Geochemical Characteristics And Genesis Of The Late Paleozoic Intrusive Rocks In The East Segment Of Boluokenu,Xinjiang

The Boluokenu metallogenic belt is one of the important metallogenic belts in the western Tianshan Mountains of Xinjiang.The late Paleozoic intrusive rocks widely developed in the study area are closely related to mineralization.The study on the related properties of intrusive rocks is conducive to the further exploration of ore prospecting.The genesis of Late Paleozoic intrusive rocks widely developed in the area and the tectonic setting of the Late Carboniferous are still controversial.In this paper,the typical intrusive rock Husite intrusion,Dawabulake intrusion and Nailenggele intrusion in the eastern Boluokenu section are studied,like petrography,zircon U-Pb dating,lithogeochemical analysises and Sr-Nd-Hf isotope analysises is carried out.based on this,explore the genesis and tectonic evolution of intrusive rocks.The diagenetic ages of Husite and Dawabulake intrusions are 366-372Ma,366-376 Ma and Nailenggele intrusions are 307-312 Ma,corresponding to the Late Devonian and Late Carboniferous?show calc-alkaline to high K calc-alkaline affinity,i.e,alkalis-rich,high SiO₂ and K₂O contents with high K₂O/Na₂O ratios.the LREE and HREE fractionated obviously,Enrichment of LILE?Rb,K,etc.?,loss of HFSE?Ta,Nb,Ti,P,etc.?.The I_srr values from 0.7044 to 0.7079,I_Ndd values from 0.5121 to 0.5123,and the?_Ndd values from-1.9 to+1.62.The overall performance is characterized by high Sr,low Nd and low?_Nd.The Husite intrusion?_Hf?t?has a large change?-0.9⁹?except for the granodiorite,and the rest of the lithology?_Hf?t?is between 1.3⁵;Dawabulake intrusion?_Hf?t?is between-0.1².1;The?_Hf?t?value of the Nailenggele intrusion is between 4.7 and 7.4,and the overall performance is lower positive?_Hf?t?.The depleted-mantle model ages(T_DM2)is 1162,1182,854 Ma,respectively.Late ancient times and early Neoproterozoic.Sr-Nd-Hf isotope characteristics show that the magma source area has the characteristics of crust-mantle mixing.The Husite and Dawabulake intrusions have higher oxygen fugacity than the Nailenggele intrusions,especially the Husite granodiorite(Ce⁴⁺/Ce³⁺=134),enclave(Ce⁴⁺/Ce³⁺=192)and Dawabulake monzonitic granite(Ce⁴⁺/Ce³⁺=121),have relatively higher oxygen fugacity,and high oxygen fugacity may be beneficial to mineralization.In the Late Devonian,the northern Tianshan oceanic subducted into the Yili plate,and the sediments in the subduction zone melted the mantle wedges to partially melt the mantle peridotite to form basaltic magma,and invaded into the lower crust,making the Middle Proterozoic late neocaps Partial melting occurs to form the Husite and Dawabulake intrusions.The Late Carboniferous,north Tianshan ocean from the subduction and collision to the post-collision extension transition period.The subduction plate fragments are induced to rise from the asthenosphere,and the mantle source magma invades to the crust-mantle boundary,causing partial melting of the Neoproterozoic early lower crust,Formed the Nailenggele intrusion.