青海昆仑河北地区岩浆活动、金矿成矿特征及找矿前景分析

青海昆仑河北地区靠近昆中断裂带，经历早古生代、晚古生代—中生代多期岩浆活动，近年来自西至东陆续发现黑海北、拉陵灶火、苏海图、加祖它士西、向阳沟、加祖它士东、大灶火、黑刺沟等多个金矿床（点），形成一条东西长度近150 km长的成矿带。文章在总结带内金矿成矿基本特征基础上，选取黑海北金矿和加祖它士东金矿的赋矿围岩开展锆石U-Pb定年，结果显示黑海北硅化二长花岗岩锆石206Pb/238U加权平均年龄为443±8 Ma，形成于原特提斯洋向柴达木地块俯冲碰撞后伸展环境；加祖它士东的花岗闪长岩脉含有较多的继承锆石，锆石206Pb/238U加权平均年龄为250±1 Ma，继承锆石206Pb/238U加权平均年龄为420±2 Ma，加祖它士东花岗闪长岩侵位于古特提斯洋向北俯冲背景下的大陆弧构造环境。综合分析认为昆仑河北地区金矿成矿作用与早中生代三叠纪岩浆活动关系更为密切，其矿床类型存在造山型金矿与岩浆热液型金矿两种不同认识。昆仑河北地区土壤化探异常、低阻高极化激电异常、主要断裂（穿矿区）的次级断裂形成的蚀变破碎带等可以作为区内主要的找矿标志，推测该成矿带具有较大的找矿前景。 

Magmatism, metallogenic characteristics, and prospecting prediction for gold deposits in the north of Kunlun River area, Qinghai, China

The north of Kunlun River area, which is close to the central Kunlun Fault Zone, has experienced multi-stage magmatic activities of early Paleozoic and Paleozoic-Mesozoic. A number of gold deposits (occurrences) have been discovered successively in this area for the past few years from west to east, such as Heihaibei, Lalingzaohuo, Suhaitu, Jiazutashixi, Xiangyanggou, Jiazutashidong, Dazaohuo and Heicigou, forming a metallogenic belt with an EW-length of nearly 150 km. In consideration of the basic characteristics of gold deposits in the belt, the ore-hosting wall rocks from the Heihaibei and Jiazutashidong gold deposits were selected to carry out zircon U-Pb dating in this study. The results show the silicified monzonitic granites from the Heihaibei deposit yield zircon weighted mean ²⁰⁶Pb/²³⁸U age of 443±8 Ma, which should be formed under the stretching environment after the collision of the Proto-Tethys Ocean to the Qaidam block. The diorite dikes from the Jiazutashidong deposit, which bears more inherited zircon, yield the zircon weighted mean ²⁰⁶Pb/²³⁸U age of 250±1 Ma and 420±2 Ma for primary zircon and inherited zircon, respectively, indicating a continental arc tectonic setting under the northward subduction of the Paleo-Tethys Ocean during the emplacement of diorites. Overall, it is believed that the gold mineralization in the northern Kunlun River area is more closely related to the Early Mesozoic Triassic magmatic activity, but opinions vary about the deposit types on whether it belongs to the orogenic or magmatic hydrothermal. Soil geochemical anomalies, low-resistance and high-polarization IP anomalies, and altered fracture zones formed by secondary faults can be used as the main ore prospecting markers in the northern of Kunlun River. It is considered that this metallogenic belt has good prospects for gold deposits.