关于西沙海槽正磁异常带的地球物理认识  

A geophysical understanding of a positive magnetic anomaly zone in the Xisha trough

作　　者：张永军[1,2] 刘振军[2] 赵百民[2] 

机构地区：[1]中国科学院地质与地球物理研究所油气资源研究重点实验室,北京100029 [2]中国国土资源航空物探遥感中心,北京100083

出　　处：《地球物理学进展》2009年第6期1987-1994,共8页Progress in Geophysics

基　　金：国家专项与国家973计划项目(2007CB411701)联合资助

摘　　要：南海北部西沙海槽存在东西向正磁异常带,长约350 km,前人推测为基性或超基性物质反磁化的反映.通过对西沙海槽大比例尺高精度航磁资料分带化极处理和反演拟合,发现西沙海槽正磁异常带由海槽北缘隐伏强磁性体斜磁化引起.磁性体埋深超过9 km,推测是残留洋壳(蛇绿岩),为海南岛昌江—琼海断裂带或海南岛九所—陵水断裂带所代表的缝合带在南海北部的延伸段.There is an EW positive magnetic anomaly zone in the Xisha trough of the northern South China Sea which is about 350km long. It is inferred that it results from basic or ultra-basic rock with reverse magnetic induction in the Xisha trough. Based on the large-scale and high resolution aeromagnetic data reduced to the pole and inversion, it is revealed that the positive magnetic anomaly zone in the Xisha trough is caused by high-magnetic blocks located in the northern margin of the Xisha trough. The high-magnetic blocks are 9 km under ground and possibly residual oceanic crusts （or ophiolites）. It is probably a part of the sutural zone that is marked by the Cangjiang-Qionghai fauh zone or Jiusuo-Lingshui fault zone in the Hainan Island.

关 键 词：西沙海槽 反磁化 航磁 残留洋壳 缝合带 

分 类 号：P738[天文地球—海洋地质] P318[天文地球—海洋科学]