辽河西部凹陷雷家地区古近系沙四段湖相白云岩成因  

Genesis of lacustrine dolomites of the fourth member of Paleogene Shahejie Formation in Leijia area,Western Liao Depression

作　　者：李甜 代宗仰[1] 李阳[1] 黄蕾 宫振超[3] 赵晓阳 周晓龙[3] 黄澜 LI Tian;DAI Zongyang;LI Yang;HUANG Lei;GONG Zhenchao;ZHAO Xiaoyang;ZHOU Xiaolong;HUANG Lan(School of Earth Science and Technology,Southwest Petroleum University,Chengdu 610500,China;Research Institute of Exploration and Development,Sinopec Zhongyuan Oilfield Company,Puyang 457000,Henan,China;Research Institute of Exploration and Development,PetroChina Liaohe Oilfield Company,Panjin 124010,Liaoning,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]中国石化中原油田分公司勘探开发研究院,河南濮阳457000 [3]中国石油辽河油田分公司勘探开发研究院,辽宁盘锦124010

出　　处：《岩性油气藏》2022年第2期75-85,共11页Lithologic Reservoirs

基　　金：中国石油天然气股份有限公司重大科技专项“辽河探区可持续规模增储勘探关键技术研究”(编号:2017E-1601)资助。

摘　　要：通过岩石学特征、主微量元素、碳氧同位素等地球化学特征分析,明确了辽河西部凹陷雷家地区古近系沙四段湖相白云岩的成因。研究结果表明:①研究区白云岩沉积时,湖盆水体较咸,且处于强还原环境,以泥晶级白云岩为主,有均匀分散型、纹层状富集型2种产状。②研究区白云岩的δ^(18)O值平均为-4.4‰,δ^(13)C值平均为8.7‰,整体上具有“碳同位素偏正、氧同位素偏负”的特征,反映沉积水体整体上咸化的特征;阴极发光测试结果为不发光或发昏暗光、发暗红色、橘黄色光;稀土元素具有轻稀土相对富集、弱Eu正异常的特征,稀土元素配分模式显示含方沸石白云岩与下伏房身泡组碱玄岩和同层位玄武岩具有一定的亲缘性。③研究区白云岩具有准同生白云岩化和热水沉积白云岩化2种成因类型:准同生白云岩化以泥晶结构为主,晶粒细小,有序度低,富钙贫镁,为高盐度湖水交代而成;深部热液流体携带大量阳离子喷涌出地表并与湖水混合,从而形成热水沉积岩。The petrological characteristics,major and trace elements,carbon and oxygen isotopes and other geochemical characteristics were used to analyz the genesis of lacustrine dolomites of the fourth member of Paleogene Shahejie Formation in Leijia area of Western Liaohe Depression.The results show that:(1)During the deposition of dolomites in the study area,the lake basin water bodies were relatively salty and in a strong reducing environment,dominated by micritic dolomites,with two types of occurrences:uniform dispersion and laminar enrichment.(2)The average values ofδ^(18)O andδ^(13)C of the dolomites in the study area are-4.4‰and 8.7‰respectively,the carbon isotope is positive and the oxygen isotope is negative,reflecting the characteristics of overall salinized water body.The cathodoluminescence test results are no luminescence or dim light,dark red and orange light.The rare earth elements are relatively enriched in light rare earth elements,and weak Eu positive anomaly.The distribution model of rare earth elements shows that the analcite-bearing dolomites have a certain affinity with the alkaline basalts of the underlying Fangshenpao Formation and the basalts in the same layer.(3)There are two genetic types of dolomites in the study area:quasi-syngenetic dolomitization and hydrothermal sedimentary dolomitization.The quasi syngenetic dolomitization is dominated by argillaceous structure,with fine grains,low order of dolomite and rich-calcium and poor-magnesium,which is metasomatized by high salinity lake water.Deep hydrothermal fluids carrying a large number of cations spewed out of the surface and mixed with lake water to form hydrothermal sedimentary rocks.

关 键 词：湖相白云岩 准同生白云岩化 热水沉积白云岩化 雷家地区 辽河西部凹陷 

分 类 号：TE348[石油与天然气工程—油气田开发工程] P581[天文地球—岩石学]