Typomorphic Characteristics Of Pyrite And Deep Prognosis Of Tiyier Gold Deposit,in Western Junggar,Xinjiang

Tiyier gold deposit is located at the north of Dalabute deep fault in western Junggar,tectonicly it belongs to the Zhayier synclinorium in the Junggar fold belt.The ore-body is hosted in a subvolcanic-andesite porphyrite which belong to the Tailegula Formation,same with Hatu gold deposit,the biggest gold deposit in Xinjiang province.On the basis of the study of previous researches,field geological work and indoor analytic tests have been conducted.Genetic mineralogy and mineral prospecting mineralogy were applied in the systematic study of pyrite-main carrier of gold-in I ore body of Tiyier gold deposit,to discuss the source of ore-forming materials and characteristics of ore-forming fluids.Also deep and peripheral prospecting prediction was undertaken.There are two types of ore rocks:altered rock and quartz veins,mainly the altered rock type.Ore minerals are simple,mainly pyrite,chalcopyrite,arsenopyrite,pyrrhotite,galena,and native gold,and the existence form of gold is intergranular gold and fissure gold in the ore minerals.The texture of the ore is mainly granular and cataclastic,with vein structure and disseminated structure.Ore forming process is divided into four stage,as quartz-potassium feldspar stage???,quartz-pyrite stage???,native gold-quartz-sulfide stage???,quartz-carbonate stage???.Statistics of the particle morphology of 66 pyrite samples from ore-body I show:pyrite is mainly simple cubic and severely fragmented,pentagonal dodecahedron shows up rarely.The pyrite related to mineralization tend to be pale yellow and fine grains of 0.05-1mm particle size,Besides,they are likely to be anhedral.Overlapping with potash feldspathization and silification makes a better gold mineralization.The S/Fe of pyrites varies mainly from 2.00 to 2.12,that are charaterized by being rich in S and poor in Fe.It is revealed that the ore-forming fluid is rich in sulfur.The Co/Ni ratios widely range from 1.8 to 37.2,averaging 2.7,w?Se?of pyrite range from 42.32×10^-66 to 113.52×10^-6,S/Se ratios is 0.5×10^-41.2×10^-4,all show that the formation of pyrite is under dual function of volcanic and hydrothermal function.According to the characteristics of REE and S isotope between pyrite and andesite porphyrite,ore forming material is mainly from mantle or deep magma,ore forming fluid is weak reductant,and successive to the REE pattern of andesite porphyrite.ore-forming temperature calculated by pyroelectric coefficient 100³30?,indicate a medium-low ore-forming temperature.Analysis of Pyroelectricity of pyrite and combination and zoning of trace element shows,It is think the current mine site is located in the upper part of the ore body,ore prospecting potential of line 0 and line 1 under 250m elevation in NW direction is promising.