Study On Ore Characteristic Of Garjoan Copper-gold Deposit, Gejue County, Tibet

Garjoan copper-gold deposit locates in the intersection of the Shiquanhe Late-Yanshan Junction Zone and Gangdese-Nyainqentanglha plate which belongs to the western section of the Bangong-Nujiang suture zone, Tibet. It is the first medium-sized copper-gold deposit which obtains detailed survey. The mainly orebody occurres in contacted belt between intermediate-acidic intrusive rocks and carbonatite,which is approximately 900-meter along NWW in strike and far greater than 400-metre along NNE in trend. The ore minerals are dominated by Cu-Au with main accompaniment element Ag. Wallrock alteration is developed and mainly characterized by skarnization, carbonatization, silication, chloritization, epidotization and sericitize which related with metallogenesis mainly including skarnization, carbonatization, silication, chloritization and epidotization.On basis of systematic drillhole geologic record and detailed petrology-mineral study ,This paper described ore types and characteristics according to analyzing specific rock ore appraisal and testing ,and by means of a scanning electron microscope and an energy spectrum of 78 polished-thin-section. Ore texture mainly are metasomatic texture, crystallzation texture and unmixing of solidsolution texture. Structure of ores are dominated by disseminate, vein and veinlet structure. More than 57 metallicmineral and 16 nonmetallic minerals has been appraisaled in which approximately 20 gold and silver mineral were found, as native gold, electrum, silver-bearing native gold, kustelite, petzite, cuprian gold, auricupride, native silver, argentite, stromeyerite, iodyrite, cerargyrite and hessite,etc.The occurrence of the essential element in area is ascertained by means of optical microscope and SEM analysis methods. Occurrence of gold in the ore is simple which makes extraction easily in mineral processing. The result shows that the gold is mostly locates in carbonate and iron mineral with different forms such as limonite, iron claylike minerals, etc. The main occurrence states of Au are embedded-gold ,fissure-filled gold and the microfissure Au. The gold mainly includes native gold, electrum, auricupride and cuprian gold and so on. The main copper minerals are chalcopyrite and bornit which are dominantly veinlet-disseminated and sparse- disseminated in gangue mineral. Silver minerals mainly include native silver and Ag-sulfide which chiefly exist in fracture, druse and pore of quartz, carbonate and chalcopyrite, parting with enclave.