万安盆地重力场与断裂特征研究  

Research on Gravity Field and Fracture Characteristics of Wan′an Basin

作　　者：寻博靖 Xun Bojing(School of Earth Sciences and Engineering,Xi＇an Shiyou University,Xi＇an Shaanxi 710065)

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065

出　　处：《中外能源》2017年第1期35-40,共6页Sino-Global Energy

基　　金：西安石油大学研究生创新基金(项目编号:2015cx140220)资助

摘　　要：基于万安盆地地区的布格重力异常分布特征,在前人研究的基础上,通过滑动平均滤波法,将重力异常划分为区域场和局部场;利用水平总梯度法,强化深断裂的线性特征。结合区域地质、地震等相关资料,推断了盆地内断裂构造:一级断裂4条,二级断裂5条,三级断裂26条。将本次研究的断裂分布与前人研究进行对比得到新认识:位于万安盆地中部的F1-1断裂是形成于中生代的一条基底断裂,可能是南海西缘断裂带在万安盆地内的延伸段;万安盆地东缘断裂带不是一条断层,而是呈雁行排列的断层组,主断裂是一个左旋、右旋相互交替、多期活动的走滑断裂,对盆地形成东断西超断陷特征有强烈的控制作用。万安盆地处于南海地质构造最复杂的南部地区,经历了多次构造运动和多阶段演化,其构造演化受南海海底扩张和万安走滑断裂带的双重控制,断裂系统极其发育。Based on distribution characteristics of Bouguer gravity anomaly in Wan′an basin and previous researches,the gravity anomaly was divided into regional field and local field using moving average filtering method.The method of total horizontal gradient was applied to enhancing the linear features of deep fractures.Combined with related regional geology and seismic data,the fault structure in the basin was inferred： there were 4 first-order fractures,5 second-order fractures and 26 third-order fractures.Some new understanding was known through the comparison of the researched fracture distribution with the previous results.F1-1 fracture located in the middle of Wan′ an basin is a basement one originated in the Mesozoic,which may be the extension of the western-edge fault zone of the South China Sea in Wan′an basin.East-edge fault zone in Wan′an Basin is not a fault but an en echelon fault group.Its major fault is a strike-slip one with laevogyrate and dextral alternating and multi-period activity,which has strong control on the formation of the east-faulting and west-overlapping char-acteristics of the basin.Wan′an basin locates in the south region with the most complex structure of the South China Sea,where many tectonic movements and multi-stage evolution took place.Its tectonic evolution was con-trolled by the seafloor spreading of the South China Sea and Wan′ an strike-slip fault zones,and the fracture system was extremely developed.

关 键 词：万安盆地 重力异常 断裂构造 基底断裂 

分 类 号：P618.13[天文地球—矿床学] P631.1[天文地球—地质学]