新疆哈勒尕提铜铁矿床的成矿年代学研究

首次采用锆石SHRIMP微区U-Pb测年技术，对新疆西天山哈勒尕提铜铁多金属矿床成矿岩体进行了年代学研究，通过对角闪石黑云母二长花岗岩中单颗粒锆石12个样品点的分析，获得²⁰⁶Pb/²³⁸U年龄介于362.7~381.7 Ma，加权平均值为（367.3±2.2）Ma，表明岩体的结晶年龄为晚泥盆世。通过ICP-MS法测定了哈勒尕提铜铁多金属矿床中的辉钼矿Re-Os同位素年龄，获得其模式年龄的加权平均值为（370.1±2.4）Ma，等时线年龄为（371±12）Ma，代表了哈勒尕提铜铁多金属矿床的成矿年龄。两种测年方法获得的年龄在误差范围内基本一致，因此该测试结果表明哈勒尕提铜铁多金属矿床与晚泥盆世角闪石黑云母二长花岗岩侵入作用密切相关，角闪石黑云母二长花岗岩为哈勒尕提铜铁多金属矿床的形成提供了成矿物质和热源。

Zircon SHRIMP U-Pb and molybdenite Re-Os dating of Halegati Cu-Fe polymetallic deposit in West Tianshan Mountains and its geological implications

The first high-precision dating of the mineralization and rock-forming process in the Halegati Cu-Fe polymetallic deposit of West Tianshan Mountains was conducted in this paper. The zircon SHRIMP U-Pb dating of the Halegati Cu-Fe polymetallic deposit yielded a group of ages, in which 12 analyses presented ²⁰⁶Pb/²³⁸U concordant ages from 362.7 Ma to 381.7 Ma, with a weighted mean age of (367.3±2.2) Ma, which suggests that the crystallization epoch of the rock body is late Devonian. In addition, the ¹⁸⁷Re and ¹⁸⁷Os values of molybdenite from the Halegati Cu-Fe polymetallic deposit were determined by inductively coupled plasma mass sperctrometry (ICP-MS), with analytical errors of Re and Os between 0.04 and 0.56. The results show that the Re-Os model ages of the deposit are between 368.7 Ma and 384.6 Ma, the weighted average of model ages is (370.1±2.4) Ma,and the isochron age is (371±12) Ma. The authors obtained the same age from the two kinds of methods, which should represent the ore-forming age of the Halegati Cu-Fe polymetallic deposit, and it indicates that the rock-forming age is almost identical with the ore-forming age. The test result suggests that the Halegati Cu-Fe polymetallic deposit was closely related to the intrusion of late Devonian Hornblende biotite adamellite, and the hornblende biotite adamellite had close connection with metallogeny and provided metallogenic materials and heat for the Halegati Cu-Fe polymetallic deposit.