Distribution Patterns of Calcite Cement in the Turbidite Sandstones of the Shahejie Formation in the Dongying Depression,Eastern China  

作　　者：ZHANG Yongwang QU Zhengyang 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China [2]College of Geosciences,China University of Petroleum-Beijing,Beijing 102249,China [3]No.4 Oil Production Plant,PetroChina Changqing Oilfield Company,Yinchuan 718500,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第3期1041-1056,共16页地质学报（英文版）

基　　金：funded by the National Natural Science Foundation of China (Grant No. 41572113)

摘　　要：Calcite cements are volumetrically dominant among the most diagenetic constituents in turbidite sandstones of the Paleogene Shahejie Formation in the Dongying Depression.The results show carbonate cements mainly occur in three phases:Calcite I(pre-compaction),Calcite II(post-compaction)and ankerite in the turbidite sandstone.The isotopic composition of Calcite I and Calcite II range from−4.3‰to 4.4‰,−3.5‰to 4.3‰PDB,respectively,suggesting that the calcite cements are mainly derived from the interbedded shales.The early calcite cement precipitated from the mixing of lacustrine and meteoric waters at 38-69℃.The late-phase calcite precipitated from pore waters modified by water-rock interactions at 64-126℃.Two distribution patterns of calcite cements can be identified,depending on their position within the sandstone.The peripheral cementation of the sandstones is near the sand-shale contact.The development of cement is controlled by sandstone thickness and the properties of the interbedded shale.For scattered cementation,the distribution of the calcite cement is not controlled by the sand-shale contact.Calcite cement was preferentially distributed in coarse-grained sandstones,indicating that sandstones with high original permeability are the preferred pathway for the migration of early diagenetic fluids.

关 键 词：turbidite sandstone calcite cement distribution patterns Dongying Depression 

分 类 号：P618.13[天文地球—矿床学]