Calcareous nannofossil biostratigraphy and turnover dynamics in the late Campanian-Maastrichtian of the tropical South Atlantic

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• 作者：Nicolas Thibault ^{nt@ign.ku.dk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Calcareous nannofossils ; Evolutionary dynamics ; Biostratigraphy ; Late Campanian&ndash ; Maastrichtian
• 刊名：Revue de Micropaleontologie
• 出版年：2016
• 出版时间：January-March 2016
• 年：2016
• 卷：59
• 期：1
• 页码：57-69
• 全文大小：4818 K

文摘

The complete late Campanian–Maastrichtian succession of the South Atlantic reference DSDP Site 525A has been investigated to establish a detailed record of calcareous nannofossil biohorizons. A complete holostratigraphy of the core is presented for this interval and allows for global correlations to other Tethyan and Boreal reference sections for that interval. The new study allows for proposing a new time scale with a tie of Tethyan and Boreal nannofossil zonations. A new subzonation is proposed for the late Campanian UC16 Zone in the Tethyan Realm and the last occurrences of Uniplanarius trifidus and Zeugrhabdotus praesigmoides are demonstrated as markers of the Campanian–Maastrichtian boundary. The difference between cumulative first and last occurrences reflects the turnover dynamics of calcareous nanoplankton in the South Atlantic and highlights 6 major events. Five of them appear well related to major changes in sea-surface temperatures whereas the sixth event is likely the expression of a global decrease in primary productivity in the late Maastrichtian. Surprisingly, the turnover dynamics in calcareous nannoplankton appears completely unrelated to that observed in planktic foraminifera which shows only 4 major events with different timings. The two groups thus seem to have responded either very differently to similar environmental constraints or to different direct environmental constraints in the photic zone, although caused by the same global changes in climate.