammonites and benthic foraminifers (Nidaguila Fm.) were deposited first in a short-term depositional sequence (UC9/UC10). After a second strong transgressive pulse sedimentation continued in a depositional sequence that covers the rest of the Coniacian. The maximum flooding surface of this sequence is dated as lying in the Margae Zone. In the marginal marine facies belt, retrograde oyster facies-belts and calcarenites characterizes the transgressive systems tract (Muñecas and Hortezuelas Formations). Micritic lagoonal limestones form the prograding highstand systems tract on the Castillian ramp.
This Coniacian depositional sequence is terminated by sequence boundary UC11 which is expressed as subaerial exposure surface on the inner ramp. The Coniacian-Santonian boundary (the boundary between Lenticeratiformis and Gallicus Zones) is recognized before this sequence boundary in the highstand systems tract of depositional sequence UC10/11. Deeper-marine deposits of the Coniacian are formed of distal calciturbidites and of planktic foraminiferal marl-limestone alternations (Zadorra and Olazagutia Formations). The distal Coniacian calciturbidites exhibit features of low-density slope apron turbidites.
The Early to Late Santonian is dominated by depositional sequence UC11/UC12 composed of a thin lowstand systems tract, and equally thick transgressive and highstand systems tracts. In the Early Santonian the major flooding of the Castillian ramp occurred from North to South with the deposition of planktic foraminiferal marlstones (Olazagutia Formation), micritic ammonite-rich limestones and marls (Valle de Losas Fm.) and open-marine limestones of the Nocedo de Burgos Formation. Lagoonal biomicrites (Sierra de Utiel Fm.) and fine-grained bioclastic calcarenites (Hontoria del Pinar Fm.) compose the transgressive systems tract in the marginal domains.
The maximum-flooding event of sequence UC11/12 is dated from the Hourcqi Zone. At this time, the Iberian strait was wide-open but deepening was moderate. Water depth was lesser than in the Early Turonian as is evident by the absence of planktic foraminifers in sections in the Central Castillian Ramp (for example Picofrentes). The accommodation space of the Iberian Strait was filled during the late Santonian highstand systems tract. Shallow-marine facies belts prograde to the north. The northward progradation ends with a subaerial exposure and karstification of the whole proximal ramp, which is evident in many sections.

SEAFORD HEAD, A PROPOSED INTERNATIONAL STRATOTYPE FOR THE SANTONIAN-CAMPANIAN BOUNDARY

Matthew J. Hampton¹, Haydon W. Bailey¹, Liam T. Gallagher¹, Rory N. Mortimore² and Christopher J. Wood³

¹ Network Stratigraphic Consulting Ltd. Unit 60, The Enterprise Centre, Cranborne Road, Potters Bar, Hertfordshire, UK, EN6 3DQ
² Geology Division, School of the Environment, University of Brighton, Brighton, UK, BN2 4GJ.
e mail: rory.mortimore@btinternet.com
³ Scops Geological Services Limited, 20 Temple Road, Croydon, UK, CR0 1HT

Seaford Head has been suggested as a possible international stratotype section for the Coniacian – Santonian and Santonian – Campanian boundaries (Birkelund et al., 1984). Hancock and Gale (1996) have proposed alternative sections. This paper will present the results of a detailed study of the nannofossil and foraminiferid biostratigraphy integrated with the macrofossil distribution and lithostratigraphy of Seaford Head for the first time. Detailed descriptions of access to and exposures present in the Seaford Head cliffs are given in Mortimore (1997) and Mortimore, Wood and Gallois (2001).

Location and accessibility of the section
Upper Cretaceous Chalk at Seaford Head is brought to the surface on an anticline with dips of up to 10º north. The relatively gentle dip provides convenient sections through all the Chalk from the Turonian – Coniacian boundary to the Gonioteuthis quadrata Zone in the Early Campanian. The site is accessed from the west across coast protection works and on to a Chalk wave-cut platform variably covered in beach material (depending on storm directions).

Lithostratigraphy and macrofossil biostratigraphy
Both a broad lithostratigraphic framework of Chalk formations and members and a detailed marker bed lithostratigraphy have been developed for the Chalk at Seaford Head. These formations and marker beds are not restricted to Seaford Head but are used widely throughout the Anglo-Paris Basin (Mortimore & Pomerol, 1987; Bristow et al., 1997). Seaford Head is the type locality for the Seaford and Newhaven Chalk formations, their basal boundary markers and many of the lithological marker beds.
The Coniacian – Santonian and Santonian – Campanian boundaries are not coincident with the major lithological boundaries, falling instead within the Seaford and Newhaven Chalk formations respectively. The key marker beds at the Coniacian – Santonian boundary are the Michel Dean, Baily’s Hill and Flat Hill flint bands. Marker beds at the Santonian – Campanian boundary include the Friars Bay Marls, Friars Bay Flints, Black Rock Marl, the Rottingdean and Roedean marls and the Old Nore Marl and Flints. The Macrofossil Zonation follows that traditionally used in European chalk facies in the absence of index ammonites and is described in Mortimore et al. (2001).

Nannofossil zonation
The nannofossil stratigraphy defined in this study is based on the scheme defined by Burnett (1998) for the Boreal Late Cretaceous. It is refined by Fritsen et al. (2000) utilising data from the Central Graben chalks of the North Sea and outcrop material from the U.K. and Germany.
Although the zonal markers cited by Burnett (1998) were identified in this study and therefore the overall zonal framework holds, many of the species criteria used for subzonal division were not identified. In addition the calibration between some of the nannofossil events and the chronostratigraphy presented by Burnett (1998) is refined herein and correlated with the lithostratigraphy for the first time.
The Santonian part of the Seaford Chalk Formation analysed in this study contains nannofossil Zones UC11 based on the occurrence of Lithastrinus septenarius UC12 between the LO of L. septenarius at SFH90 and the FO of Arkhangelskiella cymbiformis at SFH73. The Newhaven Chalk Formation contains nannofossil Zone UC13 based on the FO of A. cymbiformis and Zone UC14, based on the inception of Broinsonia parca parca.

Foraminiferid zonation
The foraminiferid stratigraphy defined in this study is effectively a subdivision (subzonation) of three of the zones defined by Hart et al. (1989) on the basis of the benthic foraminiferids recorded. This study concentrates on the Santonian to mid Campanian (quadrata Zone) succession of the Seaford Head section only, however reference is also made to key sections elsewhere in southern England. The poster version of this report shows the position of the zones and marker beds in relation to the lithostratigraphy. Planktic foraminiferids occur throughout the section, but in insufficient numbers and too low a diversity to allow a zonal scheme to be developed. Distribution of planktic forms, particularly local levels of abundance, is discussed.

