Research On Geological Features Of Yinchanggou-Qiluogou Lead-Zinc Ore Deposit, Ningnan County, Sichuan Province

The Yinchanggou-Qiluogou Lead-Zinc Deposits in Ningnan County, Sichuan Province is located in southwestern margin of the Yangtze platform, it belongs to sub-metallogenic area of the Upper Yangtze districts in Metallogenic Province of the Yangtze Para-platform, and it is also an important part of the Sichuan-Yunnan-Guizhou lead-zinc polymetal metallogenic belt.Based on the results of previous studies, field investigation and laboratory analysis, this paper analyzed in detail geological features of ore deposit and ore-controlling factors of the Yinchanggou-Qiluogou Lead-Zinc Deposits, and systematically studied ore geochemistry characteristics, then deeply discussed genesis of the deposit. After study above, the conclusions follow as:(1)All orebodys of the Yinchanggou-Qiluogou Lead-Zinc Deposits occur in the dolomite with siliceous bands, the upper Dengying Formation of Sinian System, and show the metallogenetic specialization of the lithology and lithofacies.(2) In ore-controlling structure, the orebody are controlled by the interlayer fracture zone and fault structure. The interlayer fractured orebody occur in layered form, veined orebody controlled by fracture of trend to NNW direction, tend of E direction, and occur in veinlets, net vein, lenticular.(3) Ore is characterized by cementation texture, bioerosion texture, interstitial texture, poikilitic texture, replacement lattice texture, replacement remnant texture, massive structure, veinlet structure, desseminated structure and banded structure. There mainly are silicification, carbonation (dolomization and calcilization), gasification and fluoritization, of which silicification is closely related to mineralization.(4) By means of research on the minerogenetic, intercalating relationship, cementing relationship and brecciated structure with microscope, the mineralization stage of the deposit can be divided in syngenetichy stage, drothermal stage and supergene stage. The deposit is charactered as multi-stages of which the main metallogenic stage is drothermal mineralization stage.(5) Based on the study of trace elements of the ore and surrounding rock of the deposit, the author thinks that the formation of the lead-zinc deposit suffered strong transformation, the formation of the deposit have experienced the complex evolution.(6) Based on analysis on stable isotope of the deposit,lead in the metallogenic deposit come from upper crust,a small amount of lead from the deep crust. Main mineralization stage is the later drothermal mineralization stage. Sulfur come mainly from submarine evaporation sulfate; the water in handling medium came mainly from a mixture of waters which consist of the Sinian stratigraphic of sedimentary water and metamorphic rock of the overlying basal formation. Carbon came mainly from carbonate rocks (the surrounding rock).(7) We can inferred the two ore deposits are not result of the same mineralization in Yinchanggou-Qiluogou Lead-Zinc area.(8) Studying on fluid inclusion, that the ore-forming fluid possess middle temperature, middle salinity, middle medium pressure and low density in characteristics is indicated.(9) Whether the geotectonic background or mineralization features, that the deposit type is the stratabound deposits controlled by structure and formature is shown.