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The Valanginian to Aptian Stages - Current Definitions and Outstanding Problems

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The Valanginian to Aptian Stages - Current Definitions and Outstanding Problems © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zobodat.at 4‘>3 Zitteliana 10 493-500 München, I. Juli 1983 ISSN 0373 9627 The Valanginian to Aptian stages - current definitions and outstanding problems Compiled by PETER FRANKLIN RAWSON») Willi 3 tables ABSTRACT Current definitions of the Valanginian to Aptian Stages are tion potential. The I’re-Albian Stages Working Croup is in­ reviewed and some of the outstanding problems outlined. Fi­ stigating study of selected sections in various parts of the nal recommendations on stage boundaries can be made only world to provide an integrated framework ol biostraligraphy after much more strat¡(graphical work has been completed, as and event stratigraphy. the eventual boundaries must have good international correla­ KURZFASSUNG Lin Überblick über die gängigen Definitionen der Stufen barsein. Die Prc-Albian Stagcs Working Group regt an, ms vom Valangin bis zum Apt wird gegeben und einige wichtige gewählte Profile in verschiedenen Peilen der Welt zu unterst! Probleme hervorgehoben. Lndgülligc Empfehlungen zu Stu­ ehen, um so den allgemeinen Rahmen liii eine Ncudelinition fengrenzen sind z. Zt. noch nicht möglich. Dazu sind noch der Stufen auf der Grundlage der Biostraligraphie und der weitere stratigraphische Untersuchungen erforderlich, denn Lvenl-Straiigraphic zu schaffen. die fcstzulcgendcn Grenzen müssen international korrelier­ I. INTRODUCTION This review has been compiled on behalf of the Prc-Albian boundaries and to improve the usage of stage names in re­ Stages Working Group of the Subcommission on Cretaceous gions away from stratotype sections." Stratigraphy. The primary role of the working group is to cla ­ Thus our fundamental philosophy is first to make objective rify, and to improve where necessary, the definition and correlations between regions and only then to redefine stages boundaries of the Valanginian to Aptian Stages. This cannot and their boundaries. be achieved simply by describing a stratotype and selecting As a first step towards priority I, several key sections were boundaries because such a procedure takes no account of the identified in western Rumpe. At its second meeting (Münster international correlation potential of the stages so defined. 1978, see Newsletter 3), the group agreed to concentrate ini ­ Hence at its first meeting in 1 lannover in 1977 (see the group’s tially on investigating correlation of I lautcrivian strata across Newsletter 2), the working group agreed on the following Europe, in collaboration with the re-investigation of the Jura priorities: Hautcrivian by a research group co-ordinated by Dr. J. Ri-: 1. “To establish inter-regional correlation more precisely mank. It is intended that first results on the investigation of than before, using all possible methods (macro- and mi­ key sections will be given at a meeting of the Subcommission crofossils, event stratigraphy, etc.)” on Cretaceous Stratigraphy in Copenhagen in 1983. In the 2. “As a result of more accurate correlation, to clarify (and if meantime it seems appropriate to summarise current de-fini necessary to improve) the definition of stages and stage tions of the Valanginian to Aptian Stages and to demonstrate some of the outstanding problems. For the sake of using a *) P. P. Rawson, Department of Geological Sciences, Queen Mary common “language”, we hope that fellow workers will conti­ College, Mile P.nd Road, London Pd 4NS, P.ngland. nue to use stage names in the current sense ('Table I) until im- © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zobodat.at 494 proved definitions are agreed. Specialists who insist on using nardo (Lyon), R. C ombemorfl (Lyon), P. D onze (Lyon), T. them in a different sense are urged to explain their different N. G orbatchik (Moscow), J. E. van H inte (Amsterdam), usages. Ph . Hoedemaeker (Leiden), L. M emmi (Tunis), F. A. M idd- The following members of the working group assisted in lemiss (London), J. Remane (Neuchátel), J.