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Uranium and carbon isotopes document global-ocean redox-productivity relationships linked to cooling during the Frasnian-Famennian mass extinction

Song Huyue, Song Haijun, Thomas J. Algeo, Tong Jinnan, Stephen J. Romaniello, Zhu Yuanyuan, Chu Daoliang, Gong Yiming and Ariel D. Anbar
Uranium and carbon isotopes document global-ocean redox-productivity relationships linked to cooling during the Frasnian-Famennian mass extinction
Geology (Boulder) (October 2017) 45 (10): 887-890

Abstract

The cause of the Frasnian-Famennian boundary (FFB) biotic crisis, one of the "Big Five" Phanerozoic mass extinctions, remains poorly understood. Here, we generated a high-resolution uranium-isotope profile (delta (super 238) U) for a marine carbonate section at Baisha, South China, in order to document secular variation in mean global-ocean redox conditions and to compare its relationship to coeval changes in organic carbon burial fluxes (as proxied by delta (super 13) C (sub carb) ) and global climate conditions. delta (super 238) U varied in a coordinated, mostly positive relationship with delta (super 13) C (sub carb) , indicating that expanded (reduced) oceanic anoxia was linked to lower (higher) productivity. This pattern is inconsistent with productivity control of redox conditions and suggests instead that both proxies responded to a common climatic forcing. We infer that climatic cooling (and glaciation during the Upper Kellwasser Horizon [UKH] event) led to better-ventilated oceanic conditions (higher delta (super 238) U) and greater productivity (higher delta (super 13) C (sub carb) ) owing to invigoration of global-ocean overturning circulation and enhanced upwelling. Because the UKH event coincided with the FFB mass extinction, cooling rather than oceanic anoxia may have been the main killing mechanism.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 45
Serial Issue: 10
Title: Uranium and carbon isotopes document global-ocean redox-productivity relationships linked to cooling during the Frasnian-Famennian mass extinction
Affiliation: China University of Geosciences-Wuhan, State Key Laboratory of Biogeology and Environmental Geology, Wuhan, China
Pages: 887-890
Published: 201710
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 30
Accession Number: 2018-024388
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2017292
Illustration Description: illus.
N21°30'00" - N26°19'60", E104°30'00" - E112°00'00"
Secondary Affiliation: Arizona State University, USA, United StatesWuhan Institute of Geology and Mineral Resources, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 201806
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