东海重力磁力异常与地质构造

本文通过对重力、磁力异常的分析,结合陆、岛地质、地震、钻井资料进行综合解释,认为:大范围的平均布格重力异常,反映东海由西往东,莫霍面缓慢抬升,地壳变薄;大陆架莫霍面深度平均为30km。重力异常高低、磁力异常强弱及它们的走向变化,反映东海基底形成时代,由北向南、由西向东逐次变新,即前寒武纪→前中生代→前中新世。局部重力异常、磁力异常形态及分布规律,反映了断裂、岩浆活动及区域构造格架。东海的断裂、岩浆活动时期,由西北向东南,有由老变新的趋势;区域构造格架为三个隆起和两个盆地,由西向东为浙闽隆起区、东海陆架盆地、钓鱼岛隆褶带、冲绳海槽盆地、琉球隆褶区。

GRAVITY AND MAGNETIC ANOMALY AND THE GEOLOGICAL TECTONICS OF THE EAST CHINA SEA

Gravity and magnetic survey on the scale of 1:100000 is made in the East China Sea and a lot of geological informations were obtained by the first Brigade of Marine Geological survey.Based on the analysis of gravity and magnetic anomaly and the comprehensive interpretation of geological,seismic and drilling data of both continent and Islands,the authors consider that the average Bouguer anomaly in a broad range revealsthe slow uplifting of the Moho and the thinning of the crust from west to east in the East China Sea.The average Moho depth of continental shelf is 30km.The changes of gravity and magnetic anomaly and their strike show that the formationstages of the basement in the studied area progres sively turn younger from northto south and from west to east,i.e.,from the Precambrian to the Pre-Mesozoicand then to the Pre-Miocene.The shapes and distribution regularities of localgravity and magnetic anomaly indicate that the fault stages and volcanic activitiesfrom northwest to southeast have a new tendency of changing from old toyoung,and the regional tectonic framwork contains 3 uplifts and 2 basins,fromwest to east including Zhejiang-Fujian uplift zone the East China Sea shelfbasin,Diaoyu Island upwarping folded zone,Okinawa Trough basin and RyuKyu Archipelago upwarping folded zone.