东天山双龙铜矿石英闪长岩锆石U-Pb定年、Hf同位素分析及对构造环境的制约

通过对新疆东天山雅满苏岛弧带双龙铜矿成岩地质特征、岩石地球化学特征及Hf同位素分析,认为赋矿岩体为一套形成于后碰撞环境下的准铝质高钾钙碱性岩石系列的石英闪长岩,LA-ICP-MS锆石U-Pb同位素年龄为(300.9±1.2)Ma。岩石地球化学显示,赋矿岩石具富集大离子亲石元素(LILE)K,Rb等及高场强元素(HFSE)Th,U,Zr和Hf,贫Nb,Ta,Ti,Sr,P特征,可能形成于后碰撞构造环境。石英闪长岩锆石176Hf/177Hf变化范围0.282949~0.283002,平均值0.282979,εHf(t)值为12.32~14.40,平均13.40,tDM2(Hf)为375~482Ma,平均429Ma,表明岩浆物源可能来自志留纪新生地壳的部分熔融。

Zircon U-Pb Dating,Hf Isotope Analysis and its Restriction on Tectonic Environment of the Shuanglong Copper Deposit in the Eastern Tianshan

Through the study of quartz diorite geological characteristics, rock geochemical characteristics and Hf iso- tope analysis of the Shuanglong copper deposit in Yamansu island area,it is concluded that the mineralized rock mass is a set of quartz dendrites formed in the series of quasi-aluminum high potassium calcium alkaline rocks in the post-colli- sion environment.Its LA-ICP-MS zircon U-Pb isotope age is (300.9 ±1.2) Ma(late Late Carboniferous), representing the crystallization age of magma.Through rock geochemistry analysis,it is concluded that the mineralized rocks have the characteristics of rich Cs, Rb, Ba and other large Ionic prostony elements, and high field strong elements Nb,Ta,Ti,Sr,P are obviously losing.The geochemical characteristics of the island arc magmatic rock may be formed in the post-collision tectonic environment. The variation of quartz diorite zircon 176Hf/177Hf ranged from 0.282 949 to 0.283 002 with an aver- age value of 0.282 979. The value of εHf(t) was 12.32~14.40, the average was 13.40, and the tDM2(Hf) was 375 ~ 482 Ma, the average was 429 Ma(middle Silurian), it is indicated that the source of magmatic material may come from the mixing of the Silurian strata.