南海东北部高磁异常带成因的地球物理反演研究  

Origin of high magnetic anomaly belt in northeastern South China Sea as indicated by geophysical inversion

作　　者：胡登科[1,2] 周蒂[1] 吴湘杰[3] 何敏[3] 

机构地区：[1]中国科学院边缘海地质重点实验室,中国科学院南海海洋研究所,广东广州510301 [2]中国科学院研究生院,北京100039 [3]中国海洋石油有限公司深圳分公司,广东深圳510240

出　　处：《热带海洋学报》2008年第1期32-37,共6页Journal of Tropical Oceanography

基　　金：国家自然科学基金项目(40576027)

摘　　要：南海东北部的高磁异常带是南海北部磁场最显著的特征,目前对其成因尚有不同推测。选取一条穿越该异常带的剖面,在多道地震解释及相关地质资料的约束下进行地球物理反演研究,验证其晚中生代俯冲增生带模式的可行性。结果表明,在东沙隆起带的前新生代基底中2.5—6km的深度上、宽约150km、密度2.65 g.cm-3、剩余磁化强度700×10-3A.m-1的中生代中酸性火山岩带可产生南海东北部的高磁异常带,与浙闽东部高磁异常带的成因相同,与晚中生代古太平洋向东亚陆缘的俯冲有关。The high magnetic anomaly belt is the most prominent feature in the northeastern South China Sea. Several explanations on its origin have been proposed. This paper selected a profile across the high magnetic anomaly belt for a gravity-magnetic inversion constrained by multichannel seismic data. The result indicates that the high magnetic anomaly may be generated by a about 150 km wide magnetic body at depth of 2.5--6km in the pre-Cenozoic basement. This body has residual magnetization of 700 × 10^-3A· m^-1 and density of 2.65 g·cm^-3 , and may be interpreted as intermediate to acid volcanic rocks similar to the volcanic rocks in the eastern Zhejiang and Fujian provinces. This validates the model that the high magnetic anomaly belt in the northeastern South China Sea was generated by a buried volcanic arc associated with the Late Mesozoic subduction of the paleo-Pacific plate under the SE Eurasian margin.

关 键 词：南海东北部 高磁异常 地球物理反演 俯冲增生带 中生代 

分 类 号：P738.3[天文地球—海洋地质]