文章摘要
杨宗锋.东秦岭尚古寺斑岩钼矿地质特征及 成矿潜力分析[J].地质与勘探,2011,47(6):1077-1090
东秦岭尚古寺斑岩钼矿地质特征及 成矿潜力分析
Geological Characteristics and Prospecting Potential of theShanggusi Porphyry Molybdenum Deposit in the East Qinling
投稿时间:2010-09-26  修订日期:2011-04-06
DOI:
中文关键词: 东秦岭 尚古寺 斑岩钼矿 岩石结构构造 成岩成矿物理过程
英文关键词: East Qinling, Shanggusi, porphyry molybdenum deposit, textures and structure, physical processes of diagenesis and mineralization
基金项目:河南省地质矿产重大科技攻关计划项目(26417)资助
作者单位
杨宗锋 中国地质大学地质过程与矿产资源国家重点实验室,北京 
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中文摘要:
      [摘 要]尚古寺斑岩钼矿位于东秦岭,为东秦岭地区已知钼矿区的最东部端元。出露面积约1.5km2 ,围岩主要为元古代片麻岩和碱流岩。辉钼矿化主要发育在花岗斑岩体的东部和南部区域,花岗斑岩顶部细粒花岗斑岩和其上覆花岗质伟晶岩均呈浸染状矿化,南部角岩发育裂隙矿化。花岗斑岩主体岩性主要矿物组合为石英、钾长石和斜长石,显示具有富硅、富碱和贫铁、贫镁的特征。花岗斑岩含有典型的圆粒状高温石英斑晶,其边部或整体呈现溶蚀吸回特征,溶蚀残余石英以港湾状、骨骸状和枝状为主,溶蚀部分被基质矿物充填或整体被钾长石和斜长石包裹,是高温花岗斑岩岩浆经历深部高温石英结晶后迅速就位浅部,发生快速不平衡结晶作用的产物。岩体内部发育中基性暗色微粒包体,呈球状、椭球状和塑性流动状态;富云母区域,呈不规则状和纹层状,暗示存在岩浆混合/ 混杂作用;蚀变晶洞构造、连通晶洞构造、空腔构造、硫化物蚀变突起和纵向蛇曲状云母富集区,记录了花岗斑岩内部流体出溶和运移的现象。花岗斑岩顶部过冷结晶形成的细粒花岗斑岩外壳,和其过冷前锋快速形成的花岗质伟晶岩圈闭了成矿流体,形成浸染状矿化。尚古寺斑岩钼矿是壳源岩浆和深部成矿流体耦合成矿的实例,对应于透岩浆流体成矿体系中的正岩浆成矿亚体系和边缘伟晶岩成矿亚体系,因而斑岩内部未出露部分可能依然具有巨大的成矿潜力。
英文摘要:
      Abstract:The Shanggusi porphyry molybdenum deposit is located in the easternmost part of all the known molybdenum deposits in the East Qinling with an outcrop area about 1.5km2. Disseminated molybdenite mineralization occurred in the marginal fine-grain porphyry granite and the periphery granitic pegmatite in the east and south part of the Shanggusi granite porphyry, and some fracture-filling molybdenite mineralization occurred in the hornstone of the southern Shanggusi granite porphyry as well. The main rock-forming mineral phase assemblage of the Shanggusi molybdenum-bearing granite porphyry contains quartz, alkaline feldspar and plagioclase, and the chemical compositions of the granite porphyry are characterized by enriched silicon and alkali, depleted iron and magnesium. The Shanggusi granite porphyry bears the typical high-temperature granular quartz, of which different extents of resorption have taken place with features of harbour-like, skeletal, and dendritic quartz. The dissolved quartz is filled with or included by alkaline feldspar and plagioclase, resulting from the fast disequilibrium crystallization after the high-temperature quartz-bearing granitic porphyry magma rapidly intruded at shallow levels. The spherical, ellipsoidal and plastic flow state of the mafic magmatic enclaves, and irregular, lamellar-shaped biotite-enriched regions in the porphyry body are compelling evidence for the magmatic mixing/ mingling. Fluids exsolution and transportation phenomenon are well preserved by some significant structures in the Shanggusi porphyry, including (but not limited to) the alteration miarolitic cavities, interconnected miarolitic cavities, cavities, the sulfide alteration prominence and the vertical snake-curved mica-enriched regions. The fine-grained granite porphyry and the granitic pegmatite, generated by the undercooled crystallization of the marginal porphyritic magma and rapid crystal growth of its front supersaturated melts respectively, by which the ore-forming fluids were trapped, resulted in the disseminated mineralization. The Shanggusi porphyry molybdenum deposit provides a coupled mineralization example of crust-derived magma and deep ore-bearing fluid, which correspond to the orthomagmatic subsystem and peri-pegmatite subsystem in the metallogenic system of transmagmatic fluid theory. Therefore, a large ore deposition may exist within the unexposed portion of the Shanggusi porphyry body.
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