西天山卡特巴阿苏金铜矿区中性侵入岩地球化学特征及地质意义

Geochemical Characteristics and Geological Significance of Neutral Intrusive Rocks in Kateba’asu Au-Cu Deposit,Western Tianshan

卡特巴阿苏金铜矿矿区中性侵入岩研究表明,中性侵入岩的SiO2含量较高,稀土元素整体表现为LREE富集,HREE亏损的分馏模式,微量元素总体显示出亏损Nb、Ta、Ti等高场强元素,富集Rb、Ce、Ba、Th等大离子亲石元素。三类中性侵入岩成因无明显的联系,为不同源成岩,属于晚石炭世混源序列,兼具原始地幔和岛弧火山岩的特征,岩石由遭受消减板片流体交代地幔源区部分熔融形成,兼具板内玄武岩和火山弧玄武岩的构造特征,为强烈的大陆裂谷伸展作用的产物。对全岩矿化闪长岩锆石 U-Pb 测试结果显示,闪长岩的侵位年龄为(305.0±2.0) Ma,为晚石炭世成岩,这与前人获得的载金黄铁矿(310.9±4.2) Ma的年龄在误差范围内一致,认为该矿床形成于造山后伸展环境之下,矿床深部可能存在与中性岩有关的斑岩型铜金矿体。

The study of neutral intrusive rocks in the Kateba’asu Au-Cu deposit ore mine shows that the content of SiO2 intrusive rocks is higher, and the REEs are characterized by LREE enrichment and fractional distillation of HREE loss. The trace elements generally show loss of high field strength elements such as Nb, Ta, and Ti,enriched in large ion lithophile elements such as Rb, Ce, Ba ,and Th. There is no obvious relationship between the three types of neutral intrusive rocks, which are different source rocks and belong to the late Carboniferous mixed source sequence, which is characterized by both the original mantle and the island arc volcanic rocks. The rocks are partially melted by the reduction of the mantle source zone , both the structural characteristics of intraplate basalts and volcanic arc basalts are the products of strong continental rift extension. The zircon U-Pb test results of the whole rock mineralization diorite reveal that the emplacement age of the diorite is (305.0 ± 2.0) Ma, which is the late Carboniferous diagenesis, which is similar to the previous gold-bearing pyrite (310.9 ± 4.2) Ma. The age is consistent within the error range. It is believed that the deposit is formed in the post-orogenic extension of the environment, and there may be associated with the Neoproterozoic porphyry copper-gold ore body.