西太平洋洋-陆过渡带重磁异常与构造格架

Gravity-magnetic anomaly and tectonic units in West Pacific Continent-Ocean Connection Zone

西太平洋的重磁异常和构造格架一直是研究的热点,本文使用最新的覆盖全球的重力和磁力数据,在前人研究的基础上,重新对西太平洋洋-陆过渡带的重力异常进行了研究,使用离散小波变换、解析延拓和Parker-Oldenburg迭代反演法,反演得到了西太平洋莫霍面深度,结合水深地形数据,得到地壳厚度;通过对地壳厚度的分析,结合磁异常场分布,重新绘制了该区的超壳断裂体系分布图,明确了断层对西太平洋构造格架的控制作用,在此研究基础上,海陆综合考虑,结合地块构造层序列、沉积建造、变质作用以及构造演化历史,以地块之间的蛇绿岩带、洋-陆转换带、俯冲带和洋中脊作为二级构造单元的分界线,对东亚大陆构造域和东亚大陆边缘构造域划分出9个二级构造单元和40个三级构造单元,依据地壳类型、位置与板块边缘的性质以及动力学模式,划分了中国近海24个盆地的类型,明确了西太平洋-中国海的现今基本构造格局及演化特征。

The geomagnetic and gravitational fields and tectonic evolution in the West Pacific Continent-Ocean Connection Zone have always been a hot issue for geologists and geophysics experts.By using the latest global spherical gravity model and synthetizing the published results,the gravity anomaly of the West Pacific Continent-Ocean Connection Zone has been analyzed in the paper,with the method of discrete wavelet decomposition,analytic continuation,and Parker-Oldenburg iterative inversion.As a result,the Moho depth of the study area is inversed,and the crust thickness is obtained by combining the Moho depth with the bathymetric data of the area.By analyzing the crust thickness and the magnetic anomaly,the fault distribution of the study area is mapped,and the faults controlling the tectonic framework in the West Pacific ContinentOcean Connection Zone are identified.Based on the identified fault system,combining with the crust analysis on both the continent and the ocean,there are 9second-grade tectonic units and 40third-grade tectonic units have been classified out of the continental tectonic domain and continental margin tectonic domain in the East Asia-West Pacific area.The tectonic levels,sedimentary formations,metamorphism and tectonic evolutional history for each block have been summarized in the paper,and the second-grade tectonic units are well bounded by the suture zones,ophiolite belts,ophiolite mélange belts,subduction zone,continent-ocean transition zone or spreading centres.In addition,24 offshore basins have been classified based on their crust types,block positions,plate margin properties and the geodynamic models.And the basic tectonic units and evolution of the West Pacific-China Sea have been identified and documented.