References
Birkelund, T., Hancock, J. M., Hart, M. B., Rawson, P. F., Remane, J., Robaszynski, F., Schmid, F. and Surlyk, F. 1984. Cretaceous stage boundaries - Proposals. Bulletin of the geological Society of Denmark, 33, 3-20.
Bristow, C. R., Mortimore, R. N. and Wood, C. J. 1997. Lithostratigraphy for mapping the Chalk of southern England. Proceedings of the Geologists’ Association, 108, 293-315.
Burnett, J. A. 1998. Chapter 6. Upper Cretaceous. In Calcareous Nannofossil Biostratigraphy (ed P. R. Bown), Chapman and Hall, London, pp. 132-99.
Fritsen, A., Bailey, H. W., Galagher, L., Hampton, H. et al. 2000. A joint Chalk Stratigraphic Framework. JCR Symposium, Brighton, 21 – 24 March 2000, 1-2.
Hart, M. B., Bailey, H. W., Crittenden, S., Fletcher, B. N., Price, R. J. and Swiecicki, A. 1989. Chapter 7. Cretaceous. In Stratigraphical Atlas of Fossil Foraminifera, 2nd edn, (eds D.G. Jenkins and J.W. Murray), Ellis Horwood Ltd., Chichester, for the British Micropalaeontological Society, pp. 273-371.
Hancock, J. M. and Gale, A. S. 1996. The Campanian Stage. Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre, 66-supp., 103-109.
Mortimore, R. N. 1997. The Chalk of Sussex and Kent. Geologists’ Association Guide No. 57, The Geologists’ Association.
Mortimore, R. N. and Pomerol, B. 1987. Correlation of the Upper Cretaceous White Chalk (Turonian to Campanian) in the Anglo-Paris Basin. Proceedings of the Geologists’ Association, 98, 97-143.
Mortimore, R. N., Wood, C. J. and Gallois, R. W. 2001. British Upper Cretaceous Stratigraphy. Geological Conservation Review Series, No. 23. Joint Nature Conservation Committee, Peterborough. 558pp.

BASE OF THE SANTONIAN - AN OVERVIEW

Jake Hancock

Department of Earth Science & Engineering, Imperial College of Science, Technology & Medicine, Prince Consort Road, London, SW7 2BP, U.K.

At the Copenhagen meeting in 1983 only two possible boundary levels to mark the base of the Santonian were considered: the lowest Texanites (Texanites) and the lowest Inoceramus (Cladoceramus) undulatoplicatus Romer. By the time of the Brussels symposium in 1995 it had become known that the first Texanites occurs distinctly below the lowest C. undulatoplicatus in central and north Texas and in northern Spain. The Brussels meeting also considered stratigraphical data on both planktic and benthic foraminifera and on nannotossils (Lamolda & Hancock 1996). Both at Brussels and in a subsequent postal vote there was strong support for the use of the lowest Cladoceramus undulatoplicatus as the primary marker. This species is easy to recognise even when incomplete and is known from Texas, Colorado, Kansas and California in the USA; from much of Europe, including Spain, France, England, Germany and Austria, but possibly not in Poland and the Ukraine; in the former USSR; in the Kopet-Dagh on the border between Turkmenia and Iran. But in the Southern Hemisphere it is much less prominent, being recorded from Madagascar and South Africa (Dondt 1992), but not from New Zealand (Crampton 1996). Even in areas where the species is well known, its appearance can be sudden in great numbers, e.g. southern England: this suggests an immigration event. The inoceramid zonation around the Coniacian-Santonian boundary still needs investigation as has been shown by Tröger (1989).
Secondary markers are needed, particularly amongst micro- and/or nannofossils because there are so many successions which lack macro-fossils, or in which they are scarce, e.g. oceanic sediments. At present the nanno-fossils are not encouraging. Amongst the foraminifera, the planktics are all too often lost by post-depositional solution, particularly in chalks (Curry 1982). Benthic foraminifera may well be better and any selection of a boundary stratotype should contain this group.
There is also a need for non-fossil markers, such as Sr isotope data.

References
Crampton, J. S. 1996. Inoceramid bivalves from the Late Cretaceous of New Zealand. Institute of Geological and Nuclear Sciences Monograph 14, 188 pp.
Curry, D. 1982. Differential preservation of foraminiferids in the English Upper Cretaceous consequential observations. In Banner, F.T & Lord, A.R. (eds) Aspects of Micropalaeontology, 240-261. London, George Allen & Unwin.
Dhondt, A. V. 1992. Cretaceous inoceramid biogeography: a review. Palaeogeography, Palacoclimatology, Palaeoecology, 92, 217-232.
Lamolda, M. A. & Hancock, J. M. 1996. The Santonian Stage and substages. Bulletin de l'lnstitut Royal des Sciences Naturelles de Belgique: Sciences de la Terre, v.66-Supp, 95-102.
Tröger, K.-A. 1989. Problems of Upper Cretaceous inoceramid biostratigraphy and paleobiogeography in Europe and western Asia. In Wiedmann, J. (ed.) Cretaceous of the Western Tethys (Proceedings of the 3rd International Cretaceous Symposium, Tübingen 1987), 911-930. Stuttgart, Schweizerbart'sche.

THE CONIACIAN-SANTONIAN BOUNDARY IN MANGYSHLAK PENINSULA AND PERI-CASPIAN BASIN (WEST KAZAKHSTAN). A MULTISTRATIGRAPHIC IMPLICATION

Ludmila F. Kopaevich¹ and Vladimir N. Beniamovskii<sup>2

1</sup>Geological Faculty, Moscow State University, 119899 Moscow, Russia. e mail: lkopaev@geol.msu.ru
²Geological Institute, Russian Academy of Sciences, 109017 Moscow, Russia. e mail: ben@geo.tv-sign.ru

Western Kazakhstan represented the marginal, south-easternmost part of the European Palaeobiogeographical province stretching from the Atlantic coasts in the west to the western tips of Central Asia during Cretaceous. It is in the Mangyshlak Mountains that the most extensive exposures are accessible for direct studies. The range of the Mangyshlak mountains represents a quite regular anticline-like structure, particularly well traceable in its central and western parts. The whole Mangyshlak area was the site of marine sedimentation with temporary emersion and erosion during Jurassic up to the late Paleogene times. Mid-Cretaceous was marked in Mangyshlak and Peri-Caspian basin by acceleration of the Cretaceous transgression with the accompanying facies change from terrigenous clastics to carbonates and Coniacian-Santonian interval is represented by chalks and chalky marls. This sequence contains many small hiatuses. Shakh-Bogota is one of the studied sections with almost complete Upper Turonian-Lower Santonian successions. Thickness of Coniacian-Lower Santonian interval is 65 m. The Coniacian-Santonian boundary was defined thanks to LO of Volviceramus involutus (Sowerby) and FO of the Cladoceramus undulatoplicatus (Roemer) inoceramid species. Rare Micraster rogalae Nowak appears at the topmost Coniacian-lowermost Santonian horizon together with common Micraster coranginum (Leske). Benthic Foraminifera predominate in the Upper Coniacian-Lower Santonian deposits of the Shakh-Bogota section. A few evolutionary events of the phylogenetic development of Stensioeina, Gavelinella and Neoflabellina can be recognized around the Coniacian-Santonian boundary. The following bioevents were detected there: (1) abundant Stensioeina granulata granulata and simultaneous FO Gavelinella vombensis and G. costulata which coincide with early-middle Coniacian boundary; (2) FO G. thalmanni and Neoflabellina suturalis; (3) LO G. thalmanni; (4) FO Stensioeina exculpta exculpta, Gavelinella umbilicatula together with LO of Volviceramus involutus; (5) FO Stensioeina granulata perfecta which coincide with FO Cladoceramus undulatoplicatus; (6) FO Stensioeina granulata incondita, Stensioeina exculpta gracilis and Gavelinella stelligera in the middle of Santonian above first C. undulatoplicatus. Planktonic Foraminifera shows tendency to increase of convexity of ventral side. Upper Coniacian – Lower Santonian interval contains Dicarinella spp. with convex umbilical side from Dicarinella primitiva – D. concavata – D. asymetrica lineage. Just above the first Cladoceramus undulatoplicatus, D. asymetrica appears. However marginotruncanids forms with flattened spiral side are continuous to occur. Among heterohelicids representatives of Heterohelix globulosa appear together with first C. undulatoplicatus. This species has the last chambers which increase very rapidly in size.
Detailed analysis of published foraminiferal records from Coniacian-Santonian boundary successions at other localities showed the similarity of Mangyshlak - Peri-Caspian data with the North Europe and Mediterranean Europe also. Unfortunately the foraminiferal marker – Sigalia carpatica – is absent at the Caspian area.

