【作者】 韩海涛；

【导师】 刘继顺；

【作者基本信息】 中南大学 ， 矿产普查与勘探， 2009， 博士

【摘要】 温泉钼矿位于甘肃省武山县温泉乡境内,系甘肃有色地勘局于2000年发现的一个具有大型前景的斑岩型钼矿床。本文以该矿床为研究对象,以区域成矿学和找矿系统工程学为指导,以花岗岩地球化学与成矿关系为研究切入点,以岩浆-构造-流体-成矿为主线,研究成矿地质条件、矿床地质特征、地球化学特征、成矿机制和成矿规律等,建立成矿模式,开展成矿预测。取得的主要成果与认识如下:1、以往地质工作表明,中央造山带（大别-秦岭-祁连-昆仑）内的钼矿资源,与花岗质岩石有关,且成型钼矿床均局限于东秦岭地区,构成了约占全国钼总储量52%的斑岩型钼矿带,系仅次于美国西部Climax-Henderson的全球第二大钼矿带。然而,2000年温泉钼矿的发现,打破了秦岭钼矿带的分布格局,不仅使其向西延展了400多公里,而且为整个中央造山带钼矿的寻找,指明了方向。2、温泉钼矿产于温泉花岗岩基内,受控于陈家大湾细粒黑云二长花岗斑岩株的内外接触带及其裂隙系统,系全岩矿化的斑岩型钼矿。2007年6月结束的陈家大湾15线至32线（0.3km²）,的详查工作,探获钼矿石量7805WT(0.053×10^-2)。外围260km²的温泉岩体内尚发现有42个钼矿（化）点,展示了大型钼矿的勘查潜力。3、温泉花岗岩基主要由中粒似斑状二长花岗岩所组成,侵入于中下元古界秦岭群高绿片岩相火山-沉积变质岩系、下古生界李子园群中低绿片岩相火山-沉积变质岩系和中上泥盆统李坝群-大草滩群碳酸岩、砂岩和页岩中。并受控于宝鸡～天水～临夏断裂带（南侧）与隐伏的武都～天水深大断裂（西侧）的结点部位。温泉钼矿的含矿岩体则系温泉岩基的补体—陈家大湾斑岩株,其侵位时代略晚于温泉岩基。成矿年龄为214±7.1Ma,大约为中生代三叠纪,处于印支运动期。4、目前经工程控制有34条矿体,单条矿体长50～650米,厚5～24.4m,顶面埋深38.5～5 16.5m。矿化类型有破碎带蚀变岩型、微裂隙石英脉-网脉型和浸染型。微细脉密集处即构成矿体,故矿体与围岩界线不清,需要化学分析方能圈定。矿石主要由辉钼矿、石英所组成,次为黄铁矿、黄铜矿、闪锌矿、白钨矿、毒砂、黝铜矿、方铅矿、斑铜矿、长石和云母等。围岩蚀变有钾硅化、硅化、沸石化、红色泥化等,青盘岩化不发育。5、含矿斑岩的SiO₂ 71.21%、K₂O4.91%、K₂O+Na₂O 8.22%,且K₂O大于Na₂O,里特曼岩系指数（σ）平均值为2.45,属于富钾（碱）的钙碱性岩石系列。这些特征与含钼斑岩（SiO₂ 70%～77%、K₂O+Na₂O8%～9%,且K₂O大于Na₂O）的特征极为相似,说明其钼成矿潜力良好。与花岗岩的维氏值相比,含矿斑岩的Mo、Cu、As、Ag元素明显富集,Bi、Hg、Ba、Au元素亏损,而Pb、Zn、Sb、Co、Ni、Cr、V元素大体与维氏值相当。其中Mo平均含量达45×10^-6,Cu达142×10^-6,表明含矿斑岩浆为钼成矿提供了物质来源。6、中粒似斑状二长花岗岩、细粒黑云二长花岗斑岩中稀土总量ΣREE为126×10^-6和148×10^-6;暗色包裹体中稀土总量最高,达167×10^-6;石英脉中仅为26.8×10^-6。这表明前三者为同源岩浆演化的产物,而石英脉与前三者稀土总量相去甚远,应为后期热液交代产物;LREE/HREE为4.5～5.6,（La/Sm）_N约为4.6,（Gd/Yb）_N为1.97～2.53,（La/Yb）_N为15.13～24.06,δEu值为0.66～0.68,δCe为0.83～0.90,上述数据表明:轻稀土富集,重稀土分馏程度明显偏低,花岗岩、石英脉、暗色包裹体稀土元素具有同源性,显示出地壳重熔再生花岗岩浆与幔汁混合特征。这也与微细粒镁铁质包体与基性岩墙共生现象相吻合。7、花岗质岩浆侵入作用是主要含矿断裂形成的动力学机制,其形成的断裂破碎带和节理裂隙系统为主要容矿构造。矿床成因模式为:印支期由于陆内板块作用,在地幔流体的作用下,前寒武基底重熔形成的花岗质岩浆,沿宝鸡～天水深大断裂带与隐伏的武都～天水断裂带的结点发生大规模侵入活动,形成了温泉花岗岩基。随着岩浆的侵入与演化,至陈家大湾斑岩株侵入时,形成富含成矿物质的高压流体相。这些高压流体相,或以液压致裂作用自行开辟通道,或沿有利的断裂构造通道上升,于斑岩株周围形成高含脉率和高渗透率区。同时由于岩浆热所引起的高地热流,造成了地下水与热液长期对流循环及水-岩反应,导致成矿流体沿断裂带两侧围岩尤其是上盘围岩的微细裂隙形成细脉～浸染状钼矿化;由于流体压力的波动,使围岩多次破裂或张合,含矿热液脉动沉淀,形成了相互交错的含矿石英网脉。8、找矿标志与找矿预测:钾硅化、硅化、沸石化、红色泥化、黄铁矿化和孔雀石化等。钾硅化越强,微细网脉越密集发育、且单脉越宽和脉色越深,越有利于成矿;砖红色沸石化发育的蚀变带;红色泥化与岩脉迭加部位有利于成矿;星散浸染状、薄膜状黄铁矿化和孔雀石化等;有利成矿元素组合为Mo、Cu、Ag、As。找矿预测:矿区找矿重点应放在勘探线NEE向的深部;温泉岩体内重点为已发现的42个钼矿化点地质评价,另外要重点研究F₃₂、F₁₆与F₂₀交会之处;区域上钼矿的寻找,应关注毗邻深大断裂带和前寒武纪基底的印支期花岗岩体（脉）出露区。更多还原

【Abstract】 Wenquan Molybdenum Deposit,a large porphyry molybdenum deposit located within the Wushan County of Gansu,was discovered by Bureau of Geology and Exploration for Non-ferrous Metals in 2000. Aiming at the Wenquan Molybdenum Deposit,guilded by the theory of regional metallogeny and prospecting engineering,and starting from the relationship between granitic geochemistry and mineralization,and with the thread of magma-structure-fluid mineralization,this paper makes some studies on the mineralize condition,deposit geology,geochemistry, ore-forming mechanism and laws,etc.and especially sets up the metallogenetic model and predicts metallogenetic prospect.The following are main progress and conclusions:1.Within central orogenic zone（Dabie-Qinling-Qilian-Kunlun）,the previous geological works indicate that not only granitic molybdenum resource,but molybdenum deposits possessed to a certainty scale were only distributed in East Qinling region,which led to the formation of a porphyry molybdenum belt of 52%molybdenum reserves in China and the second largest molybdenum zone in the world,only being second to Climax-Henderson porphyry molybdenum belt in west America.In 2000, however,the discovery of Wenquan molybdenum ore broke the distribution pattern of the Qinling molybdenum belt,west