Quantitative determination constraints on dolomitization model for the Upper Permian Changxing reservoir dolomites of Northeastern Sichuan Basin, Southwestern China

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• 作者：Rui Zhao ; Ya Sheng Wu ; Hong Xia Jiang ; Qing Song Liu…
• 刊名：Carbonates and Evaporites
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：31
• 期：3
• 页码：289-305
• 全文大小：4,138 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geology
  Earth sciences
  Mineral Resources
  Mineralogy
  
• 出版者：Springer Berlin Heidelberg
• ISSN：1878-5212
• 卷排序：31

文摘

Natural gas was found in Upper Permian Changxing dolomite reservoirs of the NE Sichuan Basin, China. Researching the mechanisms for dolomitization was essential for petroleum exploration. Outcrop samples from Upper Permian Changhsingian Panlongdong and Yanggudong sections were studied using statistical work, cathodoluminescence (CL), electron microprobe, major element analysis and isotope studies (δ18O and δ13C), in an attempt to determine the migration pathway and origin of the dolomitizing fluids. The dolomite content, average dolomite size, δ18O values and Mg/Ca ratios were all decreased downwardly in the two sections, indicating that the Changxing dolomitizing fluid migrated downwardly from the top of Changxing Formation (sediments). The Mg, Na, Fe, Mn and Sr elements were uniformly distributed in dolomite crystals which proved that the dolomites were formed in the same fluid without time interval. The element content in Changxing dolomites was similar to that of the Feixiangan sakbha dolomites and the δ18O values of Changxing dolomite were much higher than those of the Changxing limestone, which suggested that the dolomitizing fluid was originated from evaporative seawater. In conclusion, we concluded that the coeval Changhsingian evaporative seawater caused dolomitization.KeywordsUpper PermianSichuan BasinDolomiteDolomitizing fluidDolomitization