CALCAREOUS NANNOFOSSIL MARKERS OF THE CONIACIAN/SANTONIAN BOUNDARY INTERVAL – A REVIEW.

Mihaela C. Melinte¹ and Marcos A. Lamolda²

¹National Institute of Marine Geology and Geoecology, Dimitrie Onciul 23-25, 78318 Bucharest, Romania.
e mail: melinte@geoecomar.ro
²Facultad de Ciencias-UPV, 48940 Lejona, España. e mail: gpplapam@lg.ehu.es

The calcareous nannofossils proved a high utility in defining the stages/substages of the Upper Cretaceous, interval showing an acme of their diversity and abundance. One of the first zonations, based on researchs of the Upper Cretaceous stratotypes, was published by Manivit (1971). This author, studying the historical stratotype of the Santonian from Saintes (France), identified at the base of this stage the FO of the nannofossil Kamptnerius magnificus. Later, this species was frequently reported from the Turonian. Sissingh (1977), investigating Upper Cretaceous tethyan sections (from south-west Europe and northern Africa), pointed out the base of the Santonian on the FO of Reinhardtites anthophorus (his CC15 Nannozone, recalibrated by Burnett, 1996). In the zonation of Perch-Nielsen (1985), also recalibrated by Burnett (1996), the Coniacian/Santonian Boundary falls between the FO of Reinhardtites anthophorus and the FO of Lucianorhabdus cayeuxii. In northern Spain (western Alava), the Coniacian/Santonian Boundary is situated, after Gorostidi et al., 1990, within the Micula concava Zone. The boundary is marked by a high abundance of the index species of the nannozone.
The appearance of the nannofossils Lucianorhabdus cayeuxii species A (sensu Wagreich, 1992) is considered, by the above mentioned author, a proxy of the Coniacian/Santonian Boundary in the Gosau Group from Austria. An increasing frequency of the holococcoliths, together with the radiation of the Lucianorhabdus was observed within the Coniacian/Santonian Boundary Interval from the West Carpathians (Svabenicka, 1992).
In the East and South Carpathians (Romania) the Coniacian/Santonian Boundary Interval is placed between the FO of the nannofossil Micula concava and the LO of Lithastrinus septenarius. The boundary is marked by a high frequency of Micula and Nannoconus species. In the integrated stratigraphical scheme of Bralower et al. (1995) the Coniacian/Santonian Boundary Interval is situated between the FO of Micula staurophora and the FO of Lucianorhabdus cayeuxii. Burnett (1998) identified, mainly based on the study of high-latitude successions, several nanno-events around the Coniacian/Santonian Boundary Interval, as follows: successive Upper Coniacian FOs of Lucianorhabdus cayeuxii, Cribrocorona gallica, Prediscosphaera grandis and Micula concava, followed by the FO of Amphizygus minimus as well as of Rucinolithus hayi, in the Lower Santonian.
The study of the calcareous nannofossils from Olazagutia (N Spain), section selected as one of the possible stratotypes of the Coniacian/Santonian Boundary, pointed out the successive appearances, within the Upper Coniacian, of the nannofossils Lithastrinus grillii, Lucianorhabdus cayeuxii and Calculites obscurus (Lamolda et al., 1999; Melinte & Lamolda, 2002). The LO of Lithastrinus septenarius was recorded as a Lower Santonian nanno-event.
As concerning the character of the calcareous nannofloras recorded in the Coniacian/Santonian Boundary Interval, this is mainly a cosmopolitan one. However, a small group of nannofossil taxa seems to be more related to high-latitudes (e.g. Thiersteinia ecclesiastica, Kamptnerius magnificus) or to the low-middle ones (the genera Nannoconus and Micula).

References
Bralower, T.J., Leckie, R.M., Sliter, W.V. and Thierstein, H.R. 1995: An integrated Cretaceous microfossil biostratigraphy. – In Berggren et al. (Eds): Geochronology, time scales and global stratigraphic correlation. – SEPM Special Publication, 54, 65-79.
Burnett, J. A. 1996: Nannofossils and Upper Cretaceous (sub-) stage boundaries – State of the art. - Journ. Nannoplankton Res., 18, 1, 23-32.
Burnett, J. A. 1998: Upper Cretaceous. – In: Bown, P. R. (ed.): Calcareous Nannofossil Biostratigraphy. – British Micropalaeont. Soc. Publ. Series: 132-199. Chapman & Hall Ltd/Kluwer Academic Press.
Gorostidi, A., Flores, J. A. and Lamolda, M. A. 1990: Aspectos tafonómicos y paleoecológicos de la nannoflora calcárea del Cretácico superior de Álava Occidental. – In: Civis, J. & Flores J. A. (eds): Actas de Paleontología, 68: 159-171.
Lamolda, M. A., Melinte, M. C. and Peryt, D. 1999: Datos micropaleontológicos preliminares sobre el límite Coniaciense/Santoniense en Olazagutía (Navarra, España). – Rev. Esp. Micropaleont., 31 (3): 337-345.
Manivit, H. 1971: Nannofossiles calcaires du Crétacé français (Aptien-Maastrichtien). Essai de Biozonation appuyée sur les stratotypes. - Thèse de Doctorat, Université de Paris, 387pp.
Melinte, M. C. and Lamolda, M. A. 2002: Calcareous nannofossils around the Coniacian/Santonian Boundary Interval in the Olazagutia section (N. Spain). In Wagreich, M. (Ed): Proceedings of the 6th Cretaceous Symposium, Austrian Academy of Science (in press).
Perch-Nielsen, K. 1985: Mesozoic calcareous nannofossils. – In: Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds): Plankton Stratigraphy: 329-426, Cambridge (Cambridge University Press).
Sissingh, W., 1977: Biostratigraphy of Cretaceous calcareous nannoplankton. - Geol. Mijnb., 56: 37-65.
Svábenická, L. 1992: Upper Cretaceous Nannofossils from the Klement Formation (Flysch Belt of the West Carpathians, Czechoslovakia). – Knihovnicka ZPN, 14a/1: 189-205.
Wagreich, M., 1992: Correlation of Late Cretaceous calcareous nannofossil zones with ammonites and planktic foraminifera: the Austrian Gosau sections. – Cretaceous Res., 15: 505-516.

