西天山造山帶及古生代構(gòu)造演化與地殼增生：來自花崗-全文預(yù)覽
【正文】 he Central Tianshan plate and towards north under the Yili plate simultaneously. In the early stage of Late Ordovician, the Terskey Ocean had been closed, and the Yili and Central Tianshan plates collided. Meanwhile, extension happened within the joint Central Tianshan and Tarim plates gradually and the PaleoSouth Tianshan Ocean had been formed. In Early Silurian, the PaleoSouth Tianshan Ocean began to subduct beneath the posite YiliCentral Tianshan plate, which was intruded by volcanic arc granitoids. In Middle Silurian, the PaleoSouth Tianshan Ocean, which had reached a certain width, was subducting strongly. And this subduction may have produced voluminous granitoids in the Central Tianshan plate. In the latest stage of Carboniferous, the PaleoSouth Tianshan ocean closed, and the YiliCentral Tianshan plate and Tarim plate collided. In Late Cambrian, PaleoJunggar Ocean occurred to north of the Yili plate。rzburg, Am Hubland 97074, W252。Sr、Nd同位素特征綜合顯示西天山造山帶花崗巖形成的源區(qū)并不單一，是殼源和幔源巖漿混合而成。晚石炭紀(jì)，古準(zhǔn)噶爾洋閉合消失。早志留紀(jì)，古南天山洋開始向伊犁中天山板塊之下俯沖，形成火山弧型花崗巖。479Ma~321Ma的花崗巖大多為鎂質(zhì)鈣性堿性巖，少數(shù)為鐵質(zhì)鈣堿性堿性巖，它們表現(xiàn)為大陸弧花崗巖的特征，少量形成于276Ma~247Ma間的后碰撞花崗巖一定程度繼承了先存巖漿弧的特征；南天山（塔里木板塊北緣）花崗巖形成于420Ma~411Ma和285Ma左右兩個(gè)階段，420Ma~411Ma間的鎂質(zhì)鈣性堿性巖花崗巖，可能為拉伸環(huán)境下的產(chǎn)物，285Ma花崗巖主要為鐵質(zhì)鈣堿性堿鈣性巖，SiO2 含量高、全堿含量高、表現(xiàn)明顯的Eu，Ba，Sr，P，Ti的負(fù)異常，具有類似于A型花崗巖的地球化學(xué)特征，它們形成于后碰撞造山過程中的拉伸環(huán)境。花崗巖的形成分為兩個(gè)階段：896Ma的花崗片麻巖反映了前寒武紀(jì)基底巖系的形成時(shí)間，470Ma~247Ma間的花崗巖記錄了西天山古生代造山過程。西天山造山帶位于中亞造山帶的西南緣，其對(duì)認(rèn)識(shí)中亞造山過程和大陸地殼增生具有重要意義。西天山造山帶的古生代構(gòu)造演化與地殼增生：來自花崗巖的證據(jù)龍靈利1, 高俊1, 錢青
規(guī)章制度相關(guān)推薦
鄂ICP備17016276號(hào)-1