西藏甲玛铜多金属矿床铜山矿体为manto型矿体?

摘要

Manto-type mineralization refers to replacement along strata and is characterized by stratabound nature, obvious structural control, high grade, and sulfide-rich ore. The Jiama deposit, a superlarge porphyry-skarn deposit, is located in the east of Gangdise metallogenic belt, Tibet. It has been the important achievement of thecombination of nonprofit exploration with commercial prospecting. Tongshan (south pit) orebody is a prospectingbreakthrough after exposing Jiama concealed porphyry orebody. The proven resources of the Tongshan orebodyreach >0.7 Mt Cu, 0.02 Mt Mo, 1.2 Mt Pb+Zn, 20 t Au, and 2000 t Ag. Tongshan orebody is 1km away from theporphyry center. Tongshan orebody is controlled by Tongshan gliding nappe structure, in which there are manysecondary folds and fractures that provided space for migration and precipitation of hydrothermal fluid. Tongshanorebody, hosted in the Linbuzong Formation hornfels, Duodigou Formation marbles, and the interlayerdetachment zone between the Linbuzong Formation hornfels and the Duodigou Formation marbles, exhibitslenticular, veined, cystic, and podiform forms. Tongshan orebody is sulfide-rich and includes chalcopyrite,sphalerite, galena, bornite, magnetic pyrite, pyrite, and molybdenite. The average grade of Cu is 0.99%, and thatof Pb+Zn is 2.88%. These geological findings led the authors to believe that Tongshan orebody are distalmanto-type ore of the porphyry copper system, as evidenced by field geological investigation and comparisonwith other manto-type deposits. This is for the first time a deposit of this significant type was found and verifiedin Gangdise belt, which is of great guiding significance in search for peripheral manto-type ore deposits in otherporphyries and skarn deposits in the Gangdise metallogenic belt. It has high economic significance, and thesouthern open pit which can process forty thousand tons per day has been built.%manto型矿化是指"沿层交代"并受地层控制,构造控矿,品位高,富含硫化物矿石.甲玛铜多金属矿床位于西藏冈底斯成矿带东段,在公益性与商业性勘查结合下,取得重大找矿突破的世界级超大型斑岩-矽卡岩型铜多金属矿床.铜山(南坑)矿体是继揭露甲玛深部斑岩矿体之后的又一找矿重大突破.铜山矿体规模达到大型,铜金属量70多万吨,钼金属量2万吨,铅+锌金属量120多万吨,伴生金金属量20多吨,伴生银金属量2000多吨.铜山矿体距离斑岩体中心1 km,受铜山滑覆构造控制,滑覆体内部次级褶皱、裂隙发育,为热液流体运移、沉淀提供了良好的空间;赋存于林布宗组角岩、林布宗组角岩和多底沟组大理岩层间及多底沟组大理岩中,呈透镜体、脉状、囊状、豆荚状;富含硫化物,主要为黄铜矿、闪锌矿、方铅矿、斑铜矿、磁黄铁矿、黄铁矿、辉钼矿等;品位较高,铜平均品位0.99%,铅+锌平均品位2.88%.通过野外地质调查,并与世界上其他manto型矿体对比,甲玛铜山矿体属于斑岩成矿系统远端的manto型富矿体.甲玛manto型矿体的发现和确定在西藏冈底斯成矿带上尚属首例,对该成矿带其他斑岩、矽卡岩矿床寻找外围manto型富矿体具有极其重要的指导意义,其经济意义也十分巨大,目前已经建成日处理4万吨的露天采场.