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Geoscience ›› 2020, Vol. 34 ›› Issue (01): 74-87.DOI: 10.19657/j.geoscience.1000-8527.2020.004

• Petrology • Previous Articles     Next Articles

Geochemical Features and Genesis of Dolomite in Sinian Dengying Formation of Zigui Area, Hubei Province

MA Jiayi1(), XIE Shuyun1(), ZHANG Mohai1, JIAO Cunli2, HAN Jun3, BAO Zhengyu1, WU Tie4, ZHANG Hai5   

  1. 1. School of Earth Sciences, China University of Geosciences, Wuhan,Hubei 430074, China
    2. Research Institute of Exploration & Production, SINOPEC, Beijing 100083, China
    3. SINOPEC Northwest Company, Urumqi, Xinjiang 830011, China
    4. Guangdong Nonferrous Metals Engineering Investigation Design Institute, Guangzhou,Guangdong 510300, China
    5. No.113 Geological Team,Guizhou Bureau of Geology & Mineral Resources,Liupanshui,Guizhou 550001, China
  • Received:2018-10-13 Revised:2019-07-10 Online:2020-03-05 Published:2020-03-07
  • Contact: XIE Shuyun

Abstract:

Fluid properties of dolomitization and dolomite diagenesis is a hotspot of carbonate diagenesis research in recent years. It is very important to study the genesis of dolomite and to understand the formation mechanism of dolomite reservoirs, which can be used to predict high-quality reservoirs. In this paper, the genesis of dolomites in Dengying Formation in Zigui County has been studied systematically via petrological, mineralogical (X-ray diffraction), and geochemical (trace elements, REEs and carbon-oxygen isotopes) analyses, and possible dolomitization patterns were inferred. According to the trace element characteristics, the Zigui dolomites had not been affected by terrigenous debris, and were formed in an arid, highly-saline seawater and oxidizing environment. The Sr contents show that the dolomites have been completely dolomitized, and the diagenetic environment was likely a high-temperature burial one with no effect of syn-diagenetic leaching. The dolomitized fluids were mainly derived from seawater. Based on the results above, we proposed the evaporite dolomite (Sabuha) and burial dolomitization models to account for the formation of mud microcrystalline dolomite and crystalline dolomite in Zigui area.

Key words: Dengying Formation, geochemistry, dolomite, diagenetic model, Zigui area

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