GEOCHRONOLOGICAL EVIDENCE OF U-Pb FOR THE DAPANDAO ROCK FORMATION OF DONGXING GROUP IN JIAMISI BLOCK

In order to identify the formation age and geological background of the Dapandao rock formation of Xingdong rock group in central Jiamusi block in Shuangyashan area, Heilongjiang Province, the authors analyze the major elements of the formation. The results indicate that the metamorphic rocks in this area are chemically characterized by aluminum enrichment. The protolith are possibly sandstone, argillite, silicalite and dolomite with intermediate-basic volcanic rocks, belonging to island arc and low-K tholeiite series. The tectonic environment might be active island arc and continental margin. The zircon LA-ICP-MS U-Pb dating result for the garnet sillimanite feldspar gneiss of Dapandao formation shows that the volcanic rock of Xingdong rock group in the Jiamusi block should be more than 1000 Ma. Therefore the Dapandao rock formation was formed in the Meso-Neoproterozoic Era.