| The Uragen Zn–Pb deposit occurred in Mesozoic-Cenozoic basins in Kashi sag, Xinjiang,whose reserves are second only to Yunnan jingding and which is the second lagerest clastic sedimentary-hosted lead-zinc deposit,Study on mineralization of the deposit is a commodity in the spotlight.The large scale,superior minerogenetic conditions and remarkable economic meaning have attracted many researchers to explore it,putting forward a lot of different causes of deposit.It was identified as a small hydrothermal deposit initially,then propsed sedimentation reform genesis,some researchers compared it with Yunnan Jingding deposit,thought it SEDEX or MVT. Resently,it was known as SST,ore forming fluid is oilfield brine. Since the deposit has been discovered,few scholars have put-in depth study on the structure and texture of ores,so the text selects the structure and texture of ores as the research object,.Using the polarizatiaon microscope,electron probe and scanning electron microscope,structure of two kinds of ore and texture of different metal minerals are summarized in detail, and the text tries to discuss its gellogical significance.The main results achieve and understanding are as follows:We found a large number of oyster fossils in Grey green mudstone of Eocene series Wulagen Formation,after identification of fossils,we hold the opinion that the fossils are not native,which are took here from intertidal zone under the power of tides.The host rocks can be classified into two kinds according to the lithology of ore-host strata: sandstone hosted ore and carbonate hosted ore. Type of detrital minerals of sandstone are maily quartz,feldspar and ithoclast,cement is maily calcite.Carbonate rocks are mainly composed of calcite,and a little dolomite. The main primary metal minerals are mainly composed of sphalerite,galena,pyrite and marcasite.Ore strcture maily includes disseminated、taxitic、veined、banded and brecciated structures and so on. They are result of hydrothermal filling metasomatic rocks along pore,crack,parallel bedding,or fracture zone. The main texture of ore is melting corrosion,metasomatic relict texture, metasomatic pseudomorph texture,cementation texture and so on,they are also the result of metal mineral metasomatic detrital grains. when the metasonmatism is weak,the edge of the detrital grains are corroded,and formed melting corrosion texture; Further development of metasonmatism,most of the detrital grains are corroded,and detrital grains are less than metasome in number,then metasomatic relict texture formed;when the metasonmatism is complete, the detrital grains are all corroded,and formed metasomatic pseudomorph texture,if the cement are all corroded,then cementation texture formded. The sequence of the formation of mineral is: framboid pyrite-granular pyrite-marcasite-galena-sphalerite.The ore fabric Indicates that the deposit is epigenetic,and which is the result of filling metasonmasis of ore-bearing hydrothermal. Part texture of ore indicates that the ore-bearing hydrothermal is rich in organic matter and bacteria play an important role in the course of mineralization.Based on the analysis of the previous studies,the deposit belongs to sandstone type and which is related to regional fluid. |
PDF Full Text Request