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Selective extinction of marine plankton in the Paratethys at the end of the Mesozoic Era; a multiple interaction hypothesis

Yvonne Herman
Selective extinction of marine plankton in the Paratethys at the end of the Mesozoic Era; a multiple interaction hypothesis (in Global catastrophes in Earth history; an interdisciplinary conference on impacts, volcanism, and mass mortality, Virgil L. Sharpton (editor) and Peter D. Ward (editor))
Special Paper - Geological Society of America (1990) 247: 531-540

Abstract

Floral, faunal, and stable isotope evidence in a continuous sequence of latest Cretaceous and earliest Tertiary shallow-water marine carbonates in the Mangyshlak Peninsula, northeast of the Caspian Sea, USSR, suggest severe environmental changes at the Cretaceous/Tertiary (K/T) boundary. Time frame is provided by nanno-, micro-, and macrofossils as well as by magnetic stratigraphy and an iridium spike. Oxygen-isotopic analyses of the bulk sediments, composed of nanno- and micro-plankton skeletal remains, show a sharp positive spike from -4.2 per mil to -1.2 per mil at the K/T boundary. Since the sediments have undergone diagenesis, a process that results in depletion of oxygen 18, the positive spike at the boundary was attenuated by diagenesis and represents a minimum value. This shift is primarily attributed to abrupt and severe cooling, possibly accompanied by increased salinities of the surface mixed layer. A reversal in the delta (super 18) O signal from -1.2 per mil to -4.6 per mil at 1 mm above the boundary is interpreted to be indicative of marked warming and decreased salinities. The echinoids and benthonic foraminifera exhibit a modest shift in delta (super 18) O, suggesting much less pronounced temperature and salinity changes of the bottom water. Independent geological evidence indicates that the terminal Cretaceous temperature decline was coeval with widespread and intense volcanism, which peaked at the close of the Mesozoic Era. It is proposed that volatile emissions from massive volcanic eruptions led to acid rain, which depressed the surface-water pH, temporarily prohibiting calcite nucleation of the surface-dwelling warm-water plankton. Superimposed upon severe and rapid climatic changes, decreased alkalinity caused the extinction of calcareous phyto- and zooplankton. The extinction appears to have extended over several hundred thousand years.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 247
Title: Selective extinction of marine plankton in the Paratethys at the end of the Mesozoic Era; a multiple interaction hypothesis
Title: Global catastrophes in Earth history; an interdisciplinary conference on impacts, volcanism, and mass mortality
Author(s): Herman, Yvonne
Author(s): Sharpton, Virgil L.editor
Author(s): Ward, Peter D.editor
Affiliation: Wash. State Univ., Dep. Geol., Pullman, WA, United States
Affiliation: Lunar and Planet. Inst., Houston, TX, United States
Pages: 531-540
Published: 1990
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Meeting name: Global catastrophes in Earth history; an interdisciplinary conference on impacts, volcanism, and mass mortality
Meeting location: Snowbird, UT, USA, United States
Meeting date: 19881020Oct. 20-23, 1988
References: 50
Accession Number: 1995-026176
Categories: Stratigraphy
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sects.
N42°30'00" - N45°00'00", E50°00'00" - E54°30'00"
N36°00'00" - N82°00'00", W170°00'00" - E20°00'00"
Secondary Affiliation: Univ. Wash., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199510
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