OXYGEN AND CARBON STABLE ISOTOPES FROM ZUMAYA, N SPAIN

Christopher R. C. Paul¹ and Marcos A. Lamolda²

¹ Department of Earth Sciencies, Liverpool University, Brownlow St., Liverpool L69 3BX, England.
e mail: crcp@liverpool.ac.uk
² Facultad de Ciencias-UPV, 48940 Lejona, España. e mail: gpplapam@lg.ehu.es

Methods
The section at Zumaya exposes a thick, continuous sequence through almost the entire Maastrichtian, across the Cretaceous/Tertiary boundary (KTB) and well into the Danian, in sparsely fossiliferous marly sediments which are sometimes obviously rhythmic and sometimes not, and which contain numerous thin distal turbidite sand beds. We logged the section in the bays west of St Telmo’s Point from Wiedmann’s bed 2 up the top of bed 11 (Wiedmann, 1988 = from low in Member I to the top of Member IV of Ward et al., 1991; Ward & Kennedy, 1993; Marshall & Ward, 1996). Samples for isotope, microfossil and nannofossil analyses were taken from the top of Wiedmann’s bed 5 well into bed 10. This interval extends from approximately 45 m below to 40 m above the Lower - Upper Maastrichtian boundary as defined by the first appearance (FAD) of genuine Abathomphalus mayaroensis (Bolli), which we place just below the boundary between Wiedmann’s units 7 and 8 (107.25 m in our section). This is considerably higher than in many published sections, including Wiedmann (1988). Stable isotope samples were taken at approximately 1-2 m intervals; micro- and nanno-fossil samples approximately every 4-5 m. All samples were located on the same log, so the order of isotope, microfossil and nannofossil events is unambiguous.
At Sopelana, we logged a section to the northeast of the well-known KTB section above the swimming pool in the main bay (see fig. 2 in Lamolda et al., 1983). This section extends across the Lower - Upper Maastrichtian boundary and we collected ten samples for isotope analysis through the whole of Wiedmann’s bed 7.
In the laboratory, samples were dried overnight in an oven at 60 degrees celsius before any further preparation. Approximately 3 mg samples of powder were used to determine stable isotope values of carbon and oxygen in the Liverpool University Stable Isotope Laboratory using standard techniques.

Results
A) Zumaya
The carbon isotope curve at Zumaya rises to a peak of about +2.4 ‰ low in unit 6, then follows a broad trough down to values around +1.5 ‰ through unit 7, rising to a second peak of about +2.1 ‰ high in unit 8, and finally a second decline through units 9 and 10. The highest samples in unit 10 yield widely fluctuating values between about +0.9 and +1.6 ‰. Superimposed on these broad trends are two distinctly more negative values within unit 7. These values occurred in pilot samples taken in 1997, so in 1998 we sampled more closely through the intervals immediately surrounding these apparent excursions. However, the two values remain as isolated points on the curve. Immediately adjacent samples taken in 1998 are still close to the general curve and do not support the idea that genuine excursions occur. It seems more likely that these are two rogue values which is always a risk when using bulk sediment samples.
The oxygen curve at Zumaya shows very little overall trend, but values do rise to an initial peak of -2.7 ‰ low in unit 6 and there is some evidence of shifts across unit boundaries that may well reflect diagenesis. Values start around the average of about -3.5 ‰ in unit 5. They jump to less negative values in unit 6 and then drop back again to the average value in unit 7. Within unit 7 there are three low values, two of which correspond to the two samples which yielded the very low values for carbon. Values remain around the average through units 8 and 9, although showing less variation than in unit 7, and finally jump again to slightly less negative values in unit 10. Despite several quite sharp changes in value across unit boundaries, there is no consistent relationship between lithology and oxygen values. Limestone-rich units (6, 8 and 9) do not have consistently different values compared to limestone-poor units (7 and 10).

B) Sopelana
At Sopelana we took 10 samples through unit 7 in an attempt to confirm the apparent negative excursions in both carbon and oxygen values found in our initial sampling at Zumaya in 1997. Neither minimum showed up in our sampling at Sopelana, further confirming that the two isolated low carbon values at Zumaya probably do not represent real excusions. The carbon curve at Sopelana fluctuates very little (values vary from +1.48 to +1.83 ‰ but most values lie around + 1.6 ‰) and superimposes on the carbon curve from Zumaya almost exactly. Although lithostratigraphic correlation between the two localities is insufficiently precise to correlate individual points, the two curves do show similar trends apart from the two very low values at Zumaya.
The oxygen curve at Sopelana is offset to slightly less negative values compared with Zumaya, but shows some similarities through unit 7. It starts with the least negative value of all our samples (-2.3 ‰ whereas most values lie around -3.0 ‰). Again the two curves appear to show similar trends suggesting that we are detecting at least some of the original signal. However, the Sopelana values are consistently offset by approximately +0.5 ‰ with respect to the Zumaya curve.

Discussion
From the limited information we have for two sites in Northern Spain, it would seem that carbon values reached a peak low in the Lower Maastrichtian and declined towards the Lower - Upper Maastrichtian boundary. A smoothed curve which omits the two anomalously low values, shows two minima at about 1.7 ‰ within Wiedmann’s unit 7, the upper of which coincides with the local first appearance of genuine Abathomphalus mayaroensis (Bolli). Immediately above this minimum, values increase relatively rapidly to a peak of about 2.3 ‰ near the top of Wiedmann’s unit 8 (Wiedmann, 1988). Thereafter, there is a general decline to about 2.0 ‰ through unit 9 and a steeper decline into unit 10. A smoothed oxygen curve shows a similar pattern. Values start at around -3.5 ‰ in Wiedmann’s unit 5, rise to -3.0 ‰ in unit 6. Thereafter, they decline to about -3.75 ‰ low in unit 7 where there is a second minimum also about -3.75 ‰ just below the first appearance of Abathomphalus mayaroensis (Bolli). Above this they rise slightly to the boundary between units 7 and 8, and then remain more or less constant at -3.5 ‰ through units 8, 9 and 10. The double minimum in both oxygen and carbon curves just below the Lower - Upper Maastrichtian boundary may well be a good marker and should be sought in other Cretaceous sections.

References
Lamolda, M. A., Orue-Etxebarria, X. and Proto-Decima, F. 1983. The Cretaceous-Tertiary boundary in Sopelana (Biscay, Basque Country). Zitteliana, 10, 663-670.
Marshall, C. R. and Ward, P. D. 1996. Sudden and gradual molluscan extinctions in the latest Cretaceous of Western European Tethys. Science, 274, 1360-1363.
Ward, P. D. and Kennedy, W. J. 1993. Maastrichtian ammonites from the Biscay region (France, Spain). Journal of Palaeontological Memoir, 34, 56 pp.
Ward, P. D., Kennedy, W. J., MacLeod, K. G. and Mount, J. F. 1991. Ammonite and inoceramid bivalve extinction patterns in Cretaceous/Tertiary boundary sections of the Biscay region (southwestern France, northern Spain). Geology, 19, 1181-1184.
Wiedmann, J. 1988. The Basque coastal sections of the K/T boundary - A key to understanding “mass extinctions” in the fossil record. In Lamolda, M. A., Kauffman, E. G. and Walliser, O. H. (editors), Paleontology and evolution: extinction events. Revista Española de Paleontología, n. Extraordinario, pp. 127-140, Bilbao.

BENTHIC FORAMINIFERS FROM THE CONIACIAN-SANTONIAN BOUNDARY INTERVAL AT OLAZAGUTÍA, SPAIN

Danuta Peryt¹ and Marcos A. Lamolda²

¹Instytut Paleobiologii, Polska Akademia Nauk, ul. Twarda 51/55, 00-818 Warszawa, Poland
e-mail: d.peryt@twarda.pan.pl
²Facultad de Ciencias, Universidad del Pais Vasco, Campus de Lejona, 48940 Lejona, España; e-mail: gpplapam@lg.ehu.es

The studied interval extends from 8.6 m below to 27.8 m above the Coniacian-Santonian boundary and encompasses the uppermost Dicarinella concavata and lowermost Dicarinella asymetrica globotruncanid zones or the uppermost Pseudotextularia nuttali and lowermost Sigalia carpatica heterohelicid zones (Lamolda et al., 1999).
Benthic foraminiferal assemblages in the studied interval are moderately to highly diverse. A total of 48 benthic taxa were identified at the generic or specific level. The identified taxa represent 4 suborders (Textulariina, Lagenina, Robertinina, Rotaliina), 13 superfamilies and 23 families. Representatives of Textulariina and Rotaliina dominate assemblages.
In the studied interval P/B ratio values vary from 50 - 77%; H(S), the Shannon-Weaver heterogeneity index, is generally high : >2.0; number of benthic species in the assemblages exceeds 20 (20-35) and the proportion of agglutinated tests is generally high (49 - 74%). Infaunal morphogroups form 50 – 70% of benthic foraminiferal assemblages.
P/B ratio values and H(S) diversity index indicate outer shelf – upper bathyal environment. The high percentages of agglutinated tests reflect probably a fairly high, fine-grained clastic input toward the deep basin and the high proportions of infaunal morphogroups indicate mesotrophic to eutrophic conditions with poorely oxygenated bottom waters.
Neoflabellina suturalis (Cushman) and Neoflabellina gibbera (Wedekind), species which appear for the first time at the base of Santonian (Koch, 1977; Salaj, 1980; Lamolda & Hancock, 1996), occur at Olazagutía. Neoflabellina suturalis is recorded from the entire studied interval, while Neoflabellina gibbera appears for the first time at the base of the Dicarinella asymetrica Zone.

