Petrogenesis of the Dengying Formation Dolomite in Northeast Sichuan Basin,SW China:Constraints from Carbon-Oxygen Isotopic and Trace Elemental Data  

作　　者：Yuan He Wenqi Li Huichuan Liu Nansheng Qiu Kunyu Li Cheng Xi Xiaoliang Bai Hongyu Long Youlian Chen 

机构地区：[1]Research Institute of Exploration and Development of PetroChina Southwest Oil&Gasfield Company,Chengdu,610041,China [2]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing,102249,China [3]College of Geosciences,China University of Petroleum,Beijing,102249,China

出　　处：《Journal of Earth Science》2025年第1期75-88,共14页地球科学学刊(英文版)

基　　金：financially supported by the Science Foundation of China University of Petroleum,Beijing(Nos.2462018YJRC030 and 2462020YXZZ020);the China Sponsorship Council(No.202306440071)。

摘　　要：The widespread dolomite of the Sinian Dengying Formation in the Sichuan Basin(China)serves as one of the most important oil and gas reservoir rocks of the basin.Well WT1,as an exploration well,is recently drilled in the Kaijiang County,northeastern Sichuan Basin(SW China),and it drills through the Dengying Formation dolomite at the depth interval of 7500–7580 m.In this study,samples are systematically collected from the cores of that interval,followed by new analyses of carbon-oxygen isotope,major elements,trace elements,rare earth elements(REEs)and EP-MA.The Dengying Formation dolomites of Well WT1 haveδ13C values of 0.37‰to 2.91‰andδ18O values of-5.72‰to-2.73‰,indicating that the dolomitization fluid is derived from contemporary seawater in the near-surface environment,rather than the burial environment.Based on the REE patterns of EPMA-based in-situ data,we recognized the seawater-sourced components,the mixedsourced components and the terrigenous-sourced components,indicating the marine origin of the dolomite with detrital contamination and diagenetic alteration.Moreover,high Al,Th,and Zr contents indicate significant detrital contamination derived from clay and quartz minerals,and high Sr/Ba and Sr/Cu ratios imply a relatively dry depositional environment with extremely high seawater salinity,intensive evaporation,and strong influences of terrigenous sediment.

关 键 词：Sichuan Basin Dengying Formation DOLOMITE carbon-oxygen isotope EPMA 

分 类 号：P618.13[天文地球—矿床学]