-P. T hieuloy this compilation, though final responsibility for the wording (Grenoble) and M. R. A. T homson (Cambridge). rests with the compiler: D. J. Batten (Aberdeen), R. Bus- II. EARLY CRETACEOUS BIOGEOGRAPHY AND THE STRATOTYPE AREAS STAGE ZONE FRANCE ENGLAND/NORTH GERMANY Colchidites sp. Parancyloceras bidentatum & P. scalare Simancyloceras stolleyi UPPER Heteroceras astieri "Ancyloceras" innexum & BARREMIAN Hemihoplites feraudi Simancyloceras pingue Emericiceras barremense P aracrioceras denckmanni Paracrioceras elegans LOWER Moutoniceras sp. "Hoplocrioceras" fissioostatum BARREMIAN Pulchellia compressissima Paracrioceras raricostatum Spitidiscus hugii S. (C.) variabilis / Simbirskites „ \ . (Craspedodiscus) Pseudothurmannia angulicostata S. (S.) marginatus ^ / discofalcatus UPPER Plesiospitidiscus ligatus S. (Craspedodiscus) gottschei HAUTERIVIAN Subsaynella sayni S. (Kilanov;skia)_ speetonensis /sta ffi __ Lyticoceras nodosoplicatus Simbirskites (Speetonioeras) inversum Olcostephanus .jeannoti LOWER Endemoceras regale Crioceratites loryi HAUTERIVIAN Endemoceras noricum Acanthodiscus radiatus Endemoceras amblv°-onium Neocomites (Teschenites) Olcostephanus spp. callidiscus Dicostella tuberculata UPPER Dichotomites bidichotomoides Himantooeras trinodosum VALANGINIAN Dichotomites triptychoides Dichotomites orassus Saynoceras verrucosum D. (Prodichotomites) polytomus ,D. (Prodichotomites) hollwedensis Polyptyohites sphaeroidalis Thurmanniceras campylotoxus Polyptychites clarkei Poljrptychites multicostatus Polyptychites pavlowi ilatylenticeras involutum Thurmanniceras pertran sien s Platylenticeras heteropleurum LOVER P la ty le n tic e ra s robustura Thurmanniceras otopeta VALANGINIAN Table I . Valanginian to Barremian standard zones of south-east France, and the approximate correlation with the north-west European “boreal” Valanginian and Hauterivian. (Correlation afterKEMPER et al., 1981). No correlation between Barremian zones is intended. © Biodiversity Heritage Library, http://www.biodiversitylibrary.org/; www.zobodat.at 495 During the Early Cretaceous there were two distinct faunal The historical type areas of the Valanginian to Aptian Sta­ realms in the northern hemisphere, the Tethyan and Boreal. It ges are in the Swiss Jura and south-east France, and are cha­ is difficult to attempt a global summary of Early Cretaceous racterised predominantly by Tethyan ammonites. Thus the biogeography because many taxonomic groups have not been main problem in Early Cretaceous stage definition lies in try­ investigated adequately, but K auffman (1979) has given a ge­ ing to correlate with the Boreal Realm. Primary clues come neral review, and for bivalves (K auffman, 1973) and ammoni­ from areas of faunal overlap (e. g. parts of Europe). The bio­ tes (Rawson, 1981) subdivision of the realms can be attempt­ stratigraphy of areas outside the type regions of the stages is ed. Valanginian to Aptian biostratigraphy is based primarily beyond the scope of this paper, but in Table 1 we give the ap­ on ammonites. As in the Tithonian and Berriasian, the Va­ proximate correlation of the Valanginian to Barremian Te­ langinian to earliest Barremian boreal ammonites are clearly thyan zones with the north-west European “boreal” zones to distinct from Tethyan ones, but during most of the Barremian illustrate the nature of the problem. The correlations achieved and Aptian there were no distinctively boreal subfamilies and so far suggest that some of the classic stage boundaries are of in the rare marine sections the northerly faunas were only de­ no inter-regional correlative value and therefore need to be al­ pauperated versions of the Tethyan ones. tered if they are to be equally applicable to both realms. III. DEFINITION OF STAGES THE VALANGINIAN STAGE b) Le calcaire compact ou marbre bâtard. c) Les marnes et brèches marneuses grises et bitumineuses. Author: D esor 1854 The “Marnes à A stieria” were explicitly placed in the Stratotype: The Seyon Gorge near Valangin, Neuchâtel, “Neocomian” (which became the Hauterivian of R ene- Switzerland. vier, 1874) by D esor and Gressly (1859, p. 36). It is also interesting to note that the first detailed descrip­ H ypostratotype: Roadside section near Angles (Al- tion of the succession at the type locality did not appear pes-de-Haute Provence, south-east France); Barret-le-Bas until the end of the century (Baumberger and M oulin, (Hautes-Alpes, south-east France) provides a complementary 1899). reference for the Lower Valanginian (Busnardo et al., 3. Logically, Renevier therefore included the “Marnes à 1979). A stieria” in his Hauterivian Stage. It is only since Baum­ Original definition: D esor (1854, p. 175) regarded all berger (1901, p. 21) that it has become general usage to the “Neocomian” beds beneath the “Marnes de Hauterive” as place them in the Valanginian. corresponding with Campiche’s “Neocomien inférieur”, and for this subdivision proposed (p. 177) the stage name “Valan- Development of the concept of the Valanginian gien” (“Valanginien” in the title of the paper). Thus the Va­ Stage: The early Cretaceous sediments of the Jura Moun­ langinian embraced all the post-Jurassic rocks to the base of tains accumulated on a shallow shelf. Some lithological units are thin, condensed and laterally discontinuous, especially the “Marnes de Hauterive”. those lying between the “Calcaire Roux” and the “Marnes de There are three important points to note with reference to Hauterive” . Early biostratigraphic correlation was based the definition of the
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