References:
Koch, W. 1977. Stratigraphie der Oberkreide in Nordwestdeutschland (Pompeckjsche Scholle). Geologisches Jahrbuch, A, 38, 3-123.
Lamolda, M. & Hancock, J., 1996. The Santonian stage. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, 66, 95-102.
Lamolda, M. A., Melinte, M. C. & Peryt, D. 1999. Datos micropaleontológicos preliminares sobre el límite Coniaciense-Santoniense en Olazagutía (Navarra, España). Revista Española de Micropaleontologia, 31, 337-345.
Salaj, J. 1980. Microbiostratigraphie du Crétacé et du Paléogène de la Tunisie septentrionale et orientale (Hypostratotypes tunisiens). Institut Geologique de Dionyz Stur, Bratislava, 1-238.

CONIACIAN - SANTONIAN PLANKTONIC FORAMINIFERA BIOEVENTS IN THE SOUTHERN OCEAN RECORD

Maria Rose Petrizzo

Dipartimento di Scienze della Terra, Università degli Studi di Milano, via Mangiagalli 34, 20133 Milano, Italy;
e-mail: mrose@e35.gp.terra.unimi.it

Cretaceous planktonic foraminiferal assemblages from the high latitude areas typically exhibit low diversity and are mainly comprised of long-ranging taxa of simple morphology, whereas the Tethyan assemblages are characterised by an abundant and highly diverse fauna. Because of these differences most of the Tethyan marker taxa are absent in the Southern Ocean record, preventing application of the Tethyan biostratigraphic scheme. Moreover, the establishment of a detailed Late Cretaceous planktonic foraminiferal biozonation of the southern latitudes has been hampered by a rather incomplete sedimentary record due to overall poor recovery and the presence of several hiatuses.
A comparative biostratigraphic analysis of planktonic foraminiferal distribution from the most recent Ocean Drilling Program (ODP) drill-sites in the Southern Ocean has improved the Cretaceous deep-sea database. This allows recognition of a similar sequence of bioevents occurring in the middle (Exmouth Plateau, 47° S paleolatitude) and high latitude (Kerguelen and Naturaliste Plateau, 50° S paleolatitude; Northeast Georgia Rise and Falkland Plateau, 58° S paleolatitude) sedimentary sequences of the Southern Ocean area. These bioevents are evaluated in terms of their value as zonal markers for a regional planktonic foraminiferal biostratigraphic zonation; some are shown to be possibly isochronous across many latitudes and hence useful for worldwide correlation. They are, in stratigraphic order: (1) the last occurrence (LO) of Falsotruncana maslakovae in the Coniacian, which seems isochronous across latitudes; (2) the first occurrence (FO) of Heterohelix papula, which is supposed to be coincident with the FO of the large heterohelicids (Sigalia and ventilabrellids) at low latitude, and useful for approximating the Coniacian/Santonian boundary; (3) the FO of Dicarinella asymetrica in the middle latitudes sites, which falls slightly above the FO of H. papula and is interpreted to be close to the base of the Santonian (as in the Tethyan record); (4) the FO of Globotruncana ventricosa, the occurrence of which in the Santonian confirms that its value as a zonal marker for the mid Campanian is restricted to the Tethyan area; (5) the extinction of the marginotruncanids in the upper Santonian, which here precedes the LO of D. asymetrica; their last record in the Tethys is therefore younger as it falls in the lower Campanian.

THE APPEARANCE OF CONTUSOTRUNCANA FORNICATA FOR SUBDIVIDING THE DICARINELLA CONCAVATA ZONE. A PROPOSAL

Isabella Premoli Silva and Maria Rose Petrizzo

Dipartimento di Scienze della Terra, Università degli Studi di Milano, via Mangiagalli 34, 20133 Milano, Italy;
e-mails: Isabella.Premoli@unimi.it; mrose@e35.gp.terra.unimi.it

The recent multidisplinary study on Late Cretaceous succession carried out in Tunisia (Robaszynski et al., 1990) proved that the Dicarinella concavata Zone, based on the appearance of the nominal taxon, begins in the late middle Turonian and extends up to slightly above the base of the Santonian, spanning more than 5 my-long interval. According to the literature, little to no changes in planktonic foraminiferal assemblages have been detected within the D. concavata Zone preventing a subdivision in subzones to better stratigraphically constrain this long interval. However, looking at the planktonic foraminiferal distributions published so far two genera seem to apppear within the D. concavata Zone, namely Globotruncana and Contusotruncana. If in one hand the representatives of the former genus are often hard to identify correctly especially in thin section, on the other hand the species Contusotruncana fornicata cannot be misinterpreted because of the combination of round-shaped initial chambers, moderately spiro-convex profile and double-keeled margin. Here we propose to split the D. concavata Zone in two subzones, with the base of the higher subzone placed at the first occurrence of C. fornicata. Even though a firm correlation between macrofossil and planktonic foraminiferal biostratigraphies through carbon isotope stratigraphy is still missing, it appears that the C. fornicata event is Coniacian in age.

Reference
Robaszynski, F., Caron, M., Dupuis, C., Amedro, F., González-Donoso, J.M., Linares, D., Hardenbol, J., Gartner, S., Calandra, F., and Deloffre, R., 1990, A tentative integrated stratigraphy in the Turonian of central Tunisia: formations, zones and sequential stratigraphy in the Kalaat Senan area: Bulletin Centre de Recherches Expl. Prod. Elf-Aquitaine, v. 14, p. 213-384.

COMPARATIVE MICROFOSSIL CHRONOSTRATIGRAPHY OF THE CONIACIAN-SANTONIAN BOUNDARY FROM THE WESTERN INTERIOR, USA (AUSTIN AND NIOBRARA FORMATIONS) AND THE U.K. CHALK.

