The Genesis Study Of Zhaxikang Lead Zinc Antimony Silver Deposit, North Himalayan

Zhaxikang lead-zinc-antimony-silver deposit is located in the North Wing of southeast Yangzhuoyong-Nariyong double syncline of North Himalayan gold-antimony polymetallic deposit. At present there are 9 ore bodies in the ore area, in whichⅥ,Ⅴ,Ⅵorebodies are the main ore mining, the total amount of resources (332+333+3341) Pb+Zn+Sb is greater than 1 million tons; Ag is greater than 1,500 tons, and it is the largest and the only multi-metal deposit in the North Himalayan metallogenic belt.The main ore-bearing stara of the zhaxikang ore area is the fourth section lithologic of the Lower Jurassic'RiDang group, which lithology constitution is gray and black carbonaceous slate,interling brown and yellow calcareous sandstone and a small amount of discontinuous distribution of limestone, diabaseand tuff pulse. Ore bodies mainly occurred in high angle tenso-shear faults in the SN direction, a few occurred in the NNE trending faults. They are strictly controlled by faults. The upper part of the ore bodies often have branch and compound phenomena, the lower part is relatively continuous.The types of ore are variety, the main structure of the ore are lump,banded, vein-stockwork, brecciated, ring, druse-like, radial, finger-like and so on. Its main texture are shape-half shape granular texture, granular texture, skeletal crystal texture, interstitial texture interspersed texture, account texture, containing and total edge texture.The component of the ore are complicated.It has a certain horizontal and vertical zonation. ore minerals are mainly sphalerite, galena, zinkenite, jamesonite, stibnite, a small amount of chalcopyrite, wheels ore,silver tetrahedrite, lead silver antimony sulfur, antimony ore and other parties, occasionally there are azurite, malachite; gangue minerals are mainly pyrite, siderite, quartz and calcite. The oxide ore mineral is composed of limonite, calamine, auglesite, valentinite and so on.According to the relationship of replacement and filling between ore intersection and mineral, the ore-forming stage was divided into chalcopyrite-pyrite-galena-sphalerite stage, siderite-fine pyrite-galena sphalerite vein stage, quartz-arsenopyrite-pyritestage, quartz-pyrite-bourninote -jamesonite-stibnite-sphalerite-galena (in fine) stage, galena-pyrite stage (coarse vein) and the hot springs silicon stage(wrapping breccia ore).Fluid inclusion studies show that the ore-forming fluids is in the medium temperature (199～328℃)-the medium -low salinity (0.7～12.5%)-the medium -low density (0.95～0.65g/cm3) category. The fluid composition changes from early stage to late stage as SO42--Cl--Na+-Mg2+-K+ type→SO42--Cl--Na+ type→SO42--Na+ type.δDV-SMOW values of water in fluid inclusions of quartz extend from -127‰～135‰,δ18OH2O to -13.7‰～12.4‰, swerve to the distribution of geothermal water in Tibet, and a large number of precipitation join in late stage. He-Ar isotopes show that the ore-forming fluid is mixed with saturated crustal fluids and meteoric water, mixing of mantle fluid composition is not apparent.The 834S value of ore minerals such as pyrite, sphalerite, galena, jamesonite, stibnite changes in the 4.5‰～12.0‰, the majority concentrated in a range from 8‰to 11‰, enriched in sulfur and in a narrow range, indicating that they have the same sulfur source, mainly from the marine sulfur reduction of the rock formation. The range of the ratio of 206Pb/204Pb,207Pb/204Pb, 208Pb/204Pb is 18.474～19.637,15.649～15.774 and 39.660～40.010, and they are all in a straight line ,has the characteristics of radioactive and anomalous lead, falling near the line of earth's crust lead. Late Triassic-Early Jurassic in the abundance of ore-forming elements and ore mining in the mineral-stratum-diabase trace element characteristics of rare earth comparison that Late Triassic-Early Jurassic turbidity, or exhalation of a carbon-enriched silicon mudstone strata forming elements for providing a rich source to the forming the material.The metallogenic age of Zhaxikang deposit is 18.3～23.3Ma, which is close to the metallogenic age of North Himalayan (13.3～24.2Ma), indicating that the mineralization and the Miocene collision tectonic of India-Europe and Asia plate after between movement related to the extension change. The early stages of the North Himalayan region mainly anti-lower crust north to south, the direction of flow and the crustal shortening, the formation of EW to the extension of the southern Tibet detachment system (STDS), crustal magma generated by partial melting along the southern Tibet detachment system and interlayer fracture zone penetrated, was in the region constitutes the EW to the distribution of metamorphic core complex belt; the late stages of major changes in the stress field, mainly EW to extend, forming a series of SN to the normal fault systems and rift system. And post-collision tectonic compression to extension conversion, while large-scale occurrence of gold-antimony, lead, zinc and silver mineralization, and because the structural properties of different causes or determines the ore-controlling structures and mineralization differences between sex. Charles rapp as gold, philosophy of ancient gold-antimony deposit, madzala antimony deposit, salad posts by antimony and other major southern Tibet detachment system and associated EW fracture zone to the layer control, and Zhaxikang lead-zinc-antimony-silver,Cheqiongzhuobu antimony, Rangla antimony, etc. are pulling soil occurs in SN Zhang to the high angle shear faults. Ore-controlling structure in order from north to south from the EW fracture zone between the layers into a nearly SN mainly high angle faults to the main. In addition, the isotopic composition of Zhaxikang lead- zinc- antimony-silver deposits have obvious differences with known gold (antimony) deposit, but also that the specific characteristics of its mineralization. Fluid of the Zhaxikang deposit mainly underground water, forming materials mainly from the upper crust formation, while the gold (antimony) deposit isotope composition of its ore more display involvement of magmatic fluids and substances.The metallogening of Zhaxikang antimony-silver-lead-zinc deposits was a series of SN direction of high-angle fault zone which were formed in the Indian plate colliding to Eurasian plate in Miocene post-collisional transition environment from intra-continental orogeny to extension slip in North Himalayan belt, and it promoted partial melting of crust which causing local heat flux increase sharply and geothermal gradient anomalies increase, driven groundwater convection cycle, extracted metallogenic elements from Late Triassic-Early Cretaceous turbidite or black carbon and silicon gray mudstone strata, formed by replacement and filling along along the SN fault zone, which belongs to Sedimentary-structural-geothermal water multi-stage replacement and hydrothermal vein deposits.