Late cretaceous (Maestrichtian) calcareous nannoplankton biogeography with emphasis on events immediately preceding the cretaceous/paleocene boundary
type: CreativeWork
description: The Maestrichtian biogeography of calcareous nannoplankton is investigated in order to characterize paleoenvironmental conditions in the marine photic zone during the latest Cretaceous. Different theories explaining the biospheric turnover at the Cretaceous/Paleocene (KIP) boundary have alternatively suggested or denied substantial environmental perturbations during the last ~500 ky of the Cretaceous. The purpose of this study is to determine whether evidence from calcareous nannoplankton supports a gradual (or stepwise) decline of the photic zone environment presaging the K/P boundary. In order to achieve this goal a detailed quantitative study of the biogeography of calcareous nannoplankton was carried out in three time slices from early and late Maestrichtian. Well preserved material was investigated from five sections: Ocean Drilling Program Site 690 in the Atlantic sector of the Southern Ocean represents the Maestrichtian high southern nannoplankton province. Indian Ocean Sites 217 and 761, South Atlantic Site 528 and the land based, epicontinental section from Millers Ferry, Alabama, represent the Maestrichtian mid-/low latitudinal bioprovince. Quantitative counts were performed on settling slides under the light microscope. Occasionally scanning electron microscopy was employed to resolve taxonomic uncertainties. A pronounced turnover from early to late Maestrichtian occurred in the nannoplankton in high southern latitudes. Numerous taxa (Biscutum boletum, B. coronum, B. dissimilis, B. magnum, Misceomarginatus spp., Monomarginatus spp., Neocrepidolithus watkinsii, Nephrolithus corystus, Octocyclus magnus, Phanulithus obscurus, Psyktosphaera firthii, and Reinhardtites spp.) that are restricted to (or most abundant in) high southern latitudes became extinct in the latest early and earliest late Maestrichtian (between ~72.4 and 70.4 Ma), resulting in a loss of about one third of the early Maestrichtian nannoplankton (corresponding to ~20-25% of the assemblage). …
abstract: The Maestrichtian biogeography of calcareous nannoplankton is investigated in order to characterize paleoenvironmental conditions in the marine photic zone during the latest Cretaceous. Different theories explaining the biospheric turnover at the Cretaceous/Paleocene (KIP) boundary have alternatively suggested or denied substantial environmental perturbations during the last ~500 ky of the Cretaceous. The purpose of this study is to determine whether evidence from calcareous nannoplankton supports a gradual (or stepwise) decline of the photic zone environment presaging the K/P boundary. In order to achieve this goal a detailed quantitative study of the biogeography of calcareous nannoplankton was carried out in three time slices from early and late Maestrichtian. Well preserved material was investigated from five sections: Ocean Drilling Program Site 690 in the Atlantic sector of the Southern Ocean represents the Maestrichtian high southern nannoplankton province. Indian Ocean Sites 217 and 761, South Atlantic Site 528 and the land based, epicontinental section from Millers Ferry, Alabama, represent the Maestrichtian mid-/low latitudinal bioprovince. Quantitative counts were performed on settling slides under the light microscope. Occasionally scanning electron microscopy was employed to resolve taxonomic uncertainties. A pronounced turnover from early to late Maestrichtian occurred in the nannoplankton in high southern latitudes. Numerous taxa (Biscutum boletum, B. coronum, B. dissimilis, B. magnum, Misceomarginatus spp., Monomarginatus spp., Neocrepidolithus watkinsii, Nephrolithus corystus, Octocyclus magnus, Phanulithus obscurus, Psyktosphaera firthii, and Reinhardtites spp.) that are restricted to (or most abundant in) high southern latitudes became extinct in the latest early and earliest late Maestrichtian (between ~72.4 and 70.4 Ma), resulting in a loss of about one third of the early Maestrichtian nannoplankton (corresponding to ~20-25% of the assemblage). …
author: Ehrendorfer, Thomas W.
language: en_US
keywords: Plankton, Micropaleontology, Paleontology, Fossil
date published: 1993-02
date modified: 2026-07-27T22:05:12Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/5508

PropertyValue
property ID: DOI
value: 10.1575/1912/5508