Anders Lindskog
Postdoctoral fellow
Protracted oxygenation across the Cambrian–Ordovician transition : A key initiator of the Great Ordovician Biodiversification Event?
Author
Summary, in English
Fluctuations in marine oxygen concentrations have been invoked as a primary driver for changes in biodiversity throughout Earth history. Expansions in reducing marine conditions are commonly invoked as key causal mechanisms for mass extinctions, while increases in marine oxygenation are becoming an increasingly common causal mechanism invoked for biodiversification events. Here we utilize a multiproxy approach to constrain local and global marine paleoredox conditions throughout the late Cambrian–Early Ordovician from two drill core successions in Baltoscandia. Local paleoredox proxies such as manganese concentrations and iron speciation reveal that both sites in the Baltic paleobasin had persistently anoxic and predominantly euxinic (anoxic and sulfidic) bottom water conditions throughout the study interval. Corresponding trace metal datasets indicate nuanced contraction and expansion of global anoxic and euxinic conditions along continental margins during the late Cambrian–Early Ordovician. Lastly, thallium isotope data from these locally reducing sections suggest a global expansion of oxygenated shelf and deeper marine environments from the late Cambrian into the Early Ordovician. This evidence for increasingly oxic marine environments coincides with increases in burrowing depth and tiering in marine animals, as well as diversification of body fossils throughout this ~8-million-year interval. The collective geochemical datasets provide some of the first direct paleoredox evidence for an increase in marine oxygen concentrations as a key mechanism for the Ordovician radiation of marine life.
Department/s
- Lithosphere and Biosphere Science
Publishing year
2023
Language
English
Pages
323-340
Publication/Series
Geobiology
Volume
21
Issue
3
Document type
Journal article
Publisher
Wiley-Blackwell
Topic
- Geology
Keywords
- anoxia
- biodiversity
- Cambrian
- molybdenum
- Ordovician
- thallium isotopes
- vanadium
Status
Published
ISBN/ISSN/Other
- ISSN: 1472-4677