ELEMENTAL GEOCHEMICAL EVIDENCE FOR THE PETROGENESIS OF THE ZHUOXI QUARTZ-DIORITE, ZHEJIANG PROVINCE
浙江左溪石英闪长岩成因的元素地球化学证据

Zhuoxi quartz-diorite body, which is situated in the Shaoxing-Jiangshan deep fault zone, is composed of quartzdiorite, gneissic quartz-diorite, gneissic diorite, plagioclase-amphibolite and others. The average chemical composition is similar to that of the Proterozoic Shuangxiwu spitite-keratophyre, which is situated near the Zhuoxi body. The contents and ratios of elements in difterent lithologies of the body vary in a linear evolutionary relationship, as that in a imhomogeneous binary mixttre. The calculatiens to simulate the contents of lock-forming and rare earth elements indicate that the residual phase produced by a 50% partial melting of the Shuangxiwu group has a chemical composition almost the same as that of the pyroxene-plagioclase-amphibolite in the Zhuoxi body. The mixtures composed of the melting phase and the residual phase in different mixing percentages correspond to the different lithologies in the body. Therefore, the authors regard partial melting of Shuangxiwu group-inhomogeneous mixing of the melting phase and the residual phase as the suitable petrogenetic model to explain the elemental geochemistry of the Zhoxi quartz-diorite body.