【作者】 黄典豪； 聂凤军； 王义昌； 江秀杰；

【Author】 Huang Dianhao,Nie Fengjun and Wang Yichang (Institute of Mineral Deposits,Chinese Academy of Geological Sciences) Jiang Xiujie (No.13 Geological Party of Shaanxi Province)

【机构】 矿床地质研究所； 陕西省地质矿产局第十三地质队；

【摘要】 <正>前言陕西金堆城—黄龙铺地区钼矿资源丰富,既有早已著称于世的金堆城巨型斑岩钼矿床,也有近年来探明的石家湾大型斑岩钼矿床和黄龙铺大型碳酸岩脉型钼(铅)矿床,因而该地区构成了东秦岭近东西向展布的钼多金属成矿带的重要组成部分。我们在研究黄龙更多还原

【Abstract】 Jinduicheng-Huanglongpu area lies within the Yushan faulted-upwarping area on the southern edge of the Sino-Korean Paraplatform.The Yenshanian granitoids（124 to 130m.y.）,which are most developed in the area,seem to be associated with the porphyry type molybdenum deposits.The area is a part of the Eastern Qinling molybdenum-polymetallic metallogenetic zone.During the investigation of the Huanglongpu carbonatite vein-type Mo（Pb） deposit, the authors studied preliminarily geology and petrology of the Laoneushan rock body and Jinduicheng and Shijiawan porphyry masses. The Laoneushan rock body was emplaced in gneiss of Archaean Taihua Group and meta-spilite of Proterozoic Xionger Group.It is about 400 km² in size.The Jinduicheng granoporphyry was emplaced in meta-spilite of Xionger Group.Shijiawan granoporphyry was intruded into meta-spilite of Xionger Group and meta-silicarenite as well as quartzite of Gashanhe Formation. These porphyries are less than 1 km² in size. Petrological studies show that these granitoids are similar in mineral assemblage, though different in mode of occurrence.In addition to quartz,there are K-feldspars consisting of microcline,intermediate microcline and orthoclase, whose degree of order（δ） ranges from 0.92 to 0.16.Plagioclases are chiefly oligoclase（An 24-14） and albite,with degree of order being 0.84—0.40.Biotitebelongs to eastonite and accessory minerals include zircon,magnetite, apatite,orthite,molybdenite,pyrite etc.According to assemblage of the accessory minerals,the granitoids are considered to be of magnetite-apatitezircon type.Petrochemically,these granitoids are characterized by 74.5 to 70.96 percent SiO₂,and 9.93 to 7.73 percent K₂O+Na₂O（K₂O>Na₂O）.Their acidities,contents of alkali-metals and aluminium are higher than the average values of all granites in the world. The Sr and Pb isotopic compositions of the Laoneushan monzonitic granite and the Jinduicheng and Shijiawan granoporphyries indicate that （87）Sr/⁸⁶Sr ratios of the accessory mineral apatite of the rock bodies range from 0.7059 to 0.7087,averaging 0.709.Lead isotopic composition（whole rock sample） of the Laoneushan monzonitic granite are 17.637 for ²⁰⁶Pb/²⁰⁴Pb,15.428 for ²⁰⁷Pb/²⁰⁴Pb and 37.910 for ²⁰⁸Pb/²⁰⁴Pb.Lead isotopic compositions（whole rock sample） of the Jinduicheng granoporphyry are 18.129 for ²⁰⁶Pb/²⁰⁴Pb, 15.511 for ²⁰⁷Pb/²⁰⁴Pb and 38.049 for ²⁰⁸Pb/²⁰⁴Pb. An analysis of the above data has led the authors to believe that the claim that the Laoneushan large rock body is of crustal remelting type while the Shijiawan and Jinduicheng small porphyries are of mantal differentiation type does not hold water;instead,all of these rock bodies are products of crystallization differentiation of deep-seated melted magma.These two granoporphyries seem to be"satellite-type"small rock bodies derived from the Laoneushan large body and are genetically related to the corresponding Jinduicheng and Shijiawan porphyry molybdenum deposits which are of hypothermal-mesothermal type formed through mixing of ore-bearing fluids from anatectic magma with meteoric waters under the acid reducing condition.更多还原