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MPC-01 General contributions to geochronology and isotope geology
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δ34S, δ18O, 87Sr/86Sr of Celestine Deposits from Tertiary Sivas Basin, Turkey
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Ali Ucurum, Cumhuriyet University (Turkey)
Osman Koptagel, Cumhuriyet University (Turkey)
Ahmet Efe, Cumhuriyet University (Turkey)
Cigdem Sahin, Cumhuriyet University (Turkey)
Greg, B Arehart, University of Nevada Reno (United States)
Paul J. Lechler, University of Nevada Reno (United States)
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Sulphur (δ34S), oxygen (δ18O) and strontium (87Sr/86Sr) isotope ratios have been measured in 50 celestine mineral separates from 13 different Tertiary celestine deposits located in Sivas, central-east Anatolia, Turkey. Celestine has been classified as vuggy filling in Eocene shallow shelf-lagoon; nodular in Oligocene coastal sabkha-alluvial; and massive in Miocene shallow lagoon environments. All of these deposits are associated with evaporites, including gypsum and anhydrite. Sulphur, oxygen and strontium isotope data have been used to determine the origin of dissolved sulphate in the brines that precipitated celestine minerals. Relationships between 18O/16O-δ34S and 87Sr/86Sr-δ34S shows that only three of the Eocene deposits have signatures of marine evaporites and all others plot outside the marine evaporite box.
δ34S, δ18O values and 87Sr/86Sr ratio of celestine minerals range between 21-40‰; 15-26‰; 0.70558-0.70791 respectively. High δ34S values of celestine indicate that the dissolved sulphur in basinal brines had undergone partial reduction to sulphide, probably in a restricted non oceanic environment. Lower 87Sr/86Sr ratios of celestine minerals compared to average Cenozoic sea water (~ 0.7091) suggest that interstratal brines may have mixed with other circulating fluids (meteoric hydrothermal) that had interacted with local volcanoclastic sediments ? which are intercalated with evaporates ? and had undergone Sr isotope exchange. Oxygen isotope data are consistent with derivation primarily from seawater or a combination of seawater and meteoric-hydrothermal fluids.
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