University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Earth and Atmospheric Sciences, Department Papers in the Earth and Atmospheric Sciences of 1996 Upper Cretaceous Calcareous Nannofossil Biostratigraphy and Paleoceanography of the Southern Ocean David K. Watkins University of Nebraska-Lincoln, [email protected] Sherwood W. Wise Jr. Florida State University James J. Popsichal Florida State University Jason Crux BP Exploration Follow this and additional works at: https://digitalcommons.unl.edu/geosciencefacpub Part of the Earth Sciences Commons Watkins, David K.; Wise, Sherwood W. Jr.; Popsichal, James J.; and Crux, Jason, "Upper Cretaceous Calcareous Nannofossil Biostratigraphy and Paleoceanography of the Southern Ocean" (1996). Papers in the Earth and Atmospheric Sciences. 258. https://digitalcommons.unl.edu/geosciencefacpub/258 This Article is brought to you for free and open access by the Earth and Atmospheric Sciences, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in the Earth and Atmospheric Sciences by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Watkins, Wise, Pospichal & Crux in Microfossils and Ocean Environments, Moguilevsky & Whatley, eds. Proceedings of the "ODP and the Marine Biosphere" International Conference (Aberystwyth, Wales, April 19-21, 1994) Copyright 1996, University of Wales. Used by permission. 5.4 Upper Cretaceous calcareous nannofossil biostratigraphy and paleoceanography of the Southern Ocean David K. Watkins l , Sherwood W. Wise, Jr.2, James J. Pospichal2, Jason Crux3 1Department of Geology, University of Nebraska, Lincoln, NE 68588-0340, USA 2Department of Geology, Florida State University, Tallahassee, Florida 32306, USA 3BP Exploration, 5151 San Felipe, Houston, Texa, USA ABSTRACT Nannofossil data from the Naturaliste Plateau from these assemblages, but relatively few «5) (DSDP Legs 26 & 28), Falkland Plateau (DSDP high-latitude endemic species are evident. In gen­ Legs 36 & 71), Maud Rise (ODP Leg 113), North­ eral, these can be characterized as somewhat depau­ east Georgia Rise (ODP Leg 114), and Kerguelen perate low latitude assemblages with the addition of Plateau (ODP Leg 120) yield a set of consistent, a few high latitude species. Biostratigraphical sub­ reliable biohorizons that form the basis of a revised division of this interval is based only on cosmopoli­ calcareous nannofossil zonation for the Southern tan taxa used in more low latitude zonations. A Ocean Upper Cretaceous. Analysis of this zonation substantial disconformity separates the Lower and indicates significant changes in the circum-Antarc­ Upper Campanian throughout the Southern Ocean tic climatic regime during the Campanian and sites drilled to date. A disconformity of similar Maastrichtian that foreshadow the more dramatic biostratigraphical placement and hiatus has also climatic shifts ofthe Palaeogene. Calcareous nanno­ been identified on the Western Australian margin. fossils from the Turonian through the Lower Cam­ Above this disconformity, there is a significant in­ panian of the studied sections are characterized by crease in the number of austral or bipolar species in low diversity assemblages consisting largely ofcos­ the Upper Campanian and Maastrichtian. Evolu­ mopolitan species. Low-latitude taxa are absent tionary radiations within the genera Biscutum and Watkins, Wise, Pospichal & Crux in Microfossils and Ocean Environments, Moguilevsky & Whatley, eds. Proceedings of the "ODP and the Marine Biosphere" International Conference (Aberystwyth, Wales, April 19-21, 1994) Copyright 1996, University of Wales. Used by permission. 