Toggle Main Menu Toggle Search

Open Access padlockePrints

Pervasive oxygenation along late Archaean ocean margins

Lookup NU author(s): Professor Simon Poulton

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

The photosynthetic production of oxygen in the oceans is thought to have begun by 2.7 billion years ago, several hundred million years before appreciable accumulation of oxygen in the atmosphere. However, the abundance and distribution of dissolved oxygen in the late Archaean oceans is poorly constrained. Here we present geochemical profiles from 2.6- to 2.5-billion-year-old black shales from the Campbellrand-Malmani carbonate platform in South Africa. We find a high abundance of rhenium and a low abundance of molybdenum, which, together with the speciation of sedimentary iron, points to the presence of dissolved oxygen in the bottom waters on the platform slope. The water depth on the slope probably reached several hundred metres, implying the export of O-2 below the photic zone. Our data also indicate that the mildly oxygenated surface ocean gave way to an anoxic deep ocean. We therefore suggest that the production of oxygen in the surface ocean was vigorous at this time, but was not sufficient to fully consume the deep-sea reductants. On the basis of our results and observations from the Hamersley basin in Western Australia, we conclude that the productive regions along ocean margins during the late Archaean eon were sites of substantial O-2 accumulation, at least 100 million years before the first significant increase in atmospheric O-2 concentration.


Publication metadata

Author(s): Kendall B, Reinhard CT, Lyons T, Kaufman AJ, Poulton S, Anbar AD

Publication type: Article

Publication status: Published

Journal: Nature Geoscience

Year: 2010

Volume: 3

Issue: 9

Pages: 647-652

Print publication date: 01/09/2010

ISSN (print): 1752-0894

ISSN (electronic): 1752-0908

Publisher: Nature Publishing Group

URL: http://dx.doi.org/10.1038/NGEO942

DOI: 10.1038/NGEO942


Altmetrics

Altmetrics provided by Altmetric


Share