發(fā)布時(shí)間：2018-12-11 19:22

【摘要】：新疆東天山哈爾里克造山帶火山巖為一套酸性—基性巖(流紋巖、英安巖、安山巖、玄武巖)夾火山碎屑巖(凝灰?guī)r)的巖石組合。流紋巖樣品的LA-ICP-MS鋯石U-Pb定年結(jié)果顯示,時(shí)代為中奧陶世大坪期((468.8±9.1)Ma),代表了該套火山巖的形成年齡。巖石地球化學(xué)分析結(jié)果顯示,該套火山巖SiO_2含量介于49.12%~78.24%,TiO_2介于0.12%~1.00%,Al_2O_3介于11.31%~20.86%;鋁飽和指數(shù)A/CNK值為0.80~1.31(均值為0.99),里特曼指數(shù)σ值為0.19~3.86(均值為1.29),Mg#值為8.87~49.29(均值為31.20);富集大離子親石元素(LILE)Ba、Rb以及輕稀土元素(∑LREE)La、Ce,虧損高場(chǎng)強(qiáng)元素(HFSE)Nb、Ta、Ti等。微量元素和稀土元素的相關(guān)圖解與比值以及發(fā)育的捕獲鋯石反映了俯沖帶島弧鈣堿性火山巖特征,且存在大陸地殼混染作用。綜合區(qū)域地質(zhì)資料分析,在早古生代期間(中奧陶世—早志留世),哈爾里克造山帶存在大面積的與島弧演化有關(guān)的加里東期巖漿活動(dòng),此期間哈爾里克造山帶的構(gòu)造背景為洋殼俯沖有關(guān)的島弧環(huán)境,其形成可能與東準(zhǔn)噶爾南部克拉麥里洋向南俯沖作用有關(guān)。
[Abstract]:The volcanic rocks of the Hallik orogenic belt in eastern Tianshan, Xinjiang are a set of acid-basic rocks (rhyolite, dacite, andesite, basalt) with volcanic clastic rocks (tuff). The LA-ICP-MS zircon U-Pb dating of rhyolite samples shows that the age is the Daping stage of the Middle Ordovician (468.8 鹵9.1) Ma),) representing the formation age of this set of volcanic rocks. The results of petrogeochemical analysis show that the SiO_2 content of the volcanic rocks is between 49.12 and 78.24 and TiO-2 is between 0.12 and 1.00. The number of Al2O3 is between 11.31 and 20.86; The A/CNK value of aluminum saturation index is 0.80 ~ 1.31 (mean = 0.99), the 蟽 value of Ritman index is 0.19 ~ 3.86 (mean = 1.29), and the Mg# value is 8.87 ~ 49.29 (mean = 31.20). The enrichment of large ion lithophile element (LILE) Ba,Rb and light rare earth element (鈭，

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