A global transition to ferruginous conditions in the early Neoproterozoic oceans

Guilbaud, Romain and Poulton, Simon W. and Butterfield, Nicholas J. and Zhu, Maoyan and Shields-Zhou, Graham A. (2015) A global transition to ferruginous conditions in the early Neoproterozoic oceans. Nature Geoscience, 8 (6). pp. 466-470. ISSN 1752-0894 EISSN:1752-0908 DOI 10.1038/ngeo2434

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Official URL: http://www.nature.com/ngeo/journal/v8/n6/full/ngeo...

Abstract

Eukaryotic life expanded during the Proterozoic eon, 2.5 to 0.542 billion years ago, against a background of fluctuating ocean chemistry. After about 1.8 billion years ago, the global ocean is thought to have been characterized by oxygenated surface waters, with anoxic and sulphidic waters in middle depths along productive continental margins and anoxic and iron-containing (ferruginous) deeper waters. The spatial extent of sulphidic waters probably varied through time, but this surface-to-deep redox structure is suggested to have persisted until the first Neoproterozoic glaciation about 717 million years ago. Here we report an analysis of ocean redox conditions throughout the Proterozoic using new and existing iron speciation and sulphur isotope data from multiple cores and outcrops. We find a global transition from sulphidic to ferruginous mid-depth waters in the earliest Neoproterozoic, coincident with the amalgamation of the supercontinent Rodinia at low latitudes. We suggest that ferruginous conditions were initiated by an increase in the oceanic influx of highly reactive iron relative to sulphate, driven by a change in weathering regime and the uptake of sulphate by extensive continental evaporites on Rodinia. We propose that this transition essentially detoxified ocean margin settings, allowing for expanded opportunities for eukaryote diversification following a prolonged evolutionary stasis before one billion years ago.

Item Type: Article
Uncontrolled Keywords: 2015AREP; IA69;
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
Journal or Publication Title: Nature Geoscience
Volume: 8
Page Range: pp. 466-470
Identification Number: 10.1038/ngeo2434
Depositing User: Sarah Humbert
Date Deposited: 13 Aug 2015 17:31
Last Modified: 25 Aug 2015 14:31
URI: http://eprints.esc.cam.ac.uk/id/eprint/3418

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