Paul J. Sikora¹, Richard W. Howe¹ and Andrew S. Gale<sup>2

1</sup>Energy & Geoscience Institute at the University of Utah; 423 Wakara Way, Ste. 300, Salt Lake City, UT 84108, USA; psikora@egi.utah.edu; rhowe@egi.utah.edu
²Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K.; asg@mailserver.nhm.ac.uk

At the 2nd International Symposium on Cretaceous Stage Boundaries held in Brussels in September 1995, three candidates for Coniacian/Santonian boundary stratotype section were made from Spain, the United Kingdom and the United States (Lamolda and Hancock, 1996). However, the Santonian Working Group (SWC) felt that no formal recommendation could be made until the biostratigraphy of these sections was better known and integrated. In order to facilitate such a recommendation, high-resolution, multidisciplinary micropaleontologic analyses (planktonic foraminifera and calcareous nannofossils) are conducted on two of the proposed stratotype sections: an Austin Chalk composite section incorporating the Ten-Mile Creek section in northern Texas, USA; and, a U.K. chalk section equivalent to the Seaford Head outcrop.
In addition, a third Coniacian/Santonian boundary section from the Niobrara Chalk of western Kansas, USA, is also analysed and correlated to the two potential boundary stratotype sections. This Niobrara interval is part of a 210m composite section of Coniacian to lower Campanian chalk (Hattin, 1982) that exhibits excellent potential for cyclostratigraphic absolute age calibration. Short-term cyclicity within the Niobrara section on the order of precessional resolution (~20 kyr) has been defined through carbonate content and magnetic susceptibility measurements. Such data will ultimately result in a recalibration of the duration of the Coniacian and Santonian stages and a more precise absolute age placement for the Coniacian/Santonian boundary. The Niobrara cycles are correlated to the potential boundary stratotypes in Texas and England via graphic correlation against the Composite Standard Database of the University of Utah. This involves an absolute age integration for all three sections for both microfossil and macrofossil datums, the latter including the boundary datum proposed by the SWC (Lamolda and Hancock, 1996); i.e., the FAD of the bivalve Claderoceramus undulatoplicatus (Roemer).

References
Hattin, D.E., 1982. Stratigraphy and depositional environment of the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas. Kansas Geol. Surv. Bulletin 225, 108 pp.
Lamolda, M.A., and Hancock, J.M., 1996. The Santonian Stage and substages: in, Rawson, P.F., Dhondt, A. V., Hancock, J.M., and Kennedy, W. J. Proceedings “Second International Symposium on Cretaceous Stage Boundaries” Brussels 8-16 September 1995. Bull. de l’Inst. Royal des Sci. Natur. de Belgique, v. 66, suppl., pp. 95-102.

STRATIGRAPHY OF THE SANTONIAN TO LOWER CAMPANIAN IN JAPAN: REVIEW SINCE 1995

Seiichi Toshimitsu¹, Takashi Hasegawa² and Ken Tsuchiya<sup>2

1</sup> Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba 305-8567, Japan
(e mail: s.toshimitsu@aist.go.jp)
² Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
(e mail: jh7ujr@kenroku.kanazawa-u.ac.jp, sukoya@d1.dion.ne.jp)

At the Brussels Symposium in 1995, one of us (S.T.) reported the Coniacian to Maastrichtian stratigraphy in Japan (Toshimitsu, 1995). Unfortunately, these Japanese stages do not yield the global basal marker fossils of each stage defined by SCS (Rawson et al., 1996 eds.), except for the basal Coniacian.
After the Brussels Symposium, one of us (T.H.) and co-workers reported the K-Ar age of the lower Camapnian (the lower part of the Inoceramus (Platyceramus) japonicus Zone) of southern Hokkaido, i.e., 82.2 ± 0.6 Ma (in Shibata and Uchiumi, 1995). The base of I. (P.) japonicus Zone is almost the same level that one of Submortoniceras cf. condamyi – Menabites mazenoti Zone and the first occurrence of typical Globotruncana arca in northwestern Hokkaido, correlated with the base of the Campanian in Japan (Toshimitsu et al., 1998; Toshimitsu and Hasegawa, 2000). Recently, Moriya et al. (2001) reported the occurrence of early Campanian planktonic foraminiferal assemblage consisting of Globotruncana arca, G. linneiana, Rosita fornicata and R. patelliformis, in the lowest part of the I. (P.) japonicus Zone of northwestern Hokkaido. However, the I. (P.) japonicus Zone is assigned to the uppermost part of the magnetic normal polarity chron 34 (Toshimitsu and Kikawa, 1997).
The Coniacian/Santonian stage boundary in Japan is situated at the boundary between the Inoceramus uwajimensis – I. mihoensis Zone and the I. amakusensis Zone, and to the base of the Texanites collignoni Zone (e.g., Toshimitsu et al., 1995), though there is an objection (Lamolda and Hancock, 1996). Recently, Tsuchiya and Hasegawa (2001) preliminarily reported the carbon isotope profiles of the middle Turonian to lower Santonian in the central and northwestern Hokkaido, in comparison with inoceramid biostratigraphy. The negative shift segment of carbon isotope profile is found in the I. hobetsensis Zone (middle Turonian), the stable value segment in the upper part of the I. hobetsensis Zone to the lower part of the I. uwajimensis Zone (upper Turonian to lower Coniacian), and the gradual positive shift segment in the middle part of the I. uwajimesis Zone to the lower part of I. amakusensis Zone (middle Coniacian to lower Santonian), which is harmonious with the result in England (Jenkyns et al., 1994) . It is expected that the future detailed research on carbon isotope stratigraphy may clarify the precise position of the basal Santonian in Japan.

References:
Jenkyns, H., Gale, A. & Corfield, M. (1994): Carbon- and oxygen- isotope stratigraphy of the English Chalk and Italian Scaglia and its palaeoclimatic significance. Geol. Mag. 131, 1-34.
Lamolda, M. A. & Hancock, J. M. (1996): The Santonian Stage and substages. Bull. Inst. r. Sci. nat. Belg., Sci. Terre, 66-Supp., 95-102.
Moriya, K., Nishi, H. & Tanabe, K. (2001): Age calibration of megafossil biochronology based on Early Campanian planktonic foraminifera from Hokkaido, Japan. Paleont. Res. 5, 277-282.
Rawson, P. F., Dhondt, A. V., Hancock, J. M. & Kennedy, W. J. (1996 eds): Proceedings “Second International Symposium on Cretaceous Stage Boundaries” Brussels 8-16 September 1995. Bull. Inst. r. Sci. nat. Belg., Sci. Terre, 66-Supp., 117p.
Shibata, K. & Uchiumi, S. (1995): K-Ar age results-5 –New data from the Geological Survey of Japan–. Bull. Geol. Surv. Japan 46, 643-650.
Toshimitsu, S. (1995): Coniacian to Maastrichtian stratigraphy in Japan. Abst. Vol. 2nd Int’n. Symp. Cretaceous Stage Boundaries. Subcommission on Cretaceous Stratigraphy, 120.
Toshimitsu, S. & Hasegawa, T. (2000): Notes on stratigraphy of the upper Santonian to lower Campanian (Upper Cretaceous) of Azumi of Hobetsu Town and Noborikawa of Yubari City, central Hokkaido. Bull. Hobetsu Mus. 16, 1-7.
Toshimitsu, S. & Kikawa, E. (1997): Bio- and magnetostratigraphy of the Santonian-Campanian transition in northwestern Hokkaido, Japan. Mem. Geol. Soc. Japan 48, 142-151.
Toshimitsu, S., Maiya, S., Inoue, Y. & Takahashi, T. (1998): Integrated megafossil –foraminiferal biostratigraphy of the Santonian to lower Campanian (Upper Cretaceous) succession in northwestern Hokkaido, Japan. Cret. Res. 19, 69-85.
Toshimitsu, S., Matsumoto, T., Noda, M., Nishida, T. & Maiya, S. (1995): Towards an integrated mega-, micro- and magneto-stratigraphy of the Upper Cretaceous in Japan. Jour. Geol. Soc. Japan 101, 19-29.
Tsuchiya, K. & Hasegawa, T. (2001): Integration of carbon isotope profiles and inoceramid biochronology from the Cretaceous Yezo Group. Abst. with Programs, 2001 Ann. Meet., Palaeont. Soc. Japan, 170.

