Planktonic foraminiferal biostratigraphy and mechanisms in the extinction of Morozovella in the late middle Eocene

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doi: 10.1016/j.marmicro.2003.09.001
Author(s): Wade, Bridget S.
Author Affiliation(s): Primary:
University of Edinburgh, Institute of Earth Sciences, Edinburgh, United Kingdom
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 51(1-2), p.23-38. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. 81 refs.; illus., incl. 1 plate, 1 table, sketch map
Summary: The muricate planktonic foraminiferal genera Morozovella and Acarinina were abundant and diverse during the upper Palaeocene to middle Eocene and dominated the tropical and subtropical assemblages. A significant biotic turnover in planktonic foraminifera occurred in the latest middle Eocene with a notable reduction in the acarininid lineage and the extinction of the morozovellids. These genera are extensively employed as palaeoclimatic and biostratigraphic markers and, therefore, this turnover episode is an important event in the record of the Cenozoic planktonic foraminifera. Sediments from the western North Atlantic (Ocean Drilling Program Site 1052) were examined in order to investigate these extinction events, in terms of both timing and mechanisms. Biostratigraphic events of the middle and late Eocene have been examined with a sampling resolution of approximately 3 kyr. These have been calibrated to the magneto- and astrochronology to accurately define the timing of key biostratigraphic events, particularly the extinction of Morozovella spinulosa which is a distinct biomarker for late middle Eocene sediments. High-resolution biostratigraphy reveals that the extinctions in the muricate group occurred in a stepwise form. The large acarininids (Acarinina praetopilensis) terminate 10 kyr prior to the extinction of M. spinulosa and small acarininids (Acarinina medizzai and Acarinina echinata) continue into the upper Eocene. High-resolution stable isotope analyses have been conducted on planktonic and benthic foraminifera from the western North Atlantic to reconstruct sea surface temperatures (SSTs) and deep water temperatures and the structure of the water column around this major biotic turnover. Whilst the extinctions of M. spinulosa and A. praetopilensis occur during a long-term cooling trend, the biotic turnover in the muricate group does not appear to be related to significant climatic change. Sea surface temperatures decrease slowly prior to the extinction events, and there is no evidence for a large-temperature shift associated with the faunal changes. The turnover event was therefore probably related to the increased surface water productivity and the deterioration of photosymbiotic partnerships with algae. Abstract Copyright (2004) Elsevier, B.V.
Year of Publication: 2004
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Acarinina; Atlantic Ocean; Biostratigraphy; Blake Nose; Blake Plateau; C-13/C-12; Carbon; Cenozoic; Eocene; Extinction; Foraminifera; Invertebrata; Isotope ratios; Isotopes; Leg 171B; Marine environment; Microfossils; Middle Eocene; Morozovella spinulosa; North Atlantic; O-18/O-16; ODP Site 1052; ODP Site 1053; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleoecology; Paleoenvironment; Paleogene; Paleotemperature; Planktonic taxa; Protista; SEM data; Stable isotopes; Tertiary
Coordinates: N295700 N295900 W0763100 W0763700
Record ID: 2005071294
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands