Abstract: The Qianjin magmatite in the Yichun area is located in the central part of the Yichun-Yanshou metallogenic belt which is rich in polymetallic mineral resources of Mo,Cu,Pb,Zn, Ag. The magmatite in the area consist mainly of granite, monzonitic granite, syenogranite and acid volcanics. Petrtochemically, the igneous rocks in the magmatite are characterized by enrichment in alkaline, potassium and aluminium, poor Mg and Fe, suggesting remarkable crystal differentiation. With rather high REE and LREE contents, obviously depleted in Eu, it is suggested that this late Mesozoic magmatite in the Qianjin area was formed at postorogenic stage of rapid lithospheric extension by resultative remelting of calc-alkaline and high-K cal-alkaline crustal rocks. Furthermore, the genesis, structure and mineralization of the Qianjin magmatite are discussed. It is suggested that the formation of the polymetallic deposits in the area might have been controlled by the magmatic activities in the area.

Key words: magmatite, geochemical characteristics, remelting of the crust, post-orogenic stage, Qianjin area, Yichun