中文摘要:金堆城花岗斑岩在燕山期侵位于元古代熊耳群变细碧岩中，按其岩石化学特征应属高硅富钾的钙碱性系列岩石。钼矿化发育于斑岩体及其外接触带内，矿体由含铟石英细网脉组成，最大矿化深度约达1000m。围岩蚀变自斑岩体向外为．钾化、绢（云）英岩化-硅化-青磐岩化，其中以硅化最为强烈且与钼矿化关系最密切。气液包裹体与含子矿物多相包裹体常常共存，主要成矿温度为300-400℃。硫、氧和碳同位素特征表明，主要成矿阶段的成矿流体是以岩浆水为主的混合液，硫、钼主要来源于花岗岩浆。低fO2、高fS2的弱酸性还原条件以及成矿流体沸腾是辉钼矿沉淀的主要因素。矿床成因类型属斑岩型中高温热液钼矿床。
Abstract:Situated in the Yushaan faulted-upwarping area on the southern edge of Sino-Korean Paraplatform, the Jinduicheng porphyry molybdenum deposit is the most important molybdenum mine being exploited on a large scale in China.During the Yanshanian orogeny there occurred tectono- magmatism, and the Jinduicheng granite porphyry was emplaced in metaspilite series of the Proterozoic Xionger Group, controlled by NW-trending fault. Its outcrop is 450 meters Jong and 150 meters wide, trending 3300 and dipping laterally in NW direction (Fig. l). Mineral compositions are mainly quartz (25-40%), microcline and microperthite (27-40%), and plagiocryse (An 8-14, 14-32%), associated with minor biotite and muscovite; phenocryst is made up of K-feldspar, quartz and plagloclase. Accessory minerals are of magmatite-apatite-zircon assemblage. The porphyry is characterized petrochemically by an average Si02 0f 73.83% and K2O+Na2O of 8.06% (with K2O/Na2O ratio being l.82), belonging to silicon-high, potassium-rich rock of calc-alkatite series. Mineralization occurs in the porphyry body and biotitized and hornfelsized spilite within the exocontact zone. The orebody consists chiefly of fine stockwork, which shows elliptic form in plan and has a length to width ratio of about four in cross section. The greatest depth of mineralization reaches 1000 meters below the surface (Fig.3). According to assemblage of ore and gangue minerals, veins in the ore deposit have been classified into five types: (1) pyrite-quartz veins, (2) pyrite-K-feldspar-quartz veins, (3) pyrite-molybdenite- quartz veins, (4) pyrite-molybdenite-K-feldspar-quartz veins and (5) muscovite -fjuorite- pyrite- molybdenite-quartz veins. As the most important economic molybdenum mineral, molybdenite occurs in impregnation, radioflake, thin film and veinlet forms in the veins, mainly possesses polytypes of 2H and mixture of 2H+3R, and has rhenium content ranging from 4.2 to 26ppm. Alterations of the wail rocks show grossly zonation of K-feldspathization- greisenization→silicification→propylitization from the porphyry outwards of these alterations, silicification is intense and has close relationship with molybdenum minerallization. Fluid inclusion studies yield homogeneous temperatures from 250℃ to 240℃, with the main ore-forming stage ranging from 400℃ to 300℃. Gaseous inclusions are frequently coexistent with multiphase inclusions containing such daughter minerals as halite, syjvite, molybdenite and K-feldspar. Under the condition of medium-high temperature, lower f02, high fS2, and weak acidity, the boiling of ore-forming fluids makes up a prerequisite for the precipitation of molybdenite. Isotope compositions of sulfur, oxygen and carbon suggest that the high temperature stage (450℃) mainly has magmatic water （δ18OSMOW= +9.4‰, δ34S = +4.5 ~ +5.4‰), and the main ore-forming stage (400-300℃, δ18OSMOW = +8.3 ~ +2.0‰, δ34S = +5.6 ~ +3.7‰) is characterized by mixture solution with magmatic water as the major source. In contrast, the late stage is noted for mixed solution dominated by meteoric water (250-240℃, δ18OSMOW = +4.8 ~ -1.6‰. It is therefore conceivable that sulfur and molybdenum are mostly derived from magmatic source. In conclusion, the industrial-genetic type of the studied deposit belongs to porphyry type medium-high temperature hydrothermal molybdenuum deposit whose metallogenetic model is outlined in Fig.4.
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黄典豪，吴澄宇，聂风军.1987.陕西金堆城斑岩钼矿床地质特征及成因探讨[J].矿床地质,6(3):22~34.1987.Geological Features And Origin Of The Jinduicheng Porphyry Molybdenum Deposit, Shaanxi Province[J].Mineral Deposits6(3):22~34
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