A Comparative Research On The Tectonic And Sedimentary Background In Late Paleozoic In Beishan And Yin’Gen-eji’naqi Area

Based on structural geology, petrology, sedimentology, geochemistry, trace elementgeochemistry, isotope geochemistryand other disciplines，by mean of collecting and analyzingprevious information about the research area, combining with outcrop geological investigation,laboratory testing and other methods of analysis,the development features of the strata,magmatic rocks, tectonic in Late Paleozoic are studied.The Devonian is a transition period of tectonic evolution, the Middle Devonian is the endof the plate tectonic evolution stage,In the Late Devonian the research area is in the stage ofcontinental evolution; By a comprehensive analysis of sedimentary features andcharacteristics of magmatic rocks founding that the Beishan and the Yin’Gen-Eji’naqi areaCarboniferous-Permian are overall in the post-orogenic extensional tectonic setting, and aseries of rift basin are formed，but they are not synchronous in the tectonic evolution of theprocess, by analysising the strata deposit time, magmatic intrusion time and the regionophiolite/melange formation time,it displayed that Beishan area in the continental extendedand closed earlier than Yin’Gen-Eji’naqi area, And for the first time a detailed Late Paleozoictectonic evolution chart about Beishan and Yin’Gen-Eji’naqi is drawed.The Carboniferous granite in the Beishan area is mainly I-type and the granite magma isfrom the crust, the Permian granite is mainly A2-type, the magma is from the mixed crust-mantle,but the ratio of magma from the crust is larger than from the mantle. But both theCarboniferous and the Permian granite in the Yin’Gen-Eji’naqi area are mainly I-type, and themagma are both from the mixed crust-mantle. In addition, the REE patterns diagrams havesimilar distribution patterns,it implys that they are probably both the result of the samecognate magma evolution, The difference between them is that the Carboniferous samplesnegative Eu anomaly weaker than Permian samples. It indicates that Permian rock samplesplagioclase fractional crystallization stronger than the Carboniferous’.The granite in Beishanarea have the characteristic that carboniferous is mainly calc-alkaline series and the rock classtranforms from calc-alkaline to alkaline primarily in Permian; But in Yin’Gen-Eji’naqi area,the granite is mainly calc-alkaline series in Carboniferous and Permian,it shows that thecrustal maturity of Beishan area is bigger than Yin’Gen-Eji’naqi in Permian. Recent research shows that Hongshishan ocean was a type of limited ocean like as theRed Sea in the late Paleozoic, which does not have the characteristics of dividing land mass,Therefore, it is inappropriate regard the time of Hongshishan ocean closing as Paleoasianclosing time is inappropriate Paleoasian closing time should be earlier than the LateDevonian.In addition, through in-depth research of the "En’ge’erwusu ophiolite belt" in recentyears, it is considered to be a melange belt, which does not have the nature of suture zone inthe Late Paleozoic, so the suture zone between the north China plate and Tarim plate does notexist in Yin’Gen-Eji’naqi area.