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Linking the progressive expansion of reducing conditions to a stepwise mass extinction event in the late Silurian oceans

Author:
  • Chelsie N. Bowman
  • Seth A. Young
  • Dimitri Kaljo
  • Mats E. Eriksson
  • Theodore R. Them
  • Olle Hints
  • Tõnu Martma
  • Jeremy D. Owens
Publishing year: 2019
Language: English
Pages: 968-972
Publication/Series: Geology
Volume: 47
Issue: 10
Document type: Journal article
Publisher: Geological Society of America

Abstract english

The late Ludlow Lau Event was a severe biotic crisis in the Silurian, characterized by resurgent microbial facies and faunal turnover rates otherwise only documented during the "big five" mass extinctions. This asynchronous late Silurian marine extinction event preceded an associated positive carbon isotope excursion (CIE), the Lau CIE, although a mechanism for this temporal offset remains poorly constrained. Here, we report thallium isotope data from locally reducing late Ludlow strata within the Baltic Basin to document the earliest onset of global marine deoxygenation. The initial expansion of anoxia coincided with the onset of the extinction and therefore preceded the Lau CIE. Additionally, sulfur isotope data record a large positive excursion parallel to the Lau CIE, interpreted to indicate an increase in pyrite burial associated with the widely documented CIE. This suggests a possible global expansion of euxinia (anoxic and sulfidic water column) following deoxygenation. These data are the most direct proxy evidence of paleoredox conditions linking the known extinction to the Lau CIE through the progressive expansion of anoxia, and most likely euxinia, across portions of the late Silurian oceans.

Keywords

  • Geology

Other

Published
  • ISSN: 0091-7613
Mats Eriksson
E-mail: mats [dot] eriksson [at] geol [dot] lu [dot] se

Professor

Lithosphere and Biosphere Science

+46 46 222 96 02

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