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Global perturbation of the marine calcium cycle during the Permian-Triassic transition

Juan Carlos Silva-Tamayo, Kimberly V. Lau, Adam B. Jost, Jonathan L. Payne, Paul B. Wignall, Robert J. Newton, Anton Eisenhauer, Donald J. DePaolo, Shaun Brown, Kate Maher, Daniel J. Lehrmann, Demir Altiner, Yu Meiyi, Sylvain Richoz and Adina Paytan
Global perturbation of the marine calcium cycle during the Permian-Triassic transition
Geological Society of America Bulletin (January 2018) 130 (7-8): 1323-1338


A negative shift in the calcium isotopic composition of marine carbonate rocks spanning the end-Permian extinction horizon in South China has been used to argue for an ocean acidification event coincident with mass extinction. This interpretation has proven controversial, both because the excursion has not been demonstrated across multiple, widely separated localities, and because modeling results of coupled carbon and calcium isotope records illustrate that calcium cycle imbalances alone cannot account for the full magnitude of the isotope excursion. Here, we further test potential controls on the Permian-Triassic calcium isotope record by measuring calcium isotope ratios from shallow-marine carbonate successions spanning the Permian-Triassic boundary in Turkey, Italy, and Oman. All measured sections display negative shifts in delta (super 44/40) Ca of up to 0.6 ppm. Consistency in the direction, magnitude, and timing of the calcium isotope excursion across these widely separated localities implies a primary and global delta (super 44/40) Ca signature. Based on the results of a coupled box model of the geological carbon and calcium cycles, we interpret the excursion to reflect a series of consequences arising from volcanic CO (sub 2) release, including a temporary decrease in seawater delta (super 44/40) Ca due to short-lived ocean acidification and a more protracted increase in calcium isotope fractionation associated with a shift toward more primary aragonite in the sediment and, potentially, subsequently elevated carbonate saturation states caused by the persistence of elevated CO (sub 2) delivery from volcanism. Locally, changing balances between aragonite and calcite production are sufficient to account for the calcium isotope excursions, but this effect alone does not explain the globally observed negative excursion in the delta (super 13) C values of carbonate sediments and organic matter as well. Only a carbon release event and related geochemical consequences are consistent both with calcium and carbon isotope data. The carbon release scenario can also account for oxygen isotope evidence for dramatic and protracted global warming as well as paleontological evidence for the preferential extinction of marine animals most susceptible to acidification, warming, and anoxia.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 130
Serial Issue: 7-8
Title: Global perturbation of the marine calcium cycle during the Permian-Triassic transition
Affiliation: University of Houston, Department of Earth and Atmospheric Sciences, Houston, TX, United States
Pages: 1323-1338
Published: 20180125
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 85
Accession Number: 2018-032334
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Data Repository item 2018081
Illustration Description: illus. incl. geol. sketch map
N20°00'00" - N53°00'00", E74°00'00" - E135°00'00"
N36°30'00" - N47°30'00", E06°30'00" - E19°00'00"
N17°00'00" - N27°00'00", E52°30'00" - E60°00'00"
N35°49'60" - N42°00'00", E26°00'00" - E44°45'00"
Secondary Affiliation: Stanford University, USA, United StatesMassachusetts Institute of Technology, USA, United StatesUniversity of Leeds, GBR, United KingdomGEOMAR-Helmholtz Center for Ocean Research, DEU, GermanyUniversity of California at Berkeley, USA, United StatesTrinity University, USA, United StatesMiddle East Technical University, TUR, TurkeyGuizhou University, CHN, ChinaKarl-Franzens-Universitaet Graz, AUT, AustriaUniversity of California at Santa Cruz, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, 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: 201817
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