The Study On Mineralization Of The Basitielieke W Polymetallic Deposits In The Altay,Xinjiang

The medium-tonnage Basitielieke deposit is the first W polymetallic deposit discovered in Altay,Xinjiang.The discovery of the Basitielieke deposit is of great significance.It is hosted in the meta-volcano-sedimentary rocks of the Upper Silurian-Lower Devonian Kangbutiebao Formation which is located at the external contact zone of biotite adamellite.Orebodies occur as stratiform-like and lenticular in skarn.Based on the full field investigation,this paper has obtained the following results through the study of the geological characteristics,skarn minerals and metal minerals,fluid inclusions,geochemistry,metallogenic epoch and mineralization mechanism of the Basitielieke W polymetallic deposits:(1)The mineralization experienced skarn period and supergene oxidation period and the skarn period is composed of the early skarn stage,the degenerate alteration stage,and the quartz-sulfide stage.(2)The mineral electron probe analysis show that the terminal component of the pyroxene is mainly composed of diopside and few hedenbergite;garnet is mainly composed of grossularite;biotite is mainly composed of ferromicas;The type of feldspar is orthoclase;The characteristic of epidote is have more Ca,Al and less Fe;The type of sphalerite is marmatite and other metallic minerals are pyrrhotite,chalcopyrite,tin,arsenopyrite,bismuth and argentite.(3)Hydrogen and Oxygen isotopes imply that the ore-forming fluids of the early skarn stage is mainly magmatic fluids,and the quartz-sulfide stage is mainly magmatic fluids with a minor part of meteoric water;the Sulphur isotopes show that the sulphur of ore-forming fluid is mainly from mantle,and it is related to the hydrothermal action after the granitic magma around the mining area.(4)The pegmatite zircon U-Pb dating results limit the mineralization earlier than 275Ma;the Re-Os age of molybdenum ore determines the mineralization of Cu-Zn(associated Au)at 284 Ma,and the formation of scheelite is earlier than 284 Ma.Basitielieke W polymetallic deposit is early Permian mineralization.(5)The ore-forming mechanism of the deposit is a series of skarn formation from the Early Permian mining area to the Kesiergui area biotite adamellite magma intrusion into the Late Silurian-Early Devonian Kangbulibao Formation metamorphic volcanic sedimentary rock series.The tungsten ore are formed in the stage of degraded alteration,copper-zinc ore is formed in the quartz sulfide stage,and the deposit is skarn type W polymetallic deposit.