Geochemical Characteristics And Genesis Of The Talate Pb-Zn-Fe Deposit In The Southern Altay

Talate Pb-Zn-Fe deposit is located in the volcano-sedimentary Kelan Basin of the South Altay,Xinjiang.It is a middle size Pb-Zn-Fe polymetallic deposit of Aletai City,and the study of the geochemical characteristics and genesis to Talate Pb-Zn-Fe deposit means a lot to further prospecting.This thesis focused on the study of the Talate Pb-ZnFe deposit,and carried out detailed geochemical characteristics investigation,mineralogy,geochronology,fluid inclusions and stable isotopes to disscuss the ages of intrusion and mineralization,nature and source of ore fluids,source of ore-forming material.Based on the comparison with other deposits in the same area,the metallogenic regularity was summarized.The host rocks of Talate Pb-Zn-Fe deposit is Upper Silurian-Lower Devonian Kangbutiebao Formation.The ore bodies are mainly layer and layer-like,but it is common that the appearance of Pb-Zn ore bodies is vein and lenticular with relating skarnization and silicfication.The main minerals include sphalerite,galena,magnetite,pyrite and others.Based on field geological survey and the study on microscope,the ore-forming processes can be divided into exhalative sedimentary and hydrothermal alteration periods.The former ore-body is layer and layer-like,the latter is vein.Mineral petrography and chemistry indicate that the main minerals of Talate PbZn-Fe deposit,such as sphalerite,galena,and pyrite are formed in middle-high temperature condition,and the ore-forming liquid is full of S,but pyrrhotite is formed in low temperature condition.The LA-ICP-MS data of magnetite and sphalerite shows that ore-forming material of vein ore-body could be magma.The age of the host formation is 407?413Ma,the Re-Os weighted mean ages of vein ore molybdenite are 250.8±3.1Ma,and the Rb-Sr isochron age of pyrite and sphalerite is 246.2±3.7Ma,which means exhalative sedimentary was happed in Late Silurian-Early Devonian,and the late magmatic hydrothermal alteration might be earlier than Late Permian,furthermore in Late Permian,Talate Pb-Zn-Fe underwent some hydrothermal alteration.Based on the study of fluid inclusion,the source of vein ore fluids of Talate PbZn-Fe deposit is middle temperature and moderate-high salinities.The study of H-O isotope and He-Ar isotope indicate that the source of vein ore fluids might mainly be from crust,but could be participated by mantle.On the other hand,He-Ar isotope data of layer ore suggests that the source of layer ore fluids might partly be from crust.The data of Re and Sr indicates that source of vein ore-forming material may be related with mantle,and the same conclusion can be summarized by the data of S isotope,by the way,source of layer ore-forming material may be the mixture of mantle S and biological effects.