Geochemistry of Granitoid Rocks and Crustal Evolution, Zhejiang Province, China-Ⅱ. Proterozoic Granitoid Rocks

Proterozoic granitoid rocks in Zhejiang Province were formed in the Shengongian period (1. 8-1.9 Ga) and the Late Jinningian period (0. 6 -0. 9 Ga), respectively. Petrogenetic problems are discussed based on chemical (major, trace elements and REEs) and Nd-Sr isotopic compositions. The Shengongian granites resulted from partial melting of the Badu Groupand the Late Jinningian granites are of mantle dedvation with or without conednation of Crustalmaterial. The crust in Zhejiang had undergone three major periods of growth during 2. 6 - 2. 7Ga,0. 8 - 1. 1 Ga and 0. 10 - 0. 12 Ga after it was generated in Archean time. Compositional fractionation in the process of crust evolution is not evident. The presence of Late Jinningian granites of mantle- and man tie-crust-derivation along the JiangShan-Shaoxing Fault is indication ofcrust subduction at that time.