Geochemical characteristics and fluid origin of the Dengying Formation dolomites in southern Sichuan Basin

被引：0

作者：

Wu T. ^{[1
]}

Xie S. ^{[1
]}

Zhang D. ^{[2
]}

Li P. ^{[1
]}

Bao Z. ^{[1
]}

He Z. ^{[2
]}

Qian Y. ^{[2
]}

Jiao C. ^{[2
]}

机构：

[1] Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, Hubei

[2] Exploration & Production Research Institute, SINOPEC, Beijing

来源：

Oil and Gas Geology | 2016年 / 37卷 / 05期

关键词：

Dengying Formation; Dolomite; Fluid origin; Geochemical characteristics; Sichuan Basin;

D O I：

10.11743/ogg20160512

中图分类号：

学科分类号：

摘要：

Dolomite of the Dengying Formation in southern Sichuan Basin has been studied a lot as an important kind of reservoir rocks for oil and gas.However,origin of the dolomite is still in controversy.This paper studied the geochemical characteristics and fluid origin of the dolomite in the Dengying Formation in southern Sichuan Basin through analyses of C-O isotopes and trace elements.The results show that the main types of dolomites are micritic dolomite,fine-medium dolomite and breccia-dolomite.The δ13C and δ18O values are 0.52‰~2.06‰ (PDB) and -11.9‰~-2.14‰ (PDB),respectively,which are lower than the original values of δ13C (4.43‰) and δ18O (-0.62‰) of carbonates of the same period.The dolomite has high U/Th ratio,low Sr and high Eu anomalies.It is believed that the dolomite formed in a burial diagenetic environment and was altered by hydrothermal fluid later.REE distribution patterns of the dolomite is similar to the dolomite originated from seawater.Salinity indexes(Z)of the dolomite is higher than those of normal seawater.Therefore,it can be inferred that the dolomitization fluids mainly originate from the condensed seawater trapped in the Formation. © 2016, Editorial Office of Oil and Gas Geology. All right reserved.

引用

页码：721 / 730

页数：9

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