356 Upper Cretaceous calcareous nannofossils of the Southern Ocean .............}... •..... ~ ··········.....,f.'.,···· ..... ", ..... \ ..... ~~ ..•\.; . ...\ - . .... j .... ...... .............. // ......."..... ..........•..:... ,/,.,'" \" .............:.: .. " :", .......". '" i ". ". /\·:er38~ 698·~.700 ",/ 696~ ··...>.;327 ,···i... .... ..•:.:' .~\ . '1'1'..................'" ................! .__ ·t························ .•......../................• '-; , . ........ :. '.,., . ........ ...... .' ......... \: _ ;.. ,,:' . ~: .... "'., ,." ...... , ,',..., . : .... ..... ..... \ . ........".,.. '.',..~>,.: "...........", .' ········,r ....j . ........>:'- - .. """" """'" """", .. ,/ ··iM.'.I ...\:" j::i?- ~.. ~.'....." .....' """.,... ,.,..'•....•. .... :_.. ", ,/l . : . .... """ .,,::.'::::,: .••••..•,.•.•.•.• ,.'.'.,; .,<.>,:. .. ."::"::;;.::.?: . Fig. 1. Location of the SOllthern high latitude sites discussed in this study. Monomarginatus, and in the Cribrosphaerella­ This is most evident in the progressive exclusion of Psyktosphaera-Nephrolithus plexus in the austral Watznaueria bamesae during the middle to late region indicate that the Southern Ocean was Maastrichtian. A poleward migration of W. bame­ ecologically distinct from low latitude areas during sae during the last 500,000 years of the Maas­ the late Campanian and Maastrichtian. The high trichtian suggests a briefpulse ofwarming just prior degree of provinciality evident during this time to the Cretaceous-Tertiary boundary. suggests the development of a (cooler) Southern Ocean surface water mass that was oceanographi­ INTRODUCTION cally distinct from the (warmer) low latitude surface waters. Significant declines in the species richness Upper Cretaceous pelagic sediments were cored of the nannofossil assemblages throughout the first by ocean drilling during the 1970's. It quickly Maastrichtian suggest progressive climatic cooling. became clear that the Upper Cretaceous calcareous Watkins, Wise, Pospichal & Crux in Microfossils and Ocean Environments, Moguilevsky & Whatley, eds. Proceedings of the "ODP and the Marine Biosphere" International Conference (Aberystwyth, Wales, April 19-21, 1994) Copyright 1996, University of Wales. Used by permission. Stratigraphy and Biostratigraphy 357 Northeast Kerguelen Naturaliste Falkland Maud Plateau Plateau Georgia Plateau Rise Rise 747 748 750 258 264 327 511 698 700 689 690 c ctl .-..... ..c () -- ........ l/l ctl ctl ~ c .-ctl C ctl a. E ctl () ? .. ~ ....~.. ..... c ~ ctl (f) ?Ps:l ~ Con. .I .. ....~.. =:=~ ~ Tu r. G- b =~=~-G c G­ I ----I .-ctl ---G -- b c fij----I ctl E 0 ? c Q) () ~ .. .. _-- G z p III 111-- debris chalk biogenic chalk and claystone flows limestone dark marl chert glauconite zeolite pyrite Fig. 2. Stratigraphic record of the Upper Cretaceous from the SOllthern high-latitude sites considered in this ."itudy. Interval,,, denoted with the symhol "b" to their right are barren of nannofossils. Watkins, Wise, Pospichal & Crux in Microfossils and Ocean Environments, Moguilevsky & Whatley, eds. Proceedings of the "ODP and the Marine Biosphere" International Conference (Aberystwyth, Wales, April 19-21, 1994) Copyright 1996, University of Wales. Used by permission. (,H (II Q(l ! !.~~. • • i .~ •i. .~ .~ . ~ •• ~ i ~ ~ i '~i ~ l" ~." •• ~ ~ .! ~. ..x ! • 1: I II I" iI i d IliJIIJI~lllltlllijli~llfil,iIIIIIIJIIIIIII~lillllk~~I~III~ljllllljli~III!lli '1:l ~ jj ~~~~~~~~UUOUOOO~~w~~~~ti~~~~~~~~~~~~~~~~O~~~~~~~~~O~~~~~~~~~~~~~~~~~~~SSS~~~NNNN ZonoI.... ...... 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