論文

査読有り
2018年7月1日

Sulfur, strontium, carbon, and oxygen isotopes of calcium sulfate deposits in late carboniferous rocks of the loei-wang saphung (LWS) area, Loei province, Thailand

Geosciences (Switzerland)
  • Nusara Surakotra
  • ,
  • Sarunya Promkotra
  • ,
  • Punya Charusiri
  • ,
  • Teruyuki Maruoka
  • ,
  • Ken-Inchiro Hisada

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記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.3390/geosciences8070229
出版者・発行元
MDPI AG

Sulfate deposits of the Loei-Wang Saphung (LWS) area, northeastern Thailand, intercalated with carbonate and silicic clastic rock were analyzed for S, O, C, and Sr to determine the depositional environment, as well as the age of formation. Sulfate samples yielded average values of δ34S of 14.6‰, while the87Sr/86Sr ratio of gypsum was 0.708282 and that of anhydrite was 0.708288. The carbonate layers yielded average δ18OPDB, and δ13C values of −12.5‰ and −0.1‰, respectively. Our results revealed that the LWS evaporite deposits were originally formed from seawater, and the relatively negative value of δ18O was a result of meteoric alteration during subaerial exposure of the sections. Comparing these isotopic values with the nearby Nakon Sawan sulfate deposits, the Sr isotopes showed slightly higher values with very mild variations. These isotopic values suggest that the LWS deposits were not affected by subsequent hydrothermal alteration by younger igneous dikes in this area. Therefore, some of these isotope signatures are considered to be primary features of the deposit, despite the fact that the deposit underwent anchizone to epizone metamorphism. The S and Sr isotope values support the depositional age of the LWS sulfate deposit in the Middle to Late Carboniferous.

リンク情報
DOI
https://doi.org/10.3390/geosciences8070229

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