EARLY PRECAMBRIAN METAMORPHIC ROCKS AND EARLY EARTH CRUST EVOLUTION IN DAQINGSHAN, INNER MONGOLIA
Jin Wei Li Shuxun Liu Xishan(Department of Geology)
The early precambrian rocks in Daqingshan region can be divided into three lithological structural units, (1) granulite-charnockite unit; (2) hornblende gneiss-tonalite u-nite; (3) alumimum rich gneiss-kaligranite unit. Unit one is the oldest rocks in the region, which is at least older than late Archaean(2800Ma). Unit two belongs to late Archaean middle-low grade metamorphic rocks with the characteristics of granite -greenstone belt. Unit three is the rock association formed in early proterozoic orogenic metamorphism. Accordiny to the rearranged geological event diagram, some questions about early crust evolution of this region have been discussed in this paper.