【摘要】 苏鲁-大别造山带是华北、华南地块之间的大地构造交界带。本文分析研究了我国东部地区的3000余年的地震活动性,并根据1918～2006年间苏鲁-大别及其周围地区发生的1000余个地震的震源机制解,系统研究了地壳应力场和构造运动的区域特征,探讨了超高压变质带的折返机制。结果表明,苏鲁带以及华北地区受到太平洋板块向欧亚板块俯冲挤压的同时,受到从贝加尔湖经过大华北直到琉球海沟的广阔地域里存在着的统一的、方位为170°的引张应力场的控制。右旋走滑运动是苏鲁地区和郯庐断裂带的现代构造运动的主要特征。地震发生类型多为右旋走滑型或右旋走滑正断层型地震。华南地区构造应力场主要表现为,受北西西向运动的菲律宾板块向欧亚板块碰撞挤压运动所产生的方位为110～120°挤压应力的控制。华北、华南地块之间现代地壳应力场的分界线,西部与秦岭带大致相符,在大别东开始则逐渐偏离大地构造,到黄山附近向东南偏转,在温州附近转为向东延伸,最终穿过东海直至琉球海沟。研究结果还表明,苏鲁-大别超高压变质带的折返运动机制,即致使大量超高压变质岩折返到上地壳或地表的岩石圈应力场背景原因为,中生代以来大华北地区存在着较强扩张应力场的主控作用。此外,岩石圈地幔的蘑菇云构造增强了华北地区扩张应力场及扩张构造运动,导致形成大量深裂谷、裂隙,深部物质上涌。苏鲁及东大别地带处于或接近蘑菇云构造运动发育地区的中心,深部地幔物质的上涌导致并加剧了超高压变质岩折返到上地壳或地表,形成了世界著名的苏鲁-大别超高压变质带。更多还原

【Abstract】 The Sulu-Dabie orogen belt is a tectonic boundary between the North and the South China.In present paper,the regional characteristics of seismic activity,the modern crustal stress field,tectonic motions and its dynamics have been analyzed in east China in detail based on the focal mechanism solutions of more than 1000 middle and great earthquakes occurred during 1918 and 2006.The results suggest that the crustal stress field and tectonic movement in the North China and the South China are attributable to relative motions among the Pacific Ocean,the Philippine Sea and the Eurasian plates,and interactions along blocks of mainland.The North China are controlled by the compressive stress in a NEE direction due to subduction of the Pacific Ocean plate and the identical tensile stress in 170 in a broad region from the Baikal to the Ryukyu trench throughout the North China.The mechanism solutions of large events occurred in the North China showed that they were attributed to the action of the compressive in the NEE direction and the tensile in the NNW direction.The earthquakes occurred in the North China were caused by the right strike-slip faults,which also shows the characteristics of tectonic movement here.The compressive force in a NWW direction from the Longitudinal valley in Taiwan controls the crustal stress field in the South China up to the eastern region of southern part of the North-South Seismic Belt(NSB).The results obtained in this study show that there is a boundary of regional crustal stress field between the North China and the South China.This boundary mainly consistent with the Qinling belt in its western part,however,it deviates in and east of the Dabie belt and turns to the south-east at 30°N,passes the Wenzhou area at 27°N,throughout the East Sea of China,finally up to the Ryukyu trench.The results also suggest that the exhumation mechanism of the ultrahigh-pressure metamorphic belt in and around the Sulu-Dabie orogenic belt may be caused by the strong tensile stress since Mesozoic and the mushroom structure of the lithosphere in the North China.更多还原