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A sink- or a source-driven carbon cycle at the geological time scale? Relative importance of palaeogeography versus solid earth degassing rate in the Phanerozoic climatic evolution

Yves Godderis and Yannick Donnadieu
A sink- or a source-driven carbon cycle at the geological time scale? Relative importance of palaeogeography versus solid earth degassing rate in the Phanerozoic climatic evolution (in Advances in paleogeography, G. Meinhold (prefacer))
Geological Magazine (February 2019) 156 (2): 355-365

Abstract

The Phanerozoic evolution of the atmospheric CO (sub 2) level is controlled by the fluxes entering or leaving the exospheric system. In this contribution, we focus on the role played by the palaeogeographic configuration on the efficiency of the CO (sub 2) sink by continental silicate weathering, and on the impact of the magmatic degassing of CO (sub 2) . We use the spatially resolved numerical model GEOCLIM to compute the response of the silicate weathering and atmospheric CO (sub 2) to continental drift for 22 time slices of the Phanerozoic. Regarding the CO (sub 2) released by the magmatic activity, we reconstruct several Phanerozoic histories of this flux, based on published indices. Again using the GEOCLIM model, we calculate the CO (sub 2) evolution for each degassing scenario. We show that the palaeogeographic setting is a main driver of the climate from 540 Ma to about the beginning of the Jurassic, with the noticeable exception of the Late Palaeozoic ice age. Regarding the role of the magmatic degassing, the various reconstructions do not converge towards a single signal, and thus introduce large uncertainties in the calculated CO (sub 2) level over time. Nevertheless, the continental dispersion, which prevails since the Jurassic, promotes CO (sub 2) consumption by weathering and forces atmospheric CO (sub 2) to stay low. Warm climates of the "middle" Cretaceous and early Cenozoic require enhanced CO (sub 2) degassing by magmatic activity.


ISSN: 0016-7568
EISSN: 1469-5081
Coden: GEMGA4
Serial Title: Geological Magazine
Serial Volume: 156
Serial Issue: 2
Title: A sink- or a source-driven carbon cycle at the geological time scale? Relative importance of palaeogeography versus solid earth degassing rate in the Phanerozoic climatic evolution
Title: Advances in paleogeography
Author(s): Godderis, YvesDonnadieu, Yannick
Author(s): Meinhold, G.prefacer
Affiliation: Geosciences Environnement Toulouse, Toulouse, France
Affiliation: Keele University, Keele, United Kingdom
Pages: 355-365
Published: 201902
Text Language: English
Publisher: Cambridge University Press, London, United Kingdom
References: 44
Accession Number: 2019-021274
Categories: General geochemistryStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: European Centre for Research and Teaching in Environmental Geosciences, FRA, France
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Cambridge University Press. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201913
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