BIOSTRATIGRAPHY OF INOCERAMIDS AT THE CONIACIAN/SANTONIAN BOUNDARY IN GERMANY

by Karl- Armin Tröger

University of Mining and Technlogy "Bergakademie Freiberg" - Geological Institute , D –09596 Freiberg/ Sachsen, Zeuner str. 12 - Meißer building. Germany. e mail: troeger@geo.tu-freiberg. de

Heinz (1928) used for the first time the vertical distribution of inoceramid species in a profile situated at Lüneburg (Lower Saxony) for fixing boundaries in the Coniacian - Santonian interval. The boundary between the so-called Lower and Upper Emscherian was established by means of the FOD of Inoceramus undulato-plicatus F.Roemer var. michaeli Heinz.

The same stratigraphic division was used by Stolley (1930 ) and Riedel (1931, 1933, 1934, 1937, 1942) - quotation in Seitz (1965, text-fig. 7). Seitz (1965 ) introduced the following stratigraphic division by especially investigating shaft profiles in the Münsterland region (Münsterland basin):

Table 2
Lower Santonian	Undulatoplicatus zone    (=Undulatoplicatus Faunenzone)    ----------------------------------------    Sphenoceramen-Teilzone	-- Cladoceramus undulatoplicatus (Roemer)     Sphenoceramus pachti (Arkhanguelsky) -----------------------------------------------------     Sphenoceramus cardissoides (Goldfuss)
________________ Upper Coniacian	__________________________________ - - -	___________________________________ -- Magadiceramus subquadratus (Schlüter)

Sections with Coniacian through Santonian sequences as in Germany are visible in the following areas: Northwest German - Polish Basin , Münsterland Basin , Subhercynian Cretaceous Basin , North Sudetic Basin including the Cretaceous of south Brandenburg and the alpine region . Outcrops are rare . The Coniacian / Santonian boundary interval is mainly exposed in shafts and wells.
Investigation of 12 wells ( Troeger & Ulbrich - unpublished report ) in the middle part of the NW German -Polish Basin and one shaft profile (Grimberg IV at Bergkamen - Münsterland - Troeger 1974) led to the following results mainly visible in tab. 3.

NANNOPLANKTON AND FORAMINIFERA IN CONIACIAN-SANTONIAN BOUNDARY SECTIONS IN AUSTRIA

Michael Wagreich

Institut für Geologie, Universität Wien, A-1090 Vienna, Austria. e mail: michael.wagreich@univie.ac.at

Several Coniacian-Santonian boundary sections are known in the Gosau Group of the Northern Calcareous Alps of Austria. Two continous sections in the Salzkammergut were investigated in detail for calcareous nannofossils and foraminifera. The Stöcklwaldgraben section NW of Gosau comprises a gradational change from shallow water silty marls of the Streiteck Formation to shelf marls of the Grabenbach Formation. The Coniacian-Santonian boundary interval is defined by macrofossils, i.e. the first appearance of Texanites quinquenodosus. Below, the presence of Volviceramus involutus indicates a Coniacian age, followed by the first Sphenoceramus cardissoides slightly above the first Texanites. Planktonic foraminifera assemblages indicate the Dicarinella concavata Zone. Both D. cf. asymetrica and Sigalia carpatica appear several meters above the first Texanites species. Nannofossil assemblages indicate the Micula decussata standard zone CC14, above the FO of M. decussata and Lithstrinus grillii, and below the first occurrence of Lucianorhabdus cayeuxii. Reinhardtites anthophorus, which normally defines the base of CC15, is already present rarely in lower Coniacian strata. According to the Burnett zonation, the Coniacian-Santonian boundary lies within zone UC11a/b.
The Nussensee section near Bad Ischl comprises a gradual deepening trend around the Coniacian-Santonian boundary interval within the Grabenbach Formation. Thus, macrofossils are extremely rare in the upper part of the section - only a mid-Coniacian ammonite assemblage including Peroniceras tridorsatum and Platyceramus mantelli mantelli could be recognized. The lower boundary of the Santonian is placed at the FO of Sigalia carpatica, which is followed by the FO of D. asymetrica several meters higher.
The evolution of holococcoliths was quantitatively investigated in both sections. Lucianorhabdus maleformis and straight Lucianorhabdus predominate Coniacian assemblages. A few meters above the base of the Santonian first tapered morphotypes transitional from L. maleformis to L. cayeuxii occur.

INOCERAMID FAUNA AND BIOSTRATIGRAPHY OF THE UPPER CONIACIAN-LOWER SANTONIAN OF THE PUEBLO SECTION (SE COLORADO, US WESTERN INTERIOR)

Ireneusz Walaszczyk¹ & William A. Cobban<sup>2

1</sup>Institute of Geology, University of Warsaw, Al. Zwirki i Wigury 93, PL-02-089 Warszawa, Poland
<e mail: walas@geo.uw.edu.pl>
²70 Estes Street, Lakewood, Colorado 80226, USA

Upper Cretaceous strata as exposed at Pueblo, SE Colorado, offer apparently continuous succession of the Upper Coniacian and Lower Santonian, with good paleontological record. The succession was studied in detail by Scott & Cobban (1964), who also discussed the inoceramid fauna. The details given below result from recent revision of the Middle-Upper Coniacian and Santonian inoceramids of the US Western Interior (Walaszczyk & Cobban in prep.).
Although Middle/Upper Coniacian and Santonian inoceramid fauna of the US Western Interior was long known to be very close to the European one (e.g. Scott & Cobban 1964, Kauffman et al. 1993), our study showed these two to be virtually identical. On one hand a whole series of species described in Europe is recognized to be present also in US Western Interior, and on the other, forms like Platyceramus platinus (Logan, 1893) or Inoceramus stantoni Sokolov, 1914, cited commonly as examples of “American” species, are shown to represent species groups well known but differently called in Europe.
The Upper Coniacian and Lower Santonian are contained within the lower shale, lower limestone, and middle shale units of the lower Smoky Hill Member of the Niobrara Formation. The Coniacian/Santonian boundary lies in the lowermost part of the middle shale unit.
The base of the Upper Coniacian is placed at the appearance level of Magadiceramus subquadratus, what is noted relatively low in the lower shale unit. The Middle Coniacian seems to be very thin in the Pueblo section, and the co-occurrence of Volviceramus involutus (Sowerby, 1823) with Cremnoceramus deformis deformis (Meek, 1876) in the topmost part of the shale and limestone unit, suggest a gap spanning the topmost part of the Lower Coniacian and possibly part of the Middle Coniacian (see also Walaszczyk & Cobban 2000).
Upper Coniacian succession is highly fossiliferous, with a number of species of the genera Volviceramus Stoliczka, Platyceramus Seitz, Magadiceramus Heinz and Inoceramus Sowerby. Although not found in the Pueblo section, it is also where first sphenoceramids appear.
The entrance of Cladoceramus undulatoplicatus (Roemer, 1852) [including C. undulatoplicatus michaeli (Heinz)], taken as the lower boundary of the Santonian stage and located in the lowermost part of the middle shale unit, is marked by a common occurrence of Roemer’s species. It is accompanied here by Platyceramus heinei (Seitz, 1961), Cordiceramus arnoldi (Seitz, 1967), Cordiceramus ex gr. cordiinitalis (Seitz, 1961) and Inoceramus sp. Higher in the succession also appears Platyceramus wegneri (Boem, 1915).
The undulatoplicatus-dominated fauna changes in the upper part of the middle shale unit. Starting from bed 19 (numbers after Scott & Cobban 1964) C. undulatoplicatus is no longer recorded, and inoceramid fauna is dominated by cordiceramids: C. cordiformis (Sowerby, 1823), C. bueltenensis (Seitz, 1961), C. brancoiformis (Seitz, 1961), and C. arnoldi (Seitz, 1961). Also occurring are Platyceramus ahsenensis (Seitz, 1961) and “Inoceramus” gladbeckensis Seitz 1961.
Although Late Coniacian and Early Santonian inoceramids are common, taxonomically variable, and apparently rapidly evolving, the details of their vertical distribution are still not sufficiently known to propose a refined inoceramid-based biozonation. At present only two zones traditionally offered for this interval are proposed: the Magadiceramus subquadratus Zone for the Upper Coniacian and the Cladoceramus undulatoplicatus for the Lower Santonian. Both zones are defined as interval zones. Similarly as commonly applied in Europe, the base of the Middle Santonian is placed at the entrance level of Cordiceramus cordiformis.
The base of the C. undulatoplicatus Zone lies in the topmost part of the Scaphites depressus ammonite Zone, and the base of the successive, Cordiceramus cordiformis Zone in the upper part of the Scaphites saxitonianus ammonite Zone.

