摘要
利用大量露头和岩心薄片及分析化验资料,对柴达木盆地西部地区新生界咸化湖相微生物碳酸盐岩的岩石学特征、微观结构、岩相组合、沉积环境及其控制因素进行了研究。研究结果表明:(1)柴西地区微生物碳酸盐岩岩相组合受古地貌、沉积环境、陆源碎屑供给等因素影响,可分为扇控型和湖控型,扇控型主要发育在湖泊边缘的滨岸环境,分布范围大;湖控型多发育在盆缘斜坡区、断阶带及盆内浅水区,分布范围较小;古近系下干柴沟组上段主要发育扇控型,湖控型发育较局限,上述2类岩相组合在新近系下油砂山组均发育。(2)研究区不同岩相组合中微生物碳酸盐岩的类型与结构特征存在较大差异,扇控型微生物碳酸盐岩形成于湖侵时期,正旋回沉积为主,主要是凝块石,常叠置于厚层块状砂砾岩之上;微观结构以团块(凝块)、球粒及聚合粒为主;矿物成分以亮晶方解石为主。湖控型微生物碳酸盐岩在湖侵、湖退时期均可发育,正、反旋回沉积均发育,凝块石、叠层石及二者共生层均发育,规模相对较小,多与泥晶碳酸盐岩互层;微观结构更复杂,团块(凝块)、球粒及聚合粒和叠层结构均发育;矿物成分以方解石和白云石为主,含丰富的陆源碎屑、黏土矿物等,混积特征明显。(3)研究区扇控型微生物碳酸盐岩的形成主要受控于有机矿化作用和化学沉淀作用;湖控型微生物碳酸盐岩的形成则受控于有机矿化作用、化学沉淀作用以及物理沉积作用。
Based on a large number of outcrops and core thin sections and analytical data,the petrological characteristics,microstructure,lithofacies assemblage,sedimentary environment and its controlling factors of Cenozoic saline lacustrine microbial carbonate rocks in western Qaidam Basin were studied.The results show that:(1)The lithofacies assemblage of microbial carbonate rocks in western Qaidam Basin can be divided into fan-controlled type and lake-controlled type due to the comprehensive influence of paleogeomorphology,sedimentary environment and terrigenous clastic supply.The fan-controlled lithofacies assemblage is mainly developed in the coastal environment at the edge of the lake,with large thickness and wide distribution,while the lake-controlled lithofacies assemblage is mainly developed in the basin margin slope area,fault terrace zone and shallow lakes in the basin,with small thickness and small distribution.The upper member of Paleogene Xiaganchaigou Formation is dominated by fan-controlled lithofacies assemblage,with relatively limited lake-controlled lithofacies assem-blage.Two types of lithofacies assemblages are developed in Neogene Xiayoushashan Formation.(2)The types and structural characteristics of microbial carbonate rocks in different lithofacies assemblages in the study area are quite different.Fan-controlled microbial carbonate rocks were formed in the lake transgression period.They were mainly deposited in a positive cycle,mainly consisting of thrombolites,and often stacked on thick massive glutenite.The microstructure is mainly composed of agglomerates(clots),spherules and aggregates,and the mineral composition is mainly sparry calcite.Lake-controlled microbial carbonate rocks can be developed during lake transgression and lake regression.Both positive and reverse cycle sediments are developed,and thrombolites,stromatolites and their symbiotic layers are developed,with relatively small scale,and most of them are inter-bedded with argillaceous carbonate rocks.The microstructure is more complex,
作者
王建功
李江涛
李翔
高妍芳
张平
孙秀建
白亚东
左洺滔
WANG Jiangong;LI Jiangtao;LI Xiang;GAO Yanfang;ZHANG Ping;SUN Xiujian;BAI Yadong;ZUO Mingtao(PetroChina Research Institute of Petroleum Exploration and Development-Northwest,Lanzhou 730020,China;Key Laboratory of Reservoir Description,CNPC,Lanzhou 730020,China;PetroChina Qinghai Oilfield Company,Dunhuang 736200,Gansu,China)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2023年第3期1-17,共17页
Lithologic Reservoirs
基金
国家自然科学基金“柴达木盆地西部中新世混积岩对气候环境的双重重建”(编号:42172169)资助。
关键词
扇控型
湖控型
混积
微生物碳酸盐岩
矿化作用
岩相组合
咸化湖泊
新生界
柴西地区
fan-controlled type
lake-controlled type
mixed sedimentation
microbial carbonates
mineralization
lithofacies assemblage
saline lake
Cenozoic
western Qaidam Basin
