辽宁猫岭大型金矿床成岩成矿年龄及同位素地球化学特征  

Geochronology and isotopic geochemistry characteristics of the Maoling large gold deposit, Liaoning Province, China

作　　者：刘军[1] 李铁刚 段超[1] LIU Jun;LI Tiegang;DUAN Chao(MLR Key Laboratory of Metallogeny and Mineral Assessment/Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质科学院矿产资源研究所/国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《地质通报》2018年第7期1325-1337,共13页Geological Bulletin of China

基　　金：国家重点研发计划项目<燕山期陆缘岩浆成矿作用及其深部过程>(编号:2017YFC0601403);中国地质科学院基本科研业务费项目<辽东白云金矿床成因及其成矿动力学背景>(编号:YYWF201512)

摘　　要：猫岭矿床是华北克拉通北缘重要的含砷浸染型金矿之一,赋存于元古代辽河群变质岩中。矿体以脉状、似层状、透镜状等产出,受NE向和NW向韧性剪切带及次级断裂控制。选取猫岭矿床10件硫化物样品开展了Rb-Sr定年,获得Rb-Sr等时线年龄为2287±95Ma(MSWD=1.9),初始Sr同位素比值I_(Sr)=0.7117,显示成矿作用发生于古元古代早期。矿区内卧龙泉和猫岭岩体的LA-ICP-MS锆石U-Pb年龄分别为183.0±1.8Ma、128.8±1.6Ma,表明晚中生代岩浆活动与猫岭金矿化无成因联系。成矿流体的δ^(18)O_W值为6.3‰~9.7‰,δD_W值为-97.2‰^-82.6‰,表明成矿流体主要来源于岩浆热液,混合部分大气降水。金属硫化物的δ^(34)S值为+4.3‰^+10.5‰,平均值为+7.9‰,与辽河群盖县组的硫同位素组成相似,表明硫源区为古元古代盖县组。猫岭矿床形成于古元古代伸展构造背景,与辽河群早期的同构造岩浆-热液活动有关,同期形成的强硅化圈保护金矿体免受后期地质作用的破坏。The Maoling large gold deposit, located in northern North China Craton, is an As-bearing disseminated gold deposit. The ore bodies are hosted in the metamorphic rocks of the Proterozoic Liaohe Group. The gold orebodies appear as veins, bedded, and lenticular, and controlled by NE-and NW-striking ductile shear belts and secondary faults. We present Rb-Sr ages from ten metallic sulfide samples which reveal the mineralization timing of the Maoling gold deposit as 2287±95Ma （MSWD=1.9）, initial Sr isotopic value ISr=0.7117. The high precision LA-ICP-MS zircon U-Pb dating method has been applied to measure the ages of the Wolongquan and Maoling granitic intrusions in the Maoling deposit, corresponding the dated ages of 183.0±1.8Ma, 128.8±1.6Ma, respectively. The Late Mesozoic magmatic activities were not related to the formation of the Maoling deposit. The calculated δ18O water values of ore-forming fluids show a range of 6.3‰ to 9.7‰. The δD values range of -97.2‰ to -82.6‰. H-O isotopic data indicate the ore-forming fluids were mainly derived from magmatic fluid with minor metoric water. The δ34S values recorded in the sulfide minerals from the Maoling deposit show a range of ＋4.3‰ to ＋10.5‰, averaging ＋7.9‰, similar to sulfur isotopic composition of the Gaixian Formaiton of the Liaohe Group. This evidence shows sulfur derived from strata of the Gaixian Formation. The Maoling gold deposit was formed in Paleoproterozoic extensional setting. The gold mineralization could be related to syntectonic magmatic hydrothermal activities in the early formation process of the Liaohe Group, and was not destroyed by later geological activitions as protection of contemporaneous strong silicfication belt.

关 键 词：锆石U-PB定年 硫化物Rb-Sr定年 同位素地球化学 猫岭金矿 辽东半岛 

分 类 号：P618.51[天文地球—矿床学] P597.3[天文地球—地质学]