Geological Characteristics And Metallogenic Regularity Of Dishui Sandstone-type Copper Deposit In Xinjiang

Xinjiang dishui copper deposit is located in the north of Kuqa basin. The ore bed is in the kangcun formation, Neogene. Dishui copper deposit is an old copper mine. It was mined since the Qing dynasty. It is representative among the stratabound sandstone copper deposit in the Xinjiang.In this paper, seam geological characteristics are our main research method. Through describe seam lithologic combination, ore minerals' and gangue minerals' morphological characteristics, structure, mineral assemblages in the polished section and thin section. For some specific minerals, like it can make a contribution to judge the sedimentary environment, we describe them carefully and make a accurate geochemical test. Through this work, we can conclude mineralization regularity of the Dishui sedimentary copper deposit, and analyze the deposit-controlling factors which play an important part in the deposit forming process.Xinjiang dishui copper deposit is a typical continental red beds. The ore bed exists in the reddish-brown, variegated medium-fine or medium-coarse grained sandstone. Part of red beds exist in the upper marlstone. The form of ore beds are layered and lay-like, sometimes it like a streamer. The lithological association which is composed by marlstone-sandstone-mudstone from top to bottom palys a decisive role in the ore deposit's forming process. We collected specimens from some position nearby ore beds in the field and we find a lot of framboidal pyrite in the polished sections. The single framboidal pyrite individual's grain size is less-than 5 micron. We can deduce a conclusion from this that the sedimentary environment is interface of reduction oxidation and is the side of weak reduction environment. And the protosomatic framboidal pyrite have important implications for the ore-forming process. Cuprite is the main deposit mineral, followed by malachite, chrysocolla which distribute in the interface of sandstone and marlstone. There are few sulfide in the seam. Occasionally, we can find some chalcocite, bornite, covellite, in the celadon sandstone and marlstone in the deep mine.Xinjiang dishui mining area is located in the Qiulitage tectonic zone. Fracture structure more development. It is more important influence in the eastern part of mine area. But the faults only dislocate the seam and don't impact on the thickness of the ore bodies and ore grade. So it explains that the faults were formed after the seams' formation period.The deposit forming process of Dishui copper deposit is divided into three stages: primary sedimentary stage, enriched of minerals stage, oxidation-leaching stage. The mineralization mineral originates in provenance of Kuqa basin. The weak reductive environment benefits for the sediment and concentrate of copper. Later, the primordial ore beds become "red beds" after the oxidation-leaching...