Coupled measurements of δ^18O and δD of hydration water and salinity of fluid inclusions in gypsum from the Messinian Yesares Member, Sorbas Basin (SE Spain)

Evans, Nicholas P. and Turchyn, Alexandra V. and Gázquez, Fernando and Bontognali, Tomaso and Chapman, Hazel J. and Hodell, David A. (2015) Coupled measurements of δ^18O and δD of hydration water and salinity of fluid inclusions in gypsum from the Messinian Yesares Member, Sorbas Basin (SE Spain). Earth and Planetary Science Letters, 430. pp. 499-510. ISSN 0012-821X DOI 10.1016/j.epsl.2015.07.071

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Abstract

We studied one cycle (Cycle 6) of gypsum–marl deposition from the Messinian Yesares Member in Sorbas Basin, Spain. The objective was to reconstruct the changing environment of deposition and its relation to astronomically-forced climate change. The δ18O and δD of gypsum hydration water (CaSO4 • 2H2O) and salinity of fluid inclusions were measured in the same samples to test if they record the composition of the mother fluid from which gypsum was precipitated. Water isotopes are highly correlated with fluid inclusion salinity suggesting the hydration water has not exchanged after formation. The relatively low water isotope values and fluid inclusion salinities indicate a significant influence of meteoric water, whereas δ34S, δ18OSO4 and 87Sr/86Sr support a dominant marine origin for the gypsum deposits. The discrepancy between water and elemental isotope signatures can be reconciled if meteoric water dissolved previously deposited marine sulfates supplying calcium and sulfate ions to the basin which maintained gypsum saturation. This recycling process accounts for the marine δ34S, δ18OSO4 and 87Sr/86Sr signatures, whereas the low δ18O and δD values of gypsum hydration water and fluid inclusion salinities reflect the influence of freshwater.

Item Type:	Article
Uncontrolled Keywords:	2015AREP; IA69; published
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems 06 - Part-III Projects 07 - Gold Open Access
Journal or Publication Title:	Earth and Planetary Science Letters
Volume:	430
Page Range:	pp. 499-510
Identification Number:	10.1016/j.epsl.2015.07.071
Depositing User:	Sarah Humbert
Date Deposited:	25 Aug 2015 16:29
Last Modified:	29 Sep 2015 15:47
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3479

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