中国中东部的双高压变质带  

THE PAIRED HIGH-PRESSURE METAMORPHIC BELTS IN EASTERN-CENTRAL CHINA

作　　者：刘晓春[1] 

机构地区：[1]长春地质学院

出　　处：《地质论评》1991年第4期300-309,共10页Geological Review

摘　　要：在我国中东部,华北板块和扬子板块之间,存在着两条紧密共生而变质作用类型不同的高压变质带。一条是以蓝片岩为代表的低温高压变质带、分布于东南一侧,主要由中一晚元古代双模式火山沉积变质岩系组成;另一条是以榴辉岩为代表的高温高压变质带,分布于西北一侧,主要由晚太古-早元古代结晶基底构成。两条高压带的变质年代基本一致,彼此以深断裂相接触。二者之间存在较明显的变质间断.其形成条件分别为0.7—1.4GPa,350—560℃和≥2.8GPa,680—840℃。双高压变质带的形成与晚元古代华北-扬子板块之间发生的陆内俯冲作用有关,俯冲的方向由扬子板块向华北板块进行。高温高压带俯冲的深度超过90km,并在连续俯冲-仰冲作用过程中快速向上抬升;低温高压带的俯冲深度约为25—50km,在俯冲速度降低或停止后,由于均衡作用使其逐渐抬升至地表。双高压变质带的确立对解决华北-扬子板块边界地球动力学演化问题具有重要意义。There exist two closely associated high-pressure metamorphic belts with different metamorphic types between the North China plate and Yangtze plate in eastern-central China. One is a low-temperature and high-pressure metamorphic belt represented by bluesehist, which is distributed on the southeastern side and composed mainly of middle-late Proterozoic bimodal metamorphosed volcanicsedimentary series; the other is a high-temperature and high-pressure metamorphio belt represented by eclogite, which is distributed on the northwestern side and consists mainly of late Archean-early Proterozoic crystalline basement. With similar metamorphic ages, the two high-pressure belts are in faulted contact. There exists a relatively pronounced metamorphic break between them. They were formed at 0.7—1.4 GPa and 350—560℃ and at≥2.8 GPa and 680—840℃, respectively. The formation of the paired, high pressure metamorphic belts are related to the intracontinental subduction occurring between the North China and Yangtze plates. The subduction was directed from the Yangtze plate towards the North China plate. The high-temperature and high-pressure belt was subducted to a depth greater than 90 km and uplifted rapidly in the process of continuous subduction and obduotion. The low-temperature and high-pressure belt was subducted to a depth of about 25—50 km and uplifted gradually to the Earth's surface owing to the isostatie balance after the decrease of the subduction speed and cease of the subduction. The establishment of the paired high-pressure belts is of major significance for solving the problem of the geodynamic evolution of the boundary of the North China and Yangtze plates.

关 键 词：变质岩 双高压 变质带 变质作用 

分 类 号：P588.3[天文地球—岩石学]