【摘要】 用分布于欧亚大陆及西太平洋地区106个宽频带数字地震台站约20000多个长周期波形记录,挑选出沿10600条大圆路径传播的瑞利面波,采用频散分析及波形拟合反演方法,对东亚及西太平洋边缘海地区地壳上地幔进行高分辨率三维层析成像。高分辨率速度成像表明,从上地壳到70km深,在东亚东部及西太平洋边缘海地区均为高速分布,西部以青藏高原为中心呈极低速分布。从100km至250km深,在东亚东部及西太平洋边缘海,自北向南显示出一条宽约2500km~4000km,长约8000km的巨型低速异常带。深度为300km~400km的平面图上,速度差异幅度不大,塔里木至扬子地块仍然显示为高速分布。东、西两部份岩石圈与软流圈的结构有着巨大的差异。西部主要是印度板块与欧亚板块碰撞引起的岩石圈汇聚增厚区;东部则主要是由于软流圈上涌(地幔热物质上升)引起的岩石圈拉张减薄区。古新世印度板块与欧亚板块的碰撞,岩石圈板片以低角度下插到青藏高原之下,引起高原隆起和地壳增厚,西部地区成为岩石圈汇聚区。中生代中晚期东亚大陆东缘岩石圈解体,软流圈物质上涌,岩石圈减薄张裂,形成巨型低速带,并演化为东亚裂谷系。现今的西太平洋边缘海、沟弧盆体系,是新生代中晚期太平洋板块、澳大利亚板块与欧亚板块相互作用形成的。更多还原

【Abstract】 This paper deals with the high resolution Rayleigh surface wave tomography in east Asia and west Pacific marginal sea recorded by 106 digital seismic stations from CDSN, GSN, GDSN and GEOSCOPE network. 10600 accurate surface dispersion curves are employed for inversion. The high resolution 3-D shear wave velocity images in this area constructed by inversion of both dispersion and waveform show a notable lateral variation in the crust and upper mantle. The high resolution images of S wave velocity indicate that from upper crust to the depth of 70 km, the high velocity is displayed in the region of eastern part of East Asia and West Pacific marginal sea, in contrast, extreme low velocity illustrated in the Qinghai-Tibet plateau and its surrounding areas. From depth of 100 km to 250 km, a giant low velocities belt within the width about 250 km to 400 km and length about 8000 km are showed in the eastern part of East Asia and West Pacific marginal sea.The high velocity anomaly belts appeared along Izu-Bonin- Mariana trench. There exist significant differences in eastern and western parts for the lithospheric and asthenospheric structure with the boundary of longitude 110°E. The western part is the thickening convergent lithosphere, whereas the eastern part the thinning extension one arising from intrusion of asthenospheric material. The Thickness of lithosphere in western part is about 100 km thicker than eastern part in average. The evolution and geodynamic process is so different between the eastern part of East Asia and western part. In Paleocene epoch the Indian subcontinent collided with the Eurasian continent, and the Indian lithospheric sheet beneath the Qinghai-Tibet plateau with low angle subduction causing it uplift and forming the thickening lithospheric root. The eastern part was disassembly since late Mesozoic arising from intrusion of asthenospheric material causing lithosphere extension and thinning, then a giant rifting system formed. The current marginal sea and trench-arc-basin system of west Pacific is reformed by interaction of Pacific plate, Australian plate, and Eurasia Plate in Cenozoic.更多还原