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中国东部海区及其邻域受到来自欧亚、太平洋和菲律宾海板块运动的共同作用,其是认识中国边缘海形成演化的天然实验室.本文通过分析中国东部海区及其邻域的地球物理场特征,采用重力反演方法计算了该地区的莫霍面深度,根据地震层析成像的反演结果分析了研究区的地壳和岩石层速度结构,并从地热、断裂带、天然地震分布和应力场特征等方面对该区域的地球动力学特征做了进一步的分析.通过分析、反演计算可以得出:中国东部海区的陆架区的重、磁场特征与中国大陆重、磁场特征分布趋势与走向相同,是大陆地球物理场向海域的延伸.东海陆架盆地区和中国大陆东部的地壳结构和走向趋势相同,是大陆地壳向海域的延伸.东海东部及其边缘海域、海槽为过渡性质地壳,由于地壳性质的转变,说明冲绳海槽应为东海大陆架的自然终结.地震层析成像反演结果为研究岩石层地幔的结构组成以及形成演化的深部动力因素提供了依据,32+km深度处的速度图像基本上反映出莫霍界面正下方的速度分布特征及莫霍面的起伏形态,其与重力反演计算的结果相符合.70km深度上的速度图像反映出东部海区深部结构南北分块的特征,海区表现负速度扰动,推断已部分进入软流圈.110km深度处的速度图像表现为大范围的低速异常,只有扬子块体有正异常显示,进一步验证华南华北块体减薄.中国东部海区及其邻域地球动力学特征主要为:冲绳海槽高热流异常区显著,热流分布明显和沟弧盆体系的构造特征相吻合,呈现NE向条带状分布;断裂体系显示出“东西成带”的待征;冲绳海槽和琉球海沟区域具有地震活动的成带性,地震震中的分布密度远大于远离板块边界的大陆内部;其现代应力场从北到南由NE向逐渐转为NEE至SE向,总体呈向东发散的扇形分布.
The eastern China sea area and its adjacent areas are jointly affected by the movement of the sea plate from Eurasia, the Pacific Ocean and the Philippine Sea, which is a natural laboratory for understanding the formation and evolution of the marginal sea in China.Through analyzing the geophysical characteristics of the eastern China sea area and its adjacent areas , The Moho depth in this area was calculated by gravity inversion method. Based on the inversion results of seismic tomography, the crustal and lithospheric velocity structures in the study area were analyzed. From the geothermal, fault zone, natural earthquake distribution and stress field Characteristics and other aspects of the geodynamical characteristics of the region made a further analysis by analysis and inversion calculations can be drawn: the eastern China Sea Shelf area of heavy and magnetic properties and the Chinese mainland, the distribution of magnetic characteristics and trend of the same , Is an extension of the continental geophysical field to the sea.The crustal structure and trend of the East China Sea continental shelf basin and eastern China are the same and extend to the sea area from the continental crust to the sea area.The eastern part of the East China Sea and its marginal sea area and the trough are transitional crust, The change of the crustal nature shows that the Okinawa Trough should be the natural end of the East China Sea continental shelf. The results provide the basis for the study of the structural composition of mantle in the lithosphere and the deep dynamical factors of evolution. The velocity images at the depth of 32 + km basically reflect the velocity distribution characteristics and the waviness of the Moho, The results of gravity inversion are consistent with each other.The velocity images in the depth of 70 km reflect the characteristics of the north-south block of the deep sea structure in the eastern sea area, and the sea area exhibits the negative velocity perturbation, which is partly inferred to asthenosphere.The velocity image at depth of 110 km shows large Only the Yangtze block shows a positive anomaly, further verifying the North China block thinning in the South China.The geodynamic characteristics of the eastern China sea area and its adjacent areas are mainly as follows: the anomalous area of the Okinawa Trough is significant, the heat flow distribution is obvious and The structural features of the arc-arc basin system coincide with each other and show a NE-banded distribution. The fracture system shows that the “east-west belt” is to be levied. The Okinawa Trough and the Ryukyu Trench Zone have the characteristics of seismic activity, The distribution density is far greater than the interior of the continent away from the boundary of the plate; the modern stress field gradually changes from NE to NEE to SE from north to south, showing an eastward fan divergence .