Geochemical Characteristics And Tectonic Significance Of Ekou Granite In Wutai Area,Shanxi

The formation of acid granite is mainly exposed to acid granite in the Wutai area of Shanxi Province.The formation time is about the same period in the late Archean region.The granite formation on the edge of the rock gneiss is more developed.The granite of the Ekou granite is of special significance to the formation of the North China Craton.In the field investigation of the rocks,the magmatic rocks of the Ekou granite in Shanxi are discussed through the study of the lithology(identification),LA-ICP-MS zircon U-Pb chronology and the whole rock geochemistry of the Ekou granite Source,cause and formation of the construction environment.The formation age of two sets LA-ICP-MA Zircon U-Pb granite intrusions was 2507 ± 53 Ma and 2420 ± 2.5Ma respectively,and the formation time was similar,which was probably formed in the late Archean period which is close to WuTaiorogeny time.Geochemical characteristics show that the intrusion of the rock belongs to the subalenine series of quasi-aluminum-weakly aluminum-rich alkaline granite.LREE / HREE = 1.52 ~ 9.72,with an average value of 5.21,and the rock heavy and light fraction of rare earth elements is strong.LaN / YbN=0.7~10.53,with an average of 3.94,indicating that light rare earth enrichment,heavy rare earth element fractionation smaller.The ?Eu is 0.08 ~ 1.67,with an average value of 0.48,showing a strong negative Eu anomaly,indicating that there is a certain amount of plagioclase in the magma source region.Trace elements peider web can be drawn that enrich such as Rb,Th,K and other large ion lithophile elements,significant loss of Ba,Nb,Sr,P,Ti and other high field strength elements,granite body with significant Nb,Ta trough and loss P,Ti and other high field strength elements,which shows that the magmatic rock is formed in the island arc volcanic environment.According to the above conclusions of geochemical conclusions,in general Ekou rock mass with I-type granite geochemical characteristics.Combined with the geochemical characteristics and tectonic setting of the rock mass,it is shown that the Ekou rock mass is formed in the continental island of the continental margin,and its source area is the melting mixture of the middle and lower crust basalts and oceanic sediments.The oceanic arc is formed by oceanic subduction.Under further subduction,Fracture development of coffin-supine fold,push-ductile ductile shear zone and thrust structure in Fuping land and island arc collision.Accompanied by the intrusion of the Egou rock mass,the development of the greenstone facies-amphibolite facies low temperature dynamic metamorphism..The general layout of the North China Craton is a series of slender volcanic arc geological bodies between the Fuping block and the Hengshan block and the two,which is due to the development of inter-continental block ocean oceanic arc with the SE direction orogenesis superimposed nappe,forming a narrow band towards NNE.This is the earliest orogenic movement in North China Craton,which is the initial stage of the formation of the North China Craton basement.Through the study of the granite rock mass in the Ekou granite,it is shown that the I-type with island arc environment in the continental margin,and it is an indispensable part of the North China Craton Center.