Genetic Type and Prospecting Criteria of Bieluwutu Copper-sulfur Polymetallic Mine in Inner Mongolia

Bieluwutu copper-sulfur polymetallic mine is a larger deposit in central Inner Mongolia. The geochemical analysis of main minerals indicate that the iron pyrite has the characteristics of the magmatic hydrothermal-type iron pyrite such as low S/Fe ratio (from 1.795 to 2.002) and high Co/Ni ratio(more than 1). Orpiment iron pyrite, lead zinc ore and sphalerite all present the features of the mid-high temperature genetic minerals. Combining the structure characteristics of the ore, formation order of minerals, alteration of surrounding rocks and formation temperature of the deposit, the authors believe that the genetic type of the studying deposit is vein deposit of hydrothermal filling metasomatic type after the magma stage. The δ³⁴S‰ value of pyrite, orpiment iron pyrite and arsenopyrite is within a narrow range between 0.2‰ and 1‰, approximate to the sulfur content of meteorites. It is indicated that the metallogenic material is possibly related to the neutral-basic intrusive rocks in late Variscan. The direct prospecting criterion is gossan, which is the product of metal sulfide weathering and leaching. Moreover, the late Variscan intrusive rocks, NEE-WE fractures and obvious hydrothermal alteration such as silication, chloritization and talcose are also important prospecting criteria.