References
Scott, G. R. & Cobban, W. A. 1964. Stratigraphy of the Niobrara Formation at Pueblo, Colorado. Professional Paper of the United States Geological Survey, 454-L, 1-30.
Walaszczyk, I. & Cobban, W.A. 2000. Inoceramid faunas and biostratigraphy of the Upper Turonian – Lower Coniacian of the Western Interior of the United States. Special Papers in Palaeontology, 64, 1-118.

THE PROBLEM OF THE CONIACIAN – SANTONIAN BOUNDARY IN FAR EASTERN REGIONS OF RUSSIA.

Elena Yazykova¹ and Tatjana Zonova²

¹University of Silesia, Bedzinska str. 60, 41-200 Sosnowiec, Poland; yazykova@wnoz.us.edu.pl
²VNIGRI, Litejny pr. 39, 191104 St.-Petersburg, Russia

The main problem of Cretaceous stratigraphy in far eastern regions of Russia is the recognition of stage and substage boundaries because of the monotonous character of lithology, high degree of fauna endemism and rare finds of cosmopolitan taxa. Consequently, the next problem is the global biostratigrafic correlation. In the Naiba reference section at the south of island, the position of that local Coniacian – Santonian boundary as currently understood is placed at the base of Member 8 of the Bykov Formation. There is a good marker at the top of Member 7. That is the light grey sandstone, which yields a lots of plant detritus with green-grey tuff interlayers traced in Japan (Hirano & Takagi 1995). The last Coniacian ammonite, Peroniceras sp., has been found just above those tuffs. Typical Coniacian species, Pachydesmoceras mihoense, Forresteria (F.) alluaudi and inoceramids from the Inoceramus mihoensis group, occur just below tuff interlayers. The first appearance of Texanites (Plesiotexanites) kawasakii and Inoceramus amakusensis are the two best criteria for the base of Santonian in Sakhalin (Yazykova, 1996, 2002) in spite of both are endemic. That position is suggested by the occurrence of cosmopolitan Desmophyllites diphylloides and Phyllopachyceras forbesianum. Unfortunately, the first appearance of Texanites was rejected from the main marker for the Conacian-Santonian boundary on the Second International Symposium on Cretaceous Stage Boundaries, Brussels, 1995 (Lamolda & Hancock, 1996). However, the primary recommended marker – the lowest occurrence of Cladoceramus undulatoplicatus – can’t be applied in far eastern regions of Russia. Single representatives of Inoceramus sp. aff. Cl. undulatoplicatus are known in Sakhalin from Upper Santonian, and were found with Inoceramus (Platiceramus) japonicus hokkaidoensis and T. (Pl.) kawasakii (Zonova et al. 1993). In addition to problem of Pacific fauna endemism, there is a strong provincialism among the local macrofaunas. For instance, in North-East Russia, neither specimens of I. amakusensis nor representatives of Texanites were found. Meanwhile, Mezopuzosia indopacifica, the species known from Santonian of India, was found in North East Russia with fragments of I. sp. aff. Cl. undulatoplicatus but has never been found in Sakhalin. Eupachydiscus haradai is the species widespread in both Sakhalin and North East, and also is well known from Santonian- Lower Campanian of Japan, Alaska and British Columbia (Yazykova, 1996, 2002). Eupachydiscus haradai Zone could be a good marker in Pacific Realm due to numerous specimens of zonal species. The problem of correlation within and outside the Pacific Realm could be facilitated by refined studies of bioevents. Gradual decreasing of the taxonomic diversity of ammonites and inoceramids, observed in the Coniacian succession and possibly caused by new regression and slight fall of temperature (Zakharov et al. 1996, 1999), finished at the beginning of Santonian. Then, taxonomic diversity of macrofauna increased due to rising global sea level and temperature. New taxa appeared that represent new morphotypes. The Coniacian-Santonian faunal turnover, characterized by the same evolutionary trends, takes place in many world areas (Hallam & Wignall 1997). The last but not least question is the recognition of substage boundaries. None of criteria recommended at the International Symposium in Brussels can be applied, because the guide taxa have not been recorded in far eastern regions of Russia. Thus, this problem still needs clarification.

References:
Hallam, A. & Wignall, P.B. 1997. Mass Extinctions and their aftermath. Oxford University Press.320p.
Hirano, H. & Takagi, K. 1995. Cretaceous oceanic anoxias in northwestern Pacific – current conditions and prospect of research. – Proceedings 15th International Symposium of Kyungpook National University. 343-355.
Lamolda, M.A. & Hancock, J.M. with contributions by J.A. Burnet et al. 1996. The Santonian Stage and substages. In: Rawson, P.F., Dhondt, A.V., Hancock, J.M. & Kennedy, W.J. (Eds.): Proceedings “Second International Symposium on Cretaceous Stage Boundaries” Brussels 8 – 16 September 1995. – Bull. Inst. Royal Sci. Natur. Belgique. Sci. Terre, 66-Supp.: 95-102.
Yazykova, E.A. 1996. Post-crisis recovery of Campanian desmoceratacean ammonites from Sakhalin, far east Russia. In: Hart, M.B. (Editor), Biotic Recovery from Mass Extinction Events. Geological Society (London), Special Pablication, 102: 299-307.
Yazykova, E.A. 2002. Ammonite and inoceramid radiations after the Santonian-Campanian bioevent in Sakhalin, Far East Russia. Lethaia, 35, pp.51-60.
Zakharov, JU.D., Ignatyev, V., Ukhaneva, N.G. & Afanaseva, T.B. 1996. Cretaceous ammonoid succession in the Far East (South Sakhalin) and the basic factors of syngenesis. Bulletin de L’Institut Royal des Sciences Naturelles de Belgique. Sciences de la Terre 66, 109-127.
Zakharov, YU.D., Boriskina, N.G., Ignatyev, A.V., Tanabe, K., Shigeta, Y., Popov, A.V., Afanaseva, T.B. & Maeda, H., 1999: Palaeotemperature curve for Late Cretaceous of the north – western circum – Pacific. Cretaceous Resaerch, 20, pp. 685-697.
Zonova, T.D., Kasinzova, L.I. & Yazykova, E.A. 1993: Atlas rukovodjaschih group melovoj fauny Sakhalina [Atlas of the main groups of Cretaceous fauna from Sakhalin]. VSEGEI, 327 pp.

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