【作者】 周勇；

【导师】 李俊建；

【作者基本信息】 中国地质科学院 ， 矿物学、岩石学、矿床学， 2013， 硕士

【摘要】 三胜村钨钼矿床位于内蒙古集宁市化德县境内,是新近评价出的中型矿床,远景可达大型。本文在野外地质调研、矿床地质、岩相学、LA-ICP-MS锆石U-Pb和辉钼矿Re-Os年代学、元素地球化学、稳定同位素和流体包裹体的系统研究基础上,探讨了该钼多金属矿床成矿作用和成矿机制,建立了该钨钼矿床的成矿模式。赋矿的三胜村花岗岩具有高硅,富碱特征,为准铝质-弱过铝质和高钾钙碱性/钾玄岩系列的深源Ⅰ型花岗岩。这些花岗岩相对亏损Ba、K、Sr、P、Ti等元素,显示地幔来源。经LA-ICP-MS锆石U-Pb测年法新获得花岗岩成岩年龄137±1Ma,为早白垩世侵入体。赋矿地层三面井组砂岩、粉砂岩的轻重稀土分馏不明显,轻稀土轻度富集,重稀土走势平缓,并均出现K、P、Ti明显亏损。玛尼吐组安山玢岩轻重稀土分馏明显,轻稀土富集,重稀土分馏不显著。凝灰岩轻重稀土分馏不明显,曲线平缓。Eu均出现轻微富集。凝灰岩与安山玢岩均出现K、P、Ti强烈亏损。三胜村钨钼矿床矿体主要呈层状、似层状、透镜状产出,受岩浆岩和构造控制明显。矿石类型以石英脉型和细脉浸染状为主。根据矿物共生组合划分出了石英-黑钨矿,石英-辉钼矿-黄铁矿阶段和石英-碳酸岩三个成矿阶段。在辉钼矿-石英脉中主要见有三种流体包裹体,以富液相包裹体最为常见。主成矿阶段成矿流体温度集中在200～290℃之间,成矿流体成盐度为5.00～8.95wt%,密度为0.85～0.90g/cm3,对应成矿压力和成矿深度分别为6.12～16.49MPa和2.35-6.00km。矿石的铅同位素组成明显偏离地壳铅源区,成矿物质主要是来源于深源和造山带,这也与花岗岩源于深源的特征相吻合。采用辉钼矿Re-Os同位素定年新获得了三胜钨钼矿床的精确成矿年龄为138+1Ma,表明本区钼多金属矿床形成于早白垩世,与华北陆块北缘的主要钼矿床大规模成矿时间一致(140Ma)。这一年龄值在误差范围内与赋矿花岗岩的成岩年龄几乎等值(差值仅1Ma。)。表明花岗岩岩浆热液直接提供了成矿物质来源。三胜村钨钼矿的成矿模式为燕山晚期含矿热液侵位,在三胜村花岗岩体内、部分在三面井组砂岩、粉砂岩和玛尼吐组中酸性火山岩中、尤其在NNW向断裂构造裂隙中富集成矿。更多还原

【Abstract】 The W-Mo deposit of Sansheng village is located in Jining County, Inner Mongolia, which is a recent evaluation of medium-sized deposits, can go much further. Based on system research as follows:field geological investigation, mineral deposit geology, petrography, LA-ICP-MS zircon U-Pb and Molybdenite Re-Os chronology, element geochemistry, stable isotopes and fluid inclusions, this paper has discussed the molybdenum polymetallic mineralization and metallogenic mechanism, set up a metallogenic model of the W-Mo deposit. The granite bearing ore of Sansheng village is characteristics with high silicon, rich alkali, metaluminous to weakly peraluminous and high K calc alkaline/shoshonite series, indicates deep source of I type granite. The granite relative loss of Ba, K, Sr, P, Ti and other elements, show the mantle origin. The newly obtained LA-ICP-MS zircon U-Pb dating granite diagenetic age is137±IMa, early Cretaceous intrusive body. The ore-bearing sandstone and siltstone formation of Sanmianjing group show no obvious REE fractionation, slight enrichment of LREE, flat curve of HREE and there are K, P, Ti apparent loss. The andesitic porphyrite of Manitu group has a significant REE fractionation, enrichment of LREE, not obvious HREE fractionation. The tuff of Manitu group has a slight REE fractionation, which curve is flat. Eu appeared slightly enriched in both. Tuff and andesitic porphyrite show strongly loss of K, P, Ti. The Sansheng W-Mo ore body presents mostly stratiform, stratoid and lenticular formation, obviously controlled by magmatic rocks and structures. Vein type in the quartz and veinlet are the main ore types. According to the mineral assemblages we can divide into three stages of mineralization, quartz-wolframite stage, quartz-molybdenite-pyrite stage, quartz and carbonate stage. In the molybdenite-quartz veins there are mainly three types of fluid inclusions, which the rich liquid inclusions is most in common. Temperature of ore-forming fluid in main metallogenic stage is between200～290℃, the salinity of ore-forming fluid is5.00～8.95wt%, density of0.85～0.90g/cm3, the metallogenic pressure and metallogenic depth are6.12～16.49MPa and2.35～6.00km respectively. The lead-isotope composition of ore deviates significantly from the crust, the metallogenic substance mainly derives from deep source and orogenic belt, which also coincides with that granite derived from the deep source. The newly obtained accurate Re-Os dating of Molybdenite for metallogenic age from Sansheng W-Mo deposit is138±1Ma, shows that the area of molybdenum polymetallic deposits formed in the early Cretaceous, is in line with the main molybdenum deposits in the northern margin of North China block of large scale mineralization time (140Ma). This data of age almost equivalent to granite rock and ore within the error (the difference is only1Ma.), shows that the granite magma hydrothermal directly provides the source of metallogenic material. Sansheng W-Mo deposit metallogenic model presents as follows:in the late Yanshan phrase hydrothermal ore bearing solution took emplacement, in Sansheng granitic pluton and partly in sandstone, siltstone of Sanmianjing group and acidic volcano rock of manitu group, especially enriched in NNW fault forming tectonic fissures.更多还原