Climatic fluctuations and sea-surface water circulation patterns at the end of the Cretaceous era: Calcareous nannofossil evidence

摘要: Abstract New paleoecological data are presented for late Maastrichtian calcareous nannofossil assemblages of the Indian Ocean and Boreal epicontinental Chalk Sea. These compiled with recent results in tropical Atlantic, Pacific, Tethys oceans order to characterize environmental changes by end Cretaceous era. The paleobiogeographic distribution warm-water species Micula murus is updated indicates existence major sea-surface currents Atlantic similar present day. end-Maastrichtian greenhouse warming characterized at subtropical latitudes an increase abundance M. temporary disappearance high-fertility marker Biscutum constans. In realm, episode marked a contemporaneous acme Watznaueria barnesiae coincident very rare occurrences other which have never been reported before boreal latitudes. A review cyclostratigraphic Indian, points following evolution paleotemperatures last ca. 350–380 kyr Cretaceous: lasted on average little more than 200 kyr was followed 100–120 kyr cooling. Tethys, 30–40 kyr additional pulse highlighted immediately below Cretaceous–Paleogene boundary. findings indicate important instability climate system Maastrichtian, most likely caused Deccan volcanism. richness dropped during warming, may stress and/or ocean acidification. However, nannoplankton diversity returned rapidly higher values after this climatic remained high up No significant extinction recorded biotic group prior boundary clay.