The Petrology Characteristics And Petrogenesis Of Ultramafic-mafic Rocks In The Western Part Of Eastern Kunlun Of Yanbishan

1.It is well-known that ultramafic rocks and mafic rocks are basically derived from the upper mantle and are the most direct target for the study of mantle materials.It has been found that ultramafic rocks and mafic rocks are mostly distributed in plate structural boundaries.This is to explore the plate.The tectonic movement and the subduction and subducted evolution of the plate have very important significance.The ultra-mafic rocks and mafic rocks of Yanbishan are controversial in terms of rock types and petrogenesis.Therefore,this paper passes the petrology and mineralogy of the Yanbishan ultramafic rocks and mafic rocks.Mineral chemistry,chronology,and petrochemistry were analyzed to determine the type of rock,and the petrogenesis of the Yanbishan ultramafic rocks and mafic rocks and the structural background of the formation were discussed.After detailed research,the following main understandings and results have been obtained:2.The Yanbishan ultramafic rocks are mainly composed of serpentinite pyroxene peridotite and serpentinite olivine pyroxenite,and the mafic rocks are hornblende chervizite and pyroxenite gabbro gabbro.In the serpentinized pyroxenite peridotite,the olivine with an Fo value around 87 is olivine,and the fortite with a Fo value above90 is forsterite;the composition of orthopyroxene in the pyroxene peridotite is Wo?0.12⁵.67%?,En?85.3⁹7.15%?,Fs?2.50¹0.35%?are all enstatite,and the monoclinic Mg^#values?90⁹6?in the pyroxene peridotite are higher are diopside.3.The crystallization temperature of pyroxene is between 1090 and 1230°C,and the average crystallization temperature is 1165°C.The value of amphibole Ca/?Ca+Na+K?is used to calculate the pyroxene AI^? and Cr distribution thermometers.The formation temperature of hornblende originating from the magma is between 670⁸00°C.The formation temperature of the hornblende formed at metasomatism is between 535⁷01°C.4.The zircon U-Pb dating results show that the age of zircon trapped in the peridotite peridotite is 208 Ma.This age is consistent with the crystallization age of the Yingyun diorite in the Qingta Mountain,which constrains the age of its formation,that is,at the same time or later than The age.According to the Zr/Y-Ti/Y diagram,the tectonic setting of this area shows that the serpentine pyroxene peridotite,serpentine schist and hornblende igneous rock in this area were all deposited on the edge of the plate;The TiO₂/10-MnO-P₂O₅ diagram shows that the Yanbishan mafic rocks were incorporated into island-arc flared basalts and calc-alkaline basalts suggesting that ultramafic rocks and mafic rocks may form in arc environments.5.Yanbishan ultramafic rocks are the Earth's melting high-magnesium tholeiitic basaltic magma melted after the crystallization of magma and the formation of ultramafic heterogeneity.The ultra-mafic rocks exposed in YanBishan mountain from the petrological characteristics,rock geochemical characteristics,mineral chemical characteristics,and chronological studies revealed in the Yanbishan area are ultramafic rocks in the SSZ ophiolite.