Petrogenesis And Tectonic Implications Of The Late Paleozoic Intermediate-mafic Intrusive Rocks In Kawabulak Area,Central Tianshan

In this article,through field geological survey and indoor test analysis and research,to the slip braque tianshan mountain intermediate-mafic intrusive rocks in the detailed petrographic,chronology,zircon Hf isotopic elements and whole rock geochemical analysis,discusses its formation age and rock formation,and in combination with regional geological data,the southern margin of tianshan mountains in the late Paleozoic tectonic setting is discussed,and provide qualified south tianshan ocean tectonic evolution process constraints.The main achievements are as follows:1.The neutral rock in the Kawabulak area of Central Tianshan is a long strip spreading to the east and west,which intrudes into the jixian system of jixian in zhongyuan,which is a quartz diorite.The base rock is near the east and west to the spreading cloth,and it intrudes into the rock group of the xingxingxia and the jixian of zhongyuan ancient boundary,and the lithology has plagioclase and olivine gabbro.2.Zircons from representative samples of LA-ICP-MS U-Pb isotope analysis results show that the quartz diorite formed in 412.2±3.2Ma,anorthosite formed in297.1±3.1Ma,that Intermediate-Mafic Intrusive Rocks in Kawabulak Area is formed in different period times the product of magmatic activity,respectively,on behalf of the late Paleozoic early and late magmatic activity.3.The SiO₂ content of quartz diorite is 58.63%⁶3.66%,which belongs to the neutral rock class.Al₂O₃ content was 14.88%¹6.02%;The low magnesium index（Mg^#=22.95³2.33）and TiO₂ content（0.88%¹.50%）indicated that they had experienced the crystallization differentiation of mafic minerals and indicated that they were not crystallized by primitive basaltic magma.The SiO₂ content of the plagioclase and olivine gabbro is 46.22%⁴9.33%,which belongs to the base rock type.Al₂O₃ content was 13.18%²6.55%;High magnesium index（Mg^#=64.06⁷5.05）and low TiO₂ content（0.11%¹.07%）.The Na₂O/K₂O of intermediate-mafic intrusive rocks is greater than 1,showing the characteristics of low potassium.It belongs to the subalkaline series.4.intermediate-mafic intrusive rocks in the enrichment of light rare earth elements,rare earth distribution curve is smooth,the whole leaning to the right,quartz diorite Eu negative anomaly is not obvious,anorthosite and olive gabbro Eu is abnormal;There is no obvious Ceabnormality,and the high field strength elements show different degrees of losses.The characteristics of the mixed source region of the shell and mantle were demonstrated by the characteristics of the high concentration of the quartz diorite in the concentration of theε_Hf（t）（+0.3⁺15.4）and the range of variation.It is indicated that the influence of the magma mantle source is not strong.5.Quartz diorite formed in the early devonian south tianshan ocean north to dive beneath the tianshan mountain massif in the active continental margin environment,overlying mantle wedge through the subduction zone fluid metasomatism occurs molten basaltic magma formation,the bottom of the basaltic magma invasion base under the earth’s crust,lower crust formation of granitic melt partial melting occurs,the combination form of andesitic mass assault on slurry consolidation form quartz diorite rock diagenesis.Anorthosite and olive gabbro formed in extensional environment after the collision of the late carboniferous to the board,soft flow enclosure mantle upwelling,and partial melting in the corresponding pressure relief,repass plagioclase,olivine,and separation of orthopyroxene crystal/heap crystal effect has formed length and olive gabbro rock mass.6.In the southern margin of tianshan mountain in 412Ma in an active continental margin tectonic environment,at this stage in south tianshan ocean north to dive in tianshan mountain massif,and south tianshan ocean has completely died in 297Ma,in the southern margin of tianshan mountains in the intraplate extension environment.