阿勒泰西南缘珠万喀腊铜矿杂岩体特征及找矿意义

位于阿尔泰西南缘的珠万喀腊杂岩体,产于珠万喀腊二叠纪陆相火山岩盆地,侵入地层为下二叠统哈尔加乌组和卡拉岗组,主要由闪长岩相和辉长岩相组成,二者呈侵入接触关系。其中闪长岩相存在三个过渡的岩相带:中心相闪长岩,过渡相辉石闪长岩及边缘相蚀变闪长岩。辉长岩相发现辉石岩、蛇纹岩、黄铜-磁黄铁矿化橄榄岩。地球化学特征表明,SiO2含量总体较低,为47.14%～55.90%,为中基性岩石。K2O+NaO变化范围1.27%～6.99%,岩石为碱性岩石系列。稀土元素丰度在131.1×10-6～159.7×10-6之间,属富集REE。LREE/HREE比值为2.87～3.52,属轻稀土富集型。微量元素总体富集大离子亲石元素(LILE),相对亏损高场强元素(HFSE),显示了岛弧岩浆的一些特点,可能是岩浆岩源区保留有早期俯冲的洋壳。EH4测量结果表明杂岩体内存在层状低阻异常带,可能为含矿岩相。岩体下部(距离地表700～800m处)可作为进一步找矿的有利部位。

Feature and prospective significance of the complex in Zhuwankala copper deposit,southwestern margin of Altay Mountain.

Zhuwankala complex located in the Permian continental volcanic basin in southwestern margin of Altay Mountain. It consists of diorite and gabbro lithofacies with intrusive contact, which host by Lower Permian Haerjiawu Formation and Kalagang Formation. The diorite lithofacies include three transition lithofacies belts: Centre facies diorite, transition facies pyroxene diorite and margin facies alteration diorite. In the gabbro lithofacies have found the pyroxenite, serpentinite, peridotite which contains chalcopyrite and pyrrhotite. Geochemical analysis of the complex show low content of SiO₂ , range from 47.14% to 55.90%, belong to middle to basic rock, and the K₂O+NaO contents from 1.27% to 6.99%, is alkaline rock series. The complex contents high REE from 131.1×10^-6 to 159.7×10^-6, and shows LREE-rich patterns of chondrite-normalized, with the LREE/HREE ratio from 2.87 to 3.52. All rocks are obviously enriched in large-ion lithophile elements (LILE) and relatively depleted in high field strength element. The magma displays some features of island arc magma, may be drivered from the previous subducted ocean crust. The complex is include a layered anomaly in 700~800m depth from the surface by EH4 measurement, may be a mineralization lithofacies as a fine exploration target.