南海西南次海盆与东部次海盆地质与地球物理分析  

Geological and Geophysical Analysis of the Southwestern and Eastern Sub-Basins, South China Sea

作　　者：丁巍伟[1,2] 陈汉林[1,2] 杨树锋[1] 初凤友[2,3] 

机构地区：[1]浙江大学地球科学系,浙江杭州310027 [2]国家海洋局海底科学重点实验室 [3]国家海洋局第二海洋研究所

出　　处：《高校地质学报》2002年第3期268-279,共12页Geological Journal of China Universities

基　　金：国家重点基础研究发展规划(973计划)(G2000046704)

摘　　要：在对南海西南次海盆和东部次海盆的地质和地球物理特征分析和对比的基础上,提出了南海东部次海盆的地球物理场异常和地质构造均呈EW向分布,而西南次海盆则表现为NE向分布。并利用插值切割法对南海深海盆的磁力异常场进行了分析处理,提出了其显示的地球动力学过程的差异,并对南海西南次海盆和东部次海盆的演化史进行了探讨:东部次海盆是在晚渐新世一早中新世通过SN向的海底扩张形成的,而西南次海盆是在中始新世至早渐新世通过NE向的大陆边缘裂谷作用形成的。In this paper, we will compare and analyse the geologic and geophysic characters of the Eastern and Southwestern Sub-basins of the South China Sea (SCS) and discuss the SCS' s tectonic evolution history.The results of studies suggest that the magnetic anomalies and the gravity anomalies of Eastern Sub-basin are in EW direction but in NE direction in the Southwestern Sub-basin. In both Sub-basins the Bouguer gravity anomalies in the central part are bigger than in the margins. This indicates that below the central part exists high density matter, which could be closely related to the spreading of the basin and the invasion of high density matter from the mantle.A computational process called the Interpolation Cut Methods was used to analyse the magnetic anomalies of the two Sub-basins. Results of the analyse indicate that the magnetic anomalies of the Southwestern Sub-basin is mainly affected by the shallow magnetic sources above about 5km in NE-SW direction. Below 5km, the magnetic anomalies become blur, and the intensity decreases. The magnetic anomalies of the Eastern Sub-basin is not only affected by the shallow magnetic source above 5km, but also affected by the deep source. They are all in EW direction. The differences between the two Sub-basins reflect the different tectonic mechanisms.Most faults in SCS exist in the conjunctional area of the Circum-Pacific tectonic belt and theTethys tectonic belt and are effected by both belts. The faults in SCS basin is mostly in NE and near EW directions. The NE direction faults formed the structure frame work of the Southwestern Sub-basin and the western part of the Eastern Sub-basin. The formation of the NE direction faults are same in the mechanism and time as the faults in the Eastern China, which were commonly formed in Yanshanian stage. In the Himalayan stage, because the main tectonic point moved to east, the NE direction faults of the Southeast China formed earlier and was relatively stable; the EW direction faults formed later and then cut across the NE directi

关 键 词：南海 海盆 地球物理特征 磁力异常场 插值切割法 活动断裂 形成机制 

分 类 号：P544.4[天文地球—构造地质学]