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新疆东天山哈尔里克造山带火山岩为一套酸性—基性岩(流纹岩、英安岩、安山岩、玄武岩)夹火山碎屑岩(凝灰岩)的岩石组合。流纹岩样品的LA-ICP-MS锆石U-Pb定年结果显示,时代为中奥陶世大坪期((468.8±9.1)Ma),代表了该套火山岩的形成年龄。岩石地球化学分析结果显示,该套火山岩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%;铝饱和指数A/CNK值为0.80~1.31(均值为0.99),里特曼指数σ值为0.19~3.86(均值为1.29),Mg#值为8.87~49.29(均值为31.20);富集大离子亲石元素(LILE)Ba、Rb以及轻稀土元素(∑LREE)La、Ce,亏损高场强元素(HFSE)Nb、Ta、Ti等。微量元素和稀土元素的相关图解与比值以及发育的捕获锆石反映了俯冲带岛弧钙碱性火山岩特征,且存在大陆地壳混染作用。综合区域地质资料分析,在早古生代期间(中奥陶世—早志留世),哈尔里克造山带存在大面积的与岛弧演化有关的加里东期岩浆活动,此期间哈尔里克造山带的构造背景为洋壳俯冲有关的岛弧环境,其形成可能与东准噶尔南部克拉麦里洋向南俯冲作用有关。
The volcanic rocks of the Haerlike orogenic belt in eastern Tianshan, Xinjiang, are a combination of volcanic clastic rocks (tuffs) of acidic-basic rocks (rhyolite, dacite, andesite and basalt). The LA-ICP-MS zircon U-Pb dating of rhyolite samples shows that the Middle Ordovician Daping Period (468.8 ± 9.1 Ma) represents the age of formation of the volcanic rocks. The results of lithogeochemical analysis show that the volcanic rocks have SiO_2 content ranging from 49.12% to 78.24%, TiO_2 ranging from 0.12% to 1.00%, Al_2O_3 ranging from 11.31% to 20.86%, and aluminum saturation index A / CNK ranging from 0.80 to 1.31 Mean value of 0.99, σ value of Rittman index of 0.19 ~ 3.86 (mean value 1.29), Mg # value of 8.87 ~ 49.29 (average value of 31.20), enrichment of LILE Ba, Rb and LREE Element (ΣLREE) La, Ce, Loss High Field Strength Element (HFSE) Nb, Ta, Ti, etc. The correlation diagrams and ratios of trace elements and rare earth elements as well as the developed captured zircons reflect the island arc-arc calc-alkaline volcanic features of the subduction zone with the continental crust contamination. According to the analysis of regional geological data, during the Early Paleozoic (Middle Ordovician-Early Silurian), there were large-scale Caledonian magmatism related to island arc evolution in the Harrick orogenic belt. During this period, The tectonic setting of the belt is related to the island arc environment related to oceanic subduction, and its formation may be related to the southward subduction of the Kerameimai Ocean in the southern East Junggar.