柴达木盆地南翼山地区微生物碳酸盐岩结构与矿化作用  

The characteristics of Cenozoic microbial carbonates fabric and mineralization mechanisms in the Nanyishan area,Qaidam basin

作　　者：李国欣 王建功[3,4] 张永庶 李翔[3] 高妍芳[3] 孙秀建[3] 张世铭[3] 刘合[5] 鲜成钢[1] LI Guoxin;WANG Jiangong;ZHANG Yongshu;LI Xiang;GAO Yanfang;SUN Xiujian;ZHANG Shiming;LIU He;XIAN Chenggang(Key Laboratory of Petroleum Resources and Exploration(China University of Petroleum),Beijing102249,China;PetroChina Qinghai Oilfield Company,Dunhuang,Gansu 736202,China;Northwest Branch of Rsearch Institute of Petroleum Exploration and Development,CNPC,Lanzhou,Gansu 730020,China;Key Laboratory of Reservoir Description of CNPC,Lanzhou,Gansu 730020,China;Research Institute of Petroleum Exploration and Development,CNPC,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油青海油田公司,甘肃敦煌736202 [3]中国石油勘探开发研究院西北分院,甘肃兰州730020 [4]中国石油集团油藏描述重点实验室,甘肃兰州730020 [5]中国石油勘探开发研究院,北京100083

出　　处：《地质学报》2023年第1期133-149,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42172169);中国石油天然气集团公司前瞻性科研项目(编号2021DJ0305,2021DJ0201,2021DJ0803)联合资助的成果。

摘　　要：为明确柴达木盆地西部地区新生界微生物碳酸盐岩微观结构及主要造岩矿物的成因机理,本文利用岩芯观察、薄片分析、扫描电镜及电子探针分析等实验测试方法,对南翼山地区上油砂山组微生物碳酸盐岩微观结构、矿物特征差异性及矿化作用开展研究。分析认为南翼山地区上油砂山组发育厚层泥晶碳酸盐岩,单层厚度3~5 m;局部发育薄层微生物碳酸盐岩,单层厚度以30~50 cm为主,单层最大厚度2 m。微生物碳酸盐岩类型以凝块石为主、局部发育叠层石,二者混合共生,通过扫描电镜在微生物碳酸盐岩中发现了大量钙化的细胞外聚合物(EPS)组构与少量微生物化石,为湖相微生物碳酸盐岩的形成提供了生物学证据。研究结果表明:(1)微生物碳酸盐岩主要矿物类型为方解石,微观组构复杂、类型多样,包括球粒、团粒、菱面体以及片状结构等。球粒粒径分布范围50~80 nm。团粒由若干纳米级球粒聚合黏结形成,粒径为几微米至几十微米。片状方解石往往大小不等、形态各异,粒径通常为1~10μm。(2)发现大量钙化EPS组构及疑似微体化石,包括球状、杆状及丝状体。杆状体微生物化石直径约0.4μm,长0.5~1μm。丝状体微生物化石直径约0.3~0.5μm,长1~2μm。(3)方解石矿物的形成主要以有机矿化作用(或微生物诱导矿化作用)为主、生物矿化作用次之,其中,球粒方解石主要为有机矿化作用控制(或微生物诱导)形成。杆状和丝状体化石保持了微生物的形貌特征,分析认为可能由生物矿化作用控制形成。(4)凝块石中的球粒、卵球袋及团块的形成,可能由微生物膜及其所封闭的微生物菌落钙化形成,分析认为此类矿物可能与有机矿化作用具有相关性。In order to clarify the fabrics of Cenozoic microbial carbonate and the genetic mechanisms of main rock forming minerals in the Qaidam basin,the petrographic classification,fabric identification,difference analysis of mineral morphological characteristics and Org-mineralization and biomineralization of microbial carbonates were studied by using a large number of core observation,thin section analysis,scanning electron microscope and electron probe analysis,and other analysis methods,focusing on the microbial carbonates of Youshashan Formation in Nanyishan-Dafengshan area.The analysis shows that the Youshashan Formation in Nanyishan area is developed with the thick layer of argillaceous carbonate rocks,with the thickness of 3~5 m;and the thin layer of microbial carbonates,with the thickness of 30~50 cm,the maximum thickness of microbial carbonates is about 2 m.It is considered that the microbial carbonates of Youshashan Formation in this area are mainly thrombolites and locally developed stromatolites.They are mixed and symbiotic.A large number of microbial fossils are found in the microbial carbonates by scanning electron microscope,which provides biological evidence for the formation of lacustrine microbial carbonates.The results showed that:(1)The main mineral type of microbial carbonates is calcite,with complex micro morphology and various types,including spherical,agglomerates,rhombohedron and flaky structures.The distribution range of spherical particle size is 50~80 nm.The agglomerates are formed by polymerization and adhesion of several nano-sized spherical particles,and the particle size is several microns to tens of microns.Flaky calcite often varies in size and shape,with particle sizes typically ranging from 1 to 10μm.(2)A large number of calcified EPS fabrics and suspected microfossils were found,including spherical,short rod and filamentous fossils.The sizes of rod-shaped microbial fossils is about 0.4μm in diameter and 0.5~1μm long.Filamentous microbial fossil is about 0.3~0.5μm in diameter and

关 键 词：湖相碳酸盐岩 微生物岩 生物矿化作用 有机矿化作用 生物膜 微生物席 柴达木盆地 

分 类 号：P618.13[天文地球—矿床学]