Chronological,Petrological And Geochemical Characteristics Of Intrusive Bodies In Tiyier Gold Deposit In Western Junggar,Xinjiang

Tiyier gold deposit is a newly discovered deposit which is located in West Juggar,Xinjiang Province.The ore body is hosted in a syenite porphyry(T-?),and the intrusive body is wholly mineralized.In this paper,the study aims at the two intrusive bodies in Tiyier gold deposit,the intrusive bodies are syenite-porphyry numbered as T-?,T-?.On the basis of the research on the field geological survey and indoor chip study,in order to explore the space-time distribution characteristics,the source material of magma and tectonic environment of the intrusive bodies,we use LA-ICP-MS zircon U-Pb dating analysis,whole rock analysis,to determinae the K-rich intrusive rock formation ages,petrochemistry,rare earth and trace element geochemistry.Result shows,T-1 intrusive body was formed at 355.1±3.4Ma,T-2 intrusive body was formed at 369±3.2Ma,the two intrusive body have similar age,which fall into late Devonian to Early Carboniferous.Those rocks with elevated contents of total alkali and potassium belong to intermediate rocks,on the basis of major elements study and microscopic observation,the rock in both intrusive body was determined to be syenite-porphyry.Rock series study shows,the rock belongs to Shoshonite series.The rock belongs to A-type granite.Rocks are characterized with high total REE concentrations,high LREE,obviously fractionation between LREE and HREE.Rare earth and trace element distribution curve of different rocks parallel to each other,reflected their homology.T-1 rock mass has weak negative Eu anomaly,while T-2 rock mass possess a weak positive Eu anomaly.This indicate the discrepancy during their evolution.The rocks show enrichment of LILE,LREE and Sr,P,Ti negative anomaly.The low Mg# show a high degree of magmatic differentiation evolution.The result of La/Sm-La diagram and Haker diagram in combination with microscope observation shows rock forming magma underwent crystallization differentiation.Trace element study shows,rock forming magma originates from enriched mantle,crust material may mixed in during the magmatic evolution.On the basis of regional geology background,rock-forming age and rock geochemical,intrusive bodies in tiyier gold deposit may form under the circumstance of island arc-back arc basin which was created by the Junggar plate westward subduction.