extending this belt by over 400 kilometers,and pointed out the ore-hunting direction in whole central orogenic belt.2.Its regional setting,deposit geology,lithology feature,deposit geochemistry are systematic described in this paper.The studies show that it is a porphyry molybdenum deposit with an average deposit-forming age of 214±7.1Ma,Mesozoic Trias at the Indosinian movement stage.Detailed survey of 15th-32th Lines（0.3km²） in Chenjiadawan finished in June,2007 included the drilling engineering controlled by exploratory density of 100×100～80m and tunnel exploring at 2025m Lever and 2065m Lever,which explored the molybdenum ore reserves of 7805 WT(0.053×10^-2).Furthermore,42 mineral occurrences （mineralized points） in Wenquan rock mass occuring its outside area covering 260km².These show a large-scale molybdenum mine exploration potential of Wuquan Molybdenum Deposit.3.Consisting of medium-grain porphyritic-like monzonitic granite, the intruded rock system of Wenquan granitic batholith include the high greenschist facies volcanic-metasediment of Qinling group, middle-Lower Proterozoic Era,low greenschist facies volcanic-metasediment of Liziyuan group of lower paleozoic,and carbonate, sandstone,shale of Liba-Dacaotan group,middle-upper devonian Era. This batholith is also controlled by the junction location between Baoji-Tianshui-Linxia fracture zone（south side） and Wudu-Tianshui hiddened huge faulting（west side）.The ore-bearing rock body is Chenjiadawan porphyry stock,a complement body of Wenquan batholith, and the emplacement epoch of the former is posterior to the later.The metallogenetic age could be dated 214±7.1Ma,Mesozoic Trias at the Indosinian movement stage.4.At present,there are 34 projects to control ore body,a single body length of 50～650 meters thick 5～24.4m,the top depth of 38.5～516.5m.Mineralization styles include the fracture altered rock, microfissuring quartz vein-net type and disseminated type.Usually ore bodies are produced at the place where the micro-veins densely occur,so the boundary between ore body and host rock is not obvious and is delineated by chemical analysis.The ore is mainly composed of molybdenite and quartz,and the secondary minerals include pyrite, chalcopyrite,blende,scheelite,arsenopyrite,Tetrahedrite,galena,bornite, feldspar and mica and others.Wall-rock alteration include kalium silicification,silicification,zeolitization,red argillization and others except propylitization.5.The mean content of SiO₂ is 71.21%,K₂O is 4.91%,K₂O+Na₂O is 8.22%,K₂O is much greater than Na₂O,Rittmann index（σ） is 2.45,which indicate the ore bearing porphyry belongs to potash-rich cal-alkali rock series.These features are similar to inclusive molybdenum porphyry （Si02 70%～77%、K2O+Na2O 8%～9%,and K₂O is greater than Na2O）, show its potential for good mineralization.Compared with Vickers value, the ore-bearing porphyry is high in Mo、Cu、As、Ag,poor in Bi、Hg、Ba、Au,and the contents of Pb、Zn、Sb、Co、Ni、Cr、V are equal to Vickers’.The mean contents of Mo is up to 45×10^-6 and Cu is up to 142×10^-6,which indicate ore-bearing porphyry magma is the basic substance source for the mineralization.6.Respectively,theΣREE of medium-grain porphyritic-like adamellite,fine-grain porphyry adamellite,dark inclosure and quartz vein are 126×10^-6,148×10^-6,167×10^-6 and 26.8×10^-6,which indicate that the three formers are from the congenetic magma and the latter is the crystallized product of post-secondary hydrothermal fluid.The LREE/HREE value can reach 4.5～5.6,and are 4～5 times higher than those of