重磁异常揭示的浙江构造体系及岩石圈脱耦

Structural System and Decoupling Between Deep and Shallow in Lithosphere of Zhejiang Province—from Gravity and Magentic Field Characteristics

浙江省地处古新板块先后相互作用的关键地区却缺乏对地球物理资料进行细致的构造体系研究,本文基于最新的重磁异常资料,对浙江地区进行了系统的构造解析。磁力异常揭示出浙江具有典型的北东分带、北西分块的棋盘网格状特征,反映地面地质的构造走向;重力异常展现出包容早期北东向的主体由西南向东北逐渐升高的北西向构造并在深部与北北东向构造复合,进而揭示浙江现今深部构造与浅部地壳脱耦,深部莫霍面及岩石密度变化的重力梯度带与航磁异常并不同源。联系浙江及华南的地质现象,浙江为重磁异常构造为兼备北西向调节构造并被发育于燕山-喜山期的北北东向构造所改造的主体北东向构造;产生定型于基底的东西向构造在后期构造中活化并延续至今。

While Zhejiang Province is a key region where is locat in the ancient and the new plates takemutual activities, lack of detailed study on structural system by geophysical data.This paper systemanalysis the structure of Zhejiang province according to gravity and magentic field characteristics.Magnetic field characteristics of the region conform to the main geological structure on the ground with acheckerboard grid features along NE belts and NW blocks; Gravity anormalies increased from southwestto northeast show the main NW- tredning structure which enwrape the NE- trending structure wassuperposed by NNE- trending structure in the deep.Then reveal the decoupling between deep andshallow in lithosphere of Zhejiang province what can be explained by that the source lead to gravitygradient zone and magnetic anomaly zone are nonhomologous. Relate to geological facts of Zhejiangprovince and southern China, gravity and magentic field characteristics disclosure that the NE-trendingstructure combined with NW- trending adjustive structure were developed simultaneously andinterferenced by NNE-trending structure which generated in late-Yanshan and Himalayan; The EWtrendingstructure which were generated and positioned in the basement were reactivated by latertectonism and sustained activity until now.