南海深海盆磁异常分析及其动力学意义  

Apply the interpolation cut method in magnetic anomaly analyse of the South China Sea.

作　　者：丁巍伟[1] 陈汉林[1] 杨树锋[1] 初凤友[2] 邹乐君[1] 沈晓华[1] 

机构地区：[1]浙江大学地球科学系 [2]国家海洋局第二海洋研究所

出　　处：《浙江大学学报（理学版）》2003年第2期223-229,共7页Journal of Zhejiang University（Science Edition）

基　　金：国家重点基础研究发展规划项目 (G2 0 0 0 0 4670 4)

摘　　要：在南海深海盆分布着大范围规律性很强的条带状磁异常 .通过插值切割法对其中东部次海盆和西南次海盆的磁异常进行分析 .发现南海深海盆区的磁力异常具有叠加性 ,西南次海盆主要受约 5 km以上的浅部磁源的影响 ,表现为 NE- SW向展布 ,5 km以下磁异常的展布开始变得模糊 ,强度也变弱 ;而东部次海盆不仅受 5 km以上的EW向浅部磁源的影响 ,同时深部磁源也起着很大的作用 ,在方向上也表现为 EW向 ,但是强度随着深度而减弱 .由此提出了两海盆地磁异常差异所反映的地球动力学过程 ,认为西南次海盆的磁源是通过大陆边缘裂谷作用过程形成 ;而东部次海盆深部和浅部磁异常的磁源具有同时性和相同形成机理 ,是通过海底扩张作用的方式形成的 .在结合其他研究结果的基础上 。In the central sea basin of the South China Sea(SCS), there are vast prominently regular stripled magnetic anomalies. Using the interpolation cut method, the anomalies of the Eastern Sub basin and the Southwestern Sub basin are analysed. Using different cut radii, the regional magnetic anomalies and the partial ones are gotten. It shows that the magnetic anomalies of the SCS are folded. The Southwestern Sub basin is mostly affected by the shallow magnetic source above 5 km, which distributes in NE SW direction. Below 5 km the distribution become blur, and the intension also decreases. The Eastern Sub basin is not only affected by the shallow source which distributes in EW direction, but also affected by the deep one distributed in EW direction too. The magnetic intension decreases with increasing depth. It is suggested that the Southern Basin's magnetic source is controlled by the crustal breaking up and south eastward rifting. In the Eastern Sub basin the shallow and the deep magnetic sources have the same time and mechanism in formation, and are controlled by the seafloor spreading. Combining other researches in this area, the SCS's tectonic mechanism and evolution history were discussed.

关 键 词：南海 磁异常 东部次海盆 西南次海盆 插值切割法 局域场 区域场 地球动力学机制 

分 类 号：P318.43[天文地球—固体地球物理学] P541[天文地球—地球物理学]