Geological And Geochemical Characteristics Of The Bayinbulake Granite Porphyry In West Junggar And Its Indicative Significance

The Bayinbulak rock mass is located in the Kazakhstan-Junggar plate,the Junggar-Balkash microplate,and the southeastern part of the Semystein metallogenic belt in the central West Junggar region.Its formation is strictly Chagan-Tolegai-Bayinbulak.Fracture control.In this paper,petrographic porphyries,geochemistry,geochronology and isotopic geochemistry of the granite porphyry in the Bayinbulak rock mass have been carried out.According to the zircon U-Pb geochronology work,the age of granite porphyry was determined.Combining geochemical and isotopic geochemical results,the origin and structural background of the rock mass were deduced.At the same time,some metal deposits in the West Junggar region were collected.The metal ore deposits in the same or similar era as Bayanbulak Rock were selected for comparison,and the similarities and differences between the two were briefly analyzed.In terms of petrographic characteristics,the Bayinbulak rock has a patchy structure and massive structure.The speckles are mainly quartz,potassium feldspar,and a small amount of muscovite.Some quartz has a bay-like structure,and a few quartz phenocrysts have a ring edge,and a few of the K-feldspar Krishites have developed.The main minerals are:zircon,apatite,rutile,titanium iron oxide and so on.Geochemical analysis shows that the Bayinbulak granite porphyry is characterized by low water content,high silicon content,and high alkali content,especially potassium and magnesium.Th,U,Zr,and Hf are enriched,K,Sr,and P.Ti showed a loss,and the total amount of rare earth elements was high(REE:236.8×10^-6327.6×10^-6),and light and heavy rare earth fractionation was significant?LREE/HREE:6.48⁹.99;LaN/YbN:5.96⁹.07?.The Eu negative anomaly,10000Ga/Al between 2.59³.14,has a typical A2 type granite characteristics.The zircon U-Pb geochronology of Bayanbulake granite porphyry was studied by LA-ICP-MS method.The results showed that the age of formation of Bayinbulake granite porphyry was 393.7±1.7Ma?MSWD=1.3,n=20?belongs to the early Devonian product.According to the results of isotope tests,the I_Srr of Bayanbulak granite porphyry is between0.699⁰.706,?_Nd?t?is between 4.3⁶.1,and the Nd two-stage model age is between591⁷88Ma.The?_Hf?t?ranged from 3.98⁹.35,and the Hf two-stage age ranged from790¹130Ma,with an average age of 910Ma.The diagenetic material may have come from the loss of mantle and involved the ancient crustal material of the Precambrian period.The data from the deputy mineral electron probes show that the zircons in Bayanbulak granite porphyry can be divided into high uranium zircon and low uranium zircon.Among them,the UO₂ content of high uranium zircon can reach up to 0.36%,which is an important uranium-bearing mineral in Bayanbulak granite porphyry.Titanium-iron oxides can be classified into two types:high-titanium-iron-depleted and high-iron-titanium-poor.The high-iron-titanium-titanium-iron oxides have high uranium content,and the UO₂ content can reach 0.07%,considering both Ti and Fe.As the main element,high-iron type titanium iron oxide may be another important uranium-bearing mineral.After comparing with Yangzhuang rock body and regional ore-bearing porphyry,it is believed that the Bayinbulake area has more prospective uranium prospects.