general granite（1.0～1.2）,which shows obvious LREE enrichment.The（La/Sm）_N value is about 4.6,indicating satisfactory fractionation degree and LREE enrichment,whereas the（Gd/Yb）_N value vary from 1.97 to 2.53,and are obviously higher than those of shell type granite[（Gd/Yb）_N≈1],which indicate poor fractionation degree.The rate of partition curve（La/Yb）_N is 15.13～24.06,rapidly dips rightwardly.The distribution pattern figure of rare earth shows similar variation of curve shape among granite,opaque-color inclosure and quartz vein,which indicates their REE homologue.With growing magmatic differentiation degree,the 5Eu value is decreasing accompanied by more violence europium depletion,theδEu value is 0.66～0.68,negative abnormality and europium depleted type,having features of crust remelting regenerated granite and mantle original granite,which show mantle resource intermingle into it during the period of crust remelting,and which is also the best explanation for basic rock wall（mantle resource） associating with micro-fine grain mafic inclusion intergrowth.The valueδCe is 0.83～0.90,belonging to ceriumdepleted type and weak negative abnormality.7.The dynamics mechanism of the main ore-bearing fault is the intrusion of granitic magma,which results in faulting fractured zone and joint fissure system and finally became the principal host structures.The genetic model of deposit could be supposed as the following:In Indo-Chinese epoch,due to continental plate action and mantle current action,granitic magma intruded along the junction between Baoji-Tianshui fracture zone and Wudu-Tianshui fracture belt,and then became granite batholith.As the evolution and intrusion of the magma,a high pressure fluid phase riching in ore-bearing substance has been formed when the intrusion of Chenjiadawan porphyry stock happened. While it continuely raised and permeated along the available passageways, and led to a high vein-bearing rate and permeability region around the porphyry stock.For long-time convective circulation of groundwater and hydrothermal fluid and water-rock reaction caused by magmatic thermal current,veinlet-disseminated shaped molybdenum mineralization took place in the wall rock along both sides of fracture zone and micro-fissure of the upper wall.On the other hand,due to the varies of fluid pressure and rupture and opening-closing of the host rock time after time,the orebearing hydrothermal fluid sedimentate,and came into being interlaced ore-bearing quartz net-vein.8.The indications of ore include kalium silicification,silicification, zeolitization,red argillization,pyritization and malachitization,etc.If the silicification is more intensive,the net-vein quartz vein is more concentrated and the single vein is more wider and its color is more deep, the metallogenic condition is more favorable.Usually,the ore exist on the zeolitization alteration zone,the superposed location between red argillization and dike,and at some places where isseminated or filmily-shaped pyritization and malachitization are well developed.The favourable metallogenic element combination is composed of Mo、Cu、Ag、As.In minefield,key points for ore prospecting could be the deep parts along the exploratory line in NEE direction,while in the Wenquan rock mass,42 molybdenum mineralization points as well as the intersection of F₃₂、F₁₆ and F₂₀ Could be layed emphases on.Regionally, the Indo-Chinese granitic masses exposured area adjacent to discordogenic fault zone and Precambrian basement could be the ore-hunting prospecting area.更多还原