CHARACTERISTICS OF MAGNETIC LINEATIONS AND TECTONIC EVOLUTION OF THE SOUTH CHINA SEA BASIN

Based on the analysis of new data of a total of 60 000 km, the authors propose a new spreading model of the tectonic evolution of the South China Sea Basin and suggest that magnetic anomalies in the Basin are the magnetic anomalies of a new type in marginal basins, that the tectonic development of the Basin can be divided into three seafloor spreading phases and that the southward migration of spreading ridge is related to the asymmetric spreading.     

南海中央海盆条带磁异常特征及构造演化

根据对60000千米新资料的分析,作者提出了南海中央海盆扩张的新模式,认为南海中央海盐磁异常是一种新的边缘海条带磁异常类型;对南海海盆的构造发展史划分了三个扩张期,并指出扩张脊的南移同不对称扩张有关.     

东海重磁场特征及构造格架

本文依据东海重磁调查资料,结合深部背景(莫霍面及地幔流应力场特征)的研究,对东海重磁场特征、构造格架和构造分区等问题进行了初步的讨论。图9,参考文献6。     

东海及琉球岛弧地区岩石圈层下地幔流应力场

本文使用C.A.Wagner等1977年公布的地球重力场球谐函数系数和S.K.Runcorn建立的球谐函数系数与地幔对流之间的关系式,分低阶场(2—12阶)、高阶场(13—25阶)、完全场(2—30阶)、甚高阶场(26—30阶)四种模式,计算了地幔对流对岩石圈层产生的牵引力。计算结果与有关地质、地球物理资料对比,较为符合。说明地幔流应力可能对构造发育起控制作用。图4,参考文献8。     

浙江沿海岛屿地质概查剪影

为进一步研究东海地质构造特征及海陆间的连接关系,海洋局二所地球物理室继东海西部周边地质调查之后,又于1982年10—12月间,对浙江沿海具有代表性的20余个岛屿进行了登岛调查。踏勘路线北起嵊泗列岛南至台州列岛。历时47天。调查项目主要为地质观测及标本采集、岩石物性参数测定、地貌及新构造运动观察、砾石球度统计和应力场特征研究等。 这次岛屿概查,取得了大量的实地观测资料,为东海地质构造特征及其发育史的深入研究,提供了一定的科学依据。     

ORIGIN AND EVOLUTION OF THE EAST CHINA SEA BASIN

Based on the infotmadon and samples of sediments obtained from the geophysical and bathy-metric surveys over an area about 450,000 km2 (scale 1/1,000,000) in the East China Sea by the Natonal Bureau of Oceanography this peper describes the influence on the margin of the East Asia Continent exerted by the interaction of the Eurasian Pacific and Indo Plates since the Indo-China Movement, especially by the formation of the Philippine Sea Plate, which were the factors controlling the development of the sea domain. The origin and evolution of the East China Sea Basin, and the geotectonic characteristics and subdivision of the East China Sea are discussed.