The preservation of d34sSO4 and d18OSO4 in carbonate-associated sulfate during marine diagenesis: a 25 Myr test case using marine sediments

Rennie, Victoria and Turchyn, Alexandra V. (2014) The preservation of d34sSO4 and d18OSO4 in carbonate-associated sulfate during marine diagenesis: a 25 Myr test case using marine sediments. Earth and Planetary Science Letters, 395. pp. 13-23. ISSN 0012-821X DOI 10.1016/j.epsl.2014.03.025

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Abstract

A 25 million year record of the sulfur and oxygen isotope composition of marine carbonate-associated sulfate (CAS) was constructed from 55 nannofossil ooze samples at three different locations. We tested the impact of early marine diagenesis on CAS by comparing the CAS extractions to the sulfur and oxygen isotope composition of the associated pore fluid sulfate, to determine the degree of pore fluid incorporation during carbonate recrystallization. Neither the sulfur nor the oxygen isotope composition of CAS are completely overprinted by incorporation of pore fluid sulfate. We compare our record to the sulfur and oxygen isotope records of coeval barite. The sulfur isotope record is in agreement with the barite record within ±2‰±2‰, except where very young (<2 Ma) sediments are in the presence of highly evolved pore fluid sulfate (View the MathML sourceδS34=70‰). A simple recrystallization model is used to illustrate the sensitivity of CAS View the MathML sourceδSSO434 to sedimentation rate, and to emphasize that careful sample selection, along with an analysis of early diagenetic environmental conditions is crucial when interpreting CAS sulfur isotopes. Oxygen isotopes in CAS are more complex and do not reproduce similar values to those of coeval barite. We conclude that oxygen isotopes in sulfate may remain a useful proxy but merit closer attention in the future.

Item Type: Article
Additional Information: Copyright © 2014 The Authors.
Uncontrolled Keywords: 2014AREP; IA67; Phd, gd OA,
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
07 - Gold Open Access
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 395
Page Range: pp. 13-23
Identification Number: 10.1016/j.epsl.2014.03.025
Depositing User: Sarah Humbert
Date Deposited: 04 Apr 2014 15:18
Last Modified: 13 Jul 2014 16:43
URI: http://eprints.esc.cam.ac.uk/id/eprint/3003

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