新疆萨热克铜矿辉绿岩地球化学特征与动力学意义

Geochemistry Characteristics and Geodynamic Implication of Diabases in Sareke Copper Deposit, the Xinjiang Uygur Autonomous Region, China

萨热克铜矿的南矿带发育了大量的辉绿岩脉,本文针对地表和钻孔中采集的辉绿岩样品开展了岩石地球化学研究。结果显示,岩石w(Si O2)在40.36%~44.78%之间,w(TFe2O3)(全铁)和w(Ti O2)变化范围分别为7.19%~10.67%和2.28%~2.73%,呈现高钛、富碱和贫硅的演化趋势,属于高钛系列辉长(绿)岩类;稀土和微量元素具有与OIB相似的特征。萨热克辉绿岩岩石地球化学特征与托云盆地玄武岩极其相似,二者应为同源产物,形成于板内拉伸构造环境,可能与岩石圈拆沉作用有关,受控于印度-亚洲大陆碰撞的远程效应。

Sareke copper deposit, located in the Sarekebayi secondary basin of the Southwestern Tianshan Mountain, in the Xinjiang Uygur Autonomous Region, China, is a large scale sandstone type copper deposit recently exploited, which has attracted many geologists＇ focus, leading to great progress in economic geology research. It is noteworthy that a great deal of diabases occur in the south ore district; however, there is yet no systematic study on diabase dikes in the Sareke Basin. This research generally collected diabase samples from drill holes and outcrops, and carded out systematic petro-geochemistry research. Results reveal that diabase samples show evolutionary trend of rich in titanium and alkali, poor in silicon, which can be categorized as high titanium gabbro, with SiO2 contents varying from 40.36% to 44.78%, and the variation ranges of TFe203 and TiO2 of 7.19%-10.67%, 2.28%-2.73%, respectively. Primitive mantlenormalized trace element spidergrams and chondrite-normalized REE distribution patterns of samples show similar result with typical OIB. The petro-geochemistry characteristics of Sareke diabase is extremely similar to the basalt from the Tuoyun Basin, indicating that they were derived from the same source and formed in within-plate stretching tectonic settings, which can be related to the delamination of subcontinental lithosphere mantle, resulted from the remote compact of the Indo-Asian continental collision.