Carbon sequestration in an expanding lake system during the Toarcian Oceanic Anoxic Event
Nature Publishing Group
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The Early Jurassic Toarcian Oceanic Anoxic Event (~183 Ma) was marked by marine anoxia–euxinia and globally significant organic-matter burial, accompanied by a major global carbon-cycle perturbation probably linked to Karoo-Ferrar volcanism. Although the Toarcian Oceanic Anoxic Event is well studied in the marine realm, accompanying climatic and environmental change on the continents is poorly understood. Here, utilizing radiometric, palynological and geochemical data from lacustrine black shales, we demonstrate that a major lake system developed contemporaneously with the Toarcian Oceanic Anoxic Event in the Sichuan Basin, China, likely due to enhanced hydrological cycling under elevated atmospheric pCO2. Coeval accelerated organic-carbon burial in both marine and lacustrine basins suggests nutrient delivery as the prime cause for global carbon-cycle recovery during the Toarcian Oceanic Anoxic Event. Increased lacustrine organic productivity from elevated fluvial nutrient supply resulted in the burial of ~460 Gt of organic carbon in the Sichuan Basin alone, creating an important negative feedback in the global exogenic carbon cycle, which significantly shortened the global δ13C recovery
Shell International Exploration & Production B.V. is acknowledged for financial support for this study. D.S. acknowledges the Total endowment fund. R.D.P. and B.D.A.N. acknowledge funding from the advanced ERC grant “the greenhouse earth system” (T-GRES, project reference 340923).
Shell International Exploration & Production B.V. is acknowledged for financial support for this study. D.S. acknowledges the Total endowment fund. R.D.P. and B.D.A.N. acknowledge funding from the advanced ERC grant ‘the greenhouse earth system’ (T-GRES, project reference 340923). All authors thank Shell Global Solutions International B.V., Shell China Exploration & Production Co. Ltd, and PetroChina Southwest Oil and Gasfield Company for approval to publish this study. J.B.R. publishes with the approval of the Executive Director, British Geological Survey (NERC). CGG Robertson and Shell are acknowledged for providing the palaeogeographic reconstruction used in Fig. 1. T.-R. Jiang, M. Dransfield and X.-Y. Li (Shell China Exploration and Production Co. Ltd), O. Podlaha, S. v. d. Boorn (Shell Global Solutions International B.V.), Q. Zeng and Z. Tang (PetroChina Southwest Oil and Gasfield Company) and B. Levell (University of Oxford) are acknowledged for discussions and reviews of earlier versions of the manuscript and for providing sample materials. We also thank reviewers D. Kemp and G. Suan for comments and suggestions that have greatly improved this manuscript. This paper is also a contribution to UNESCO-IUGS IGCP Project 632.
This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.
Published online 16 January 2017