青海东昆仑鸭子沟多金属矿的成矿年代学研究

鸭子沟多金属矿是近年来青海省地质调查院在东昆仑祁漫塔格地区发现的一个具有斑岩型成矿特点的矿床。本文利用SHRIMP 锆石UPb和辉钼矿ReOs同位素对含矿斑岩体和矿石进行了精细成岩成矿时代测定，获得钾长花岗斑岩的SHRIMP锆石UPb年龄为224.0±1.6 Ma（n=15，MSWD=1.2），矿石的辉钼矿ReOs等时线年龄为224.7±3.4Ma（n=11，MSWD=2.7），成岩与成矿的时间一致，正好属于印支晚期东昆仑地区发生强烈壳幔相互作用并导致产生大量岩浆热液活动和成矿作用的时期。钾长花岗斑岩与矿床具有密切的时空和成因联系，斑岩体在时空分布上与矿区内的闪长岩、辉绿玢岩及辉长岩等幔源脉体紧密相伴，推测同属壳幔相互作用的产物。成岩、成矿的年代学研究表明，矿床形成的地球动力学背景与东昆仑地区印支晚期的区域动力学背景相一致，同时区内具有较大的寻找斑岩型矿床的潜力。

Geochronological Study on Yazigou Polymetallic Deposit in Eastern Kunlun, Qinhai Province

The Yazigou polymetallic deposit, discovered recently by the Qinghai Geological Survey in the Qimantage area of East Kunlun Mountain, Qinghai Province, is characterized by porphyry type mineralization. The authors have conducted geochronological study on the samples from the ore bearing porphyry and orebodies by SHRIMP zircon U Pb and molybdenite Re Os dating, respectively. The zircon U Pb age for the K feldspar granitic porphyry is 224±1.6 Ma while the Re Os age of ore molybdenite is 224.7±3.4 Ma, suggesting that diagenesis and mineralization took place coevally with the intense crust mantle interaction in the East Kunlun orogenic belt in Late Indosinian. Meanwhile, the interaction between crust and mantle resulted in large scale magmatic hydrothermal activities and metallogeny. The K feldspar granitic porphyry is closely related to polymetallic mineralization and the mantle derived diorite, diabase and gabbro in the area both temporally and spatially. It is refered that that the magmatic intrusives mentioned above are all the products of the crust mantle interaction. Based on the geochronological study, it is proposed that the Yazigou deposit has the same geodynamical setting as the whole Eastern Kunlun orogenic belt in Late Indosinian. Meanwhile, the authors also point out that there are good potentials for porphyry deposit prospecting in the area.