东昆仑东段阿斯哈矿床石英闪长岩LA-ICP-MS锆石U-Pb定年及岩石地球化学特征

阿斯哈石英闪长岩体位于东昆仑中央隆起带，侵入于古元宇金水口岩群中。岩体内产有阿斯哈大型金矿床，石英闪长岩与该区金矿形成具有密切的时空关系。采用锆石LA-ICP-MS、XRF和ICP-MS对石英闪长岩进行了定年以及地球化学测定。研究表明：该区石英闪长岩属钙碱性准铝质岩石，具有I型花岗岩的特征；其成岩年龄为（238.4±1.4） Ma；岩体稀土配分曲线几近一致，显示为同源岩浆演化特点，均表现出轻稀土相对富集的右倾特征，Eu具有弱的负铕异常；岩体明显富集大离子亲石元素，亏损高场强元素；具有明显的“TNT”负异常，显示出安第斯型岩浆弧火成岩构造属性；岩石Rb/Sr和Nb/Ta值介于地壳和地幔之间，并广泛发育暗色微粒包体，表明岩浆的壳幔混合成因。综上所述认为：阿斯哈金矿床石英闪长岩具有I型花岗岩特征，形成于印支期，具有壳幔混合的特征。

LA-ICP-MS Zircon Dating and Geochemical Characteristics of Quartz Diorite in Asiha Gold Deposit in East Segment of the Eastern Kunlun

The Asiha gold deposit is located in the eastern Kunlun uplift belt, and intrudes Jinshuikou Group in Proterozoic. The quartz diorite has closely spatio and temporal relationship with the gold mineralization in this area. The authors adopted LA-ICP-MS zircon dating, XRF and ICP-MS analysis for geochemical characteristics of the quartz diorite. The reasearch results indicate that the quartz diorite belongs to the calc-alkaline and metaluminous I type granite. The emplacement age of the intrusion is (238.4±1.4) Ma. REE patterns of different samples are basically in accordant, showing their comagmatic evolution. The quartz diorite is comparatively rich in LREE, with weak negative Eu anomalies, remarkably enriched in LILEs, depleted in HFSEs, with negative anomaly about TNT, which are similar to those of ligneous rock in Andean type continental margins. The fact that the values of Rb/Sr and Nb/Ta are between those of the crust and mantle, combined with widespread mafic microgranular enclaves, shows that the magma was derived from crust-mantle mixing source. In summary, the quartz diorite has the characteristics of I-type granite, formed in Indosinian, with crust-mantle mixing characteristics.