天山—蒙古—兴安变质地区的变质作用及地壳演化

本区属于西伯利亚地块和塔里木—中朝地块之间的古生代陆间地槽,经历了由活动—稳定—活化解体—再稳定的演化过程,可分为两大变质旋回。在前震旦纪变质旋回中,先后发生了太古期、早元古期和晚元古期变质作用,它们的热流值表现为由高到低的旋回性变化。在古生代变质旋回中,加里东期和华里西期变质作用广泛发育,它们的变质作用类型表现为多样性的特点,变质带则是具有由北部和南部边缘向内部迁移的现象。

Metamorphism and Crustal Evolution of the Tianshan-Mongolia-Hinggan Metamorphic Domain

The studied domain is located to the north of the North China and the Tarimalxa metamorphic domains, including most part of the Mongolia. As a Palaeozoic inter eontinental geosyncline, it is situated between the Siberia and the Tarim-Sinokorean massifs. The domain was subjected to the Arch.can and the Early Proterozoic regional dynamic heat flow metamorphism and Late Proterozoic regional low-temperature dynamic metamorphism successively during the P resirian period. It became a stable massif and probably combined with the south and the north massifs in the Late Proterozoic (about 800Ma). The dismembering and riftting of tire domain began in the Sinian period so pares of the domain was transformed from a stable massif into a moble geosyncline. From Sinian. to Cambrian, most part of the domain might be the stable upwarded district, only in tire north and the south, margins of the domain the Caledonia geosynclines was formed, then the domain began to converted into a mobile sea trench in a large area during the Ordovieian. It was subjected to regional low-temperature dynamic metamorphism or regional dynamic heat flow metamorphism during the period from Cambrian to the end of the Silurian period. The metamorphic types appear in greater differences in different places, including regional dynamic heat flow, regional low-temperature dynamic or buried metamorphism. The domain was transformed finally into stable massif and combined with the south and north massifs again due to the Variscan metamorphism during the Devonian-Late Permian.