Geochemistry And Geological Significance Of The Xiaodongshan Volcanic Architecture In The Aqishan Area,Eastern Tianshan,Xinjiang

The Aqishan-Yamansu island arc belt is located in Jueluotage region,which remains vast Carboniferous rock records and paleo-volcanic Architecture due to the closure of the paleo-tianshan ocean and its concomitant subduction and collision in the Carboniferous.The study area in the Aqishan-Yamansu island arc belt is situated in the southern Jueluotage Tectonic zone.Large area Carboniferous magmatic rocks is exposed in the island arc belt.The main research object of this paper is the xiaodongshan Volcanic Architecture in the Aqishan Area and well exposed Carboniferous magmatic rocks and Volcanic Architecture in the Aqishan-Yamansu island arc belt are studied.we use mineralogy,petrology,geochemistry,zircon U-Pb ages and Lu-Hf isotopes to analyse the granite-porphyry,ignimbrites,basalts,andesites and andesitic porphyrites in order to study the regional geological tectonic evolution during the closure of the paleo Tianshan ocean in the Late Carboniferous.Data from samples was analysed and processed.8 studied samples showed metaluminous,intermediate-potassic and calc-alkaline rock features.The primitive mantle-normalized rocks has an enrichment of LILE?K?Rb?Ba?Pb?and radioelements like Th and U.Also the rocks have a loss of high field strength elements?HFSE?like Nb?Ta?P?Ti.The trace element curves standardized by chondrite were inclining overall to the right.Their REE model is characterized by enrichment in light REE other than heavy REE and tiny negative Eu and Ce anomaly.The samples showed characteristics of island arc volcanic rocks overall.Zircon grains from granite-porphyry,ignimbrites,andesites and andesitic porphyrites were dated using U-Pb method.They yielded crystalline ages of 331Ma,333Ma,315Ma and 302Ma,which represented the crystallization time of different Lithofacies zone.This means the eruption age of xiaodongshan volcanic architecture is 331³02Ma.The?_Hf?t?of granite-porphyry,andesites and andesitic porphyrites respectively are+11⁺15?-2.5⁺12.7?-10⁺2,and the corresponding T^C_DM are 0.34⁰.64Ga?0.61⁰.16Ga and 1.44².28Ga The high?_Hf?t?and young T^C_DM are similar to the granites from the Central Asian Orogenic Belt.The?_Hf?t?range is wider compared with middle Tianshan block which has Precambrian basement.This may be related to the recycling of primitive materials.The granite-porphyry could be the product of the subduction-collision process of the Tianshan ocean in the late Carboniferous.The granite-porphyry may also evolve from the dehydration melting metasomatism of new oceanic plate.While the low?_Hf?t?of andesites means this received contamination from crustal materials.Through the analysis of sample data combines with the previous research results of the Aqishan-Yamansu island arc belt.We believe this volcanic architecture formed in the process of Paleo Tianshan ocean closure.The dehydration and melting of the new oceanic crust in the subduction of the oceanic crust.The fluid and melt heating and replacement of the crust in the Tianshan Mountains.The crustal rock group formed by partial melting with island arc environment characteristics...