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Coupled carbon and silica cycle perturbations during the Marinoan snowball Earth deglaciation

Donald E. Penman and Alan D. Rooney
Coupled carbon and silica cycle perturbations during the Marinoan snowball Earth deglaciation
Geology (Boulder) (February 2019) 47 (4): 317-320

Abstract

The snowball Earth hypothesis proposes that if polar ice sheets were to advance equatorward of a mid-latitude threshold, runaway ice-albedo effects would lead to a stable, globally ice-covered climate state that would require extremely high atmospheric pCO (sub 2) levels (supplied by volcanic degassing over millions of years) for deglaciation. Geologic evidence, including globally distributed and low-latitude glacial deposits, suggests that two such global glaciations occurred during the Neoproterozoic. We model the coupled carbon and silica cycles through a snowball Earth event, including the extremely high pCO (sub 2) and dramatically accelerated chemical weathering of its aftermath. The enhanced delivery of dissolved weathering products to the ocean induces elevated sedimentary burial of CaCO (sub 3) (deposited as "cap carbonates") and SiO (sub 2) . Uncertainty in the relative importance of carbonate versus silicate weathering allows a wide range of possible CaCO (sub 3) burial magnitude, potentially dwarfing that of SiO (sub 2) . However, total SiO (sub 2) burial is insensitive to weathering strengths, and is set by the amount of CO (sub 2) required for deglaciation ( approximately 1019 mol). Chert associated with Marinoan post-glacial cap carbonates in Africa and Mongolia corroborate modeled predictions of elevated SiO (sub 2) burial.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 47
Serial Issue: 4
Title: Coupled carbon and silica cycle perturbations during the Marinoan snowball Earth deglaciation
Affiliation: Yale University, Department of Geology and Geophysics, New Haven, CT, United States
Pages: 317-320
Published: 20190226
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 38
Accession Number: 2019-024192
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2019107
Illustration Description: illus. incl. sect.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2019
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