川东南地区灯影组葡萄石地球化学特征及成因分析  

Geochemical characteristics and genesis of grapestone in Sinian Dengying Formation in south-eastern Sichuan basin

作　　者：施泽进[1,2] 梁平[2] 王勇[3] 胡修权[2] 田亚铭[4] 王长城[2] 

机构地区：[1]油气藏地质及开发工程国家重点实验室,成都理工大学,成都610059 [2]成都理工大学能源学院,成都610059 [3]成都理工大学核技术与自动化工程学院地球化学系,成都610059 [4]成都理工大学地球科学学院,成都610059

出　　处：《岩石学报》2011年第8期2263-2271,共9页Acta Petrologica Sinica

基　　金：国家自然科学基金委员会与中国石油化工股份有限公司联合基金项目(40739903);四川省重点学科“构造地质学”建设基金项目(SZD0408)联合资助

摘　　要：长期以来,人们对灯影组葡萄石的成因存在较大的争议。本文对灯影组葡萄石及基岩的地球化学特征进行了详细的对比分析,讨论了灯影组葡萄石的形成环境。灯影组葡萄石与基岩相比,具有较明显的Ce负异常和相对低的稀土总含量,说明了葡萄石并非是和基岩同时沉积而成;葡萄石中Na、K元素含量低而Mn、Fe含量较高,具有很低的Sr/Ba比值,同时具有碳、氧同位素明显偏负和87Sr/86Sr值偏高的特点,表明葡萄石是在淡水的作用下形成的。证实了灯影组在沉积过程中有过一次短暂暴露过程,这次沉积间断使灯影组暴露地表接受淡水淋滤,形成了小规模的岩溶现象,为葡萄石的形成创造了条件。这次短暂暴露过程对人们更好地理解葡萄石的成因及灯影组中部储层的形成有重要的意义。For a long time,there is a dispute about the genesis of the grapestone in Dengying Formation.The geochemical characteristics of grapestone and basement rock are analyzed and compared in detail and the genetic environments of the grapestone are discussed in this article.Compared with basement rock,there are relatively obvious Ce negative anomaly and relatively low total content of rare-earth elements in the grapestone,which indicates that the grapestone and basement rock were not deposited simultaneously.There are low content of Na,K,high content of Mn,Fe,low content of Sr/Ba ratio,high content of 87Sr/87Sr ratio and both carbon and oxygen isotope negative anomaly,which illustrates that the grapestone was formed under fresh water.It can be corroborated that there was a brief exposure during the deposition of Dengying Formation which made Dengying Formation expose to earth＇s face,leached by meteoric water and emerge small-scale karst to create the conditions for the genesis of the grapestone.The brief exposure has very important significance for a better understanding of the genesis of the grapestone and the development of the reservoirs in the middle of Denying Formation.

关 键 词：灯影组 葡萄石 稀土元素 微量元素 碳、氧、锶同位素 成因分析 

分 类 号：P588.245[天文地球—岩石学] P597.1[天文地球—地质学]