Calcareous nannofossil biogeography illustrates palaeoclimate change in the Late Cretaceous Indian Ocean

• Published in: Cretaceous research Vol. 23; no. 5; pp. 537 - 634
• Main Author: Lees, Jackie A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2002
• Subjects: biostratigraphy; calcareous nannofossils; correlation; Late Cretaceous; palaeobiogeography; palaeoclimate; palaeoecology; correlation; palaeoclimate; palaeobiogeography; biostratigraphy; calcareous nannofossils; Late Cretaceous; palaeoecology
• ISSN: 0195-6671; 1095-998X
• DOI: 10.1006/cres.2003.1021

Late Cretaceous calcareous nannofossil taxa, their distributions and relative abundances were recorded from nine Indian Ocean sites. The majority of taxa are shown to be broadly cosmopolitan, although a significant proportion shows some degree of biogeographical restriction. Effective, high-resolution biostratigraphy is dependent upon a better understanding of biogeography. In order to understand better the manifestation of nannofossil palaeobiogeography in the Late Cretaceous, palaeobiogeographical zones were plotted for the Indian Ocean, at 5-my intervals. These zones (Subantarctic, Austral, Temperate, Tropical) were defined using a combination of taxa that displayed high relative abundances, and those that were not highly-abundant but which appeared to be geographically restricted. The extent of the palaeobiogeographical zones was observed to change with time. This pattern is interpreted in terms of climate change. This change, as predicted by the nannofossils, is in strong agreement with recent isotopic evidence for the region: general late Albian–late Cenomanian cooling, late Cenomanian–late Turonian warming, late Turonian–latest Maastrichtian cooling, with mid-Campanian? and late Maastrichtian warming pulses, and a late Campanian–early Maastrichtian cooling event. The use of nannofossils as proxies for palaeoclimate and palaeoclimate change is discussed. Palaeoecological profiles for all of the taxa encountered are presented. Ninety taxa are postulated as having r-selected tendencies, with respect to ecological strategy.