德兴铜矿、银山铜铅锌矿床的岩浆岩岩石化学特征及其成岩成矿机理探讨

德兴斑岩铜矿和银山铜铅锌矿床位于江南古陆与钱塘坳陷之过渡带,赣东北深大断裂的北西盘。德兴斑岩铜矿与燕山期(169Ma)浅成花岗闪长斑岩侵入体具有成因联系,侵入体属低硅钠质组合,铝质参数AA=Al-(K+Na+2Ca)]值变化于-13—93,表现为铝次饱和到不饱和特征,镁铁质参数B(B=Fe+Mg+Ti)值变化于100—265,二者构成负斜率岩浆演变趋势线,表明岩浆起源于上地幔或下地壳。银山矿床的形成与燕山期(145—142Ma)陆相火山一次火山岩系有关,其属高硅钾质火山岩组合,铝质参数A值变化于7—17

PETROCHEMISTRY AND PETROGENESIS OF THE MAGMATIC ROCKS OF THE DEXING COPPER AND YINSHAN Cu-Pb-Zn MINES AND ORE-FORMING MECHANISM OF THE RELATED ORE DEPOSITS

The Dexing porphyry copper deposit and the Yinshan Cu-Pb-Zn deposit occur to the northwest of the northeastern Jiangxi deep fracture, in a transitional zone between the Jiangnania oldland and the Qiantang depression. The Dexing porphyry copper deposit is genetically re'ated to the Yanshanian hy-pabyssal granodiorite porphyry intrusion (169 Ma), The intrusion is of low-Si sodic magmatic association. Its aluminian parameter AA=Al- (K + Na+ 2Ca)] ranges from -13 to 93, exhibiting the feature of alumina-subsaturation to - unsaturation, and the mafic parameter B (B=Fe + Mg + Ti) ranges from 100 to 265. The functional relation between both displays a trend line of magma-tic evolution with a negative slop, suggesting that the magma originated from the upper mantle or lower crust. The formation of the Yinshan deposit is related to the Yanshanian (145-142 Ma), continental volcanism-subvolcanism, i. e. related to a complete old volcanic apparatus consisting of rhyolitic and dacitic agglomerates, volcanic breccias and tuffs with transitional rock types as well as subvolcanic rocks such as dacite and quartz porphyry formed in the late stage of the volcanic cycle. The volcanic series that is characterized by high Si and K contents has its aluminuian parameter A varying from 7 to 176 and the mafic parameter B from 60 to 120, which show a trend line of magmatic evolution with a positive slope, indicating the magma resulted from anatexis of the sialic crust.The REE and trace elements such as Cu, Pb, Zh, Cr, Ni,Co and U of the magmatic rocks in the two districts are similar in characters,but the contents of Rb and Sr of the magmatic rocks in the Dexing district are consistent with average contents of diorite from Vinogladov (1962),and in the Yinshan district with one of granite.