Late Cretaceous (Maestrichtian) Calcareous Nannoplankton Biogeography with Emphasis on Events Immediately Preceding the Cretaceous/Paleocene Boundary

Well preserved late Cretaceous (Maestrichtian) nannoplankton assemblages from high southern and mid-latitudes were investigated to delineate paleoenvironmental conditions in the marine photic zone prior to the Cretaceous/ Paleocene boundary. A pronounced turnover from early to late Maestrichtian occ...

Full description

Bibliographic Details
Main Author: Ehrendorfer, Thomas W.
Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
Format: Text
Language:English
Published: 1993
Subjects:
Biological Oceanography
Geology
Geochemistry and Mineralogy
*GEOLOGY
*PLANKTON
TIME INTERVALS
TEMPERATURE
GLOBAL
SURFACE WATERS
OCEANS
INDIAN OCEAN
MESOZOIC ERA
LATITUDE
HIGH LATITUDES
PATTERNS
BOUNDARIES
WATER
COOLING
*CRETACEOUS/PALEOCENE BOUNDARY
*NANNOPLANKTON
Indian
Southern Ocean
Online Access:http://www.dtic.mil/docs/citations/ADA269169
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA269169
Description
Summary:Well preserved late Cretaceous (Maestrichtian) nannoplankton assemblages from high southern and mid-latitudes were investigated to delineate paleoenvironmental conditions in the marine photic zone prior to the Cretaceous/ Paleocene boundary. A pronounced turnover from early to late Maestrichtian occurred in high southern latitudes with about one third of the early Maestrichtian nannoplankton species becoming extinct around the early/late Maestrichtian boundary (-72.4-70.4 Ma). These extinctions are not a consequence of temperature decrease alone but also of increased surface water fertility. Another third of all species disappeared from high southern latitudes during the same time interval but persisted until the end of the Maestrichtian at lower latitudes. This is by the isotopic record. Abundance increases of certain high latitude taxa (e.g. Nephrolithus frequens, Cribrosphaerella? daniae, Kamptnerius magnificus, and Gartnerago spp.) in the Southern Ocean correlate roughly with decreasing temperature while abundance changes of others (e.g. Ahmuellerella octoradiata) do not, indicating that latitudinal biogeographic patterns do not necessarily reflect temperature differences. During the last 500 ky of the Maestrichtian high abundance fluctuations occurred in a few taxa in the South Atlantic and Southern Oceans. However, no such fluctuations seem to have occurred during the same time in the Indian Ocean. There is no evidence for gradual or stepwise extinctions of nannoplankton during the late Maestrichtian.

Similar Items