EARLY PRECAMBRIAN METAMORPHISM,DEFORMATION AND CRUSTAL EVOLUTON IN THE DAHUANGGOU-BANSHIGOU AREA,SOUTBERN JILIN

In the earliest Middle Archean supracrustal rocks were formed.Then amphibolite faciesn1etamorphism happened at 2.605 Ga B. P. Later tonalite was intruded,accompanied by duc-tile shear deformation. In the Late Archean supracrustal rocks and tonalite underwent low am-phibolite facies metamorphism around 2.538 Ga B.P. and later there occurred an event of NE-directed ductile shear deformation. In the Early Proterozoic,K-feldspar granite was intrudedand then it underwent greenschist facies metamorphism at about 2.380 Ga;besides there alsooccurred two events of NW and NE shear deformation. The above three phases are character-ized by different mineral assemblages and shear deformations of different directions and scales.