四川盆地高石梯-磨溪地区灯影组热液白云石化作用  

Hydrothermal dolomitization in Sinian Dengying Formation, Gaoshiti-Moxi area, Sichuan Basin, SW China

作　　者：蒋裕强[1,2] 陶艳忠[1,2] 谷一凡 王珏博[1,2] 强子同[1,2] 江娜[1,2] 林刚[1,2] 蒋婵[3] 

机构地区：[1]四川省天然气地质重点实验室 [2]西南石油大学地球科学与技术学院 [3]中国石油西南油气田公司勘探事业部

出　　处：《石油勘探与开发》2016年第1期51-60,共10页Petroleum Exploration and Development

摘　　要：基于四川盆地高石梯—磨溪地区基本地质条件、白云岩矿物组合及地球化学特征,研究该区震旦系灯影组热液白云石化作用形成条件、存在证据、具体改造方式及作用时期。高石梯—磨溪地区是四川盆地灯影组气藏的重要勘探目标,区域地质上具备发生构造控制热液白云石化作用的基本条件:1拉张性基底断裂活动;2深埋藏热液储库;3上覆地层的覆盖和封堵。通过对区内灯影组岩心样品开展岩相学研究和地球化学(微量元素,碳、氧、锶同位素,包裹体均一化温度等)测试分析,据密西西比谷型(MVT)矿物组合和地球化学特征,认为区内灯影组白云岩地层内存在构造控制热液白云石化作用。区内热液白云石化作用主要是指热液流体对基质白云岩的改造,包括3种具体改造方式:1溶蚀与充填作用;2重结晶和新生变形作用;3水力压裂作用。热液白云石化作用推测存在多期,即晚震旦世—早寒武世、晚泥盆世和晚二叠世。The formation conditions, existence evidence, modification modes and timing of hydrothermal dolomitization in the Sinian Dengying Formation are studied based on the basic geological conditions, mineral assemblages in dolomites, and geochemical features of the Gaoshiti-Moxi area in the Sichuan Basin. The Gaoshiti-Moxi area is a significant exploration target of the Sinian Dengying Formation in the Sichuan Basin and has the basic conditions of regional geology for the occurrence of structurally controlled hydrothermal dolomitization： （1） activity of extensional basement-fault; （2） deep-burial hydrothermal reservoirs; （3） the overlying seal strata. Based on the petrographic analysis and geochemical tests （trace elements （Fe and Mn）, stable isotopes （C, O, and Sr）, homogenization temperature of fluid inclusions, etc.） of the core samples of the Dengying Formation in the study area, combing with the MVT mineral assemblages and geochemical characteristics, the study demonstrates that structurally controlled hydrothermal dolomitization exists in the Dengying Formation of the study area. This type of hydrothermal dolomitization refers to transformation of matrix dolomites by hydrothermal fluids and it consists of three modes： （1） dissolution and cementation; （2） recrystallization and neomorphism; （3） hydrofracturing. It is inferred that there exists multi period of hydrothermal dolomitization, namely, Late Sinian to Early Cambrian, Late Devonian and Late Permian.

关 键 词：热液白云石化作用 密西西比谷型矿物组合 地球化学特征 震旦系 灯影组 高石梯-磨溪地区 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]