西准白杨河一带晚泥盆世双峰式火山岩地球化学特征及其对形成于活动陆缘的限定

谢米斯台山南麓白杨河一带发育晚泥盆世火山岩,该套火山岩产于朱鲁木特组中,其火山熔岩由偏酸性流纹岩组及偏基性粗面英安岩组构成,具双峰式火山岩特征。流纹岩组相对高硅、贫碱、富钾、低铝,REE变化较大、强Eu负异常,富集Cs、Rb、U、Th、K等LILE,亏损Nb、Ta、P、Ti等HFSE,低Sr、高Yb,主体具高钾钙碱性S型花岗岩及南岭型花岗岩特征。粗面英安岩组相对贫硅、富碱、富钠、富铝,低∑REE、中等Eu负异常,富集Cs、Rb、Ba、U、K等LILE,亏损Nb、Ta等HFSE,低Sr、低Yb,显示高钾钙碱性准铝质I型花岗岩特征及喜马拉雅型花岗岩特征。研究表明,白杨河一带晚泥盆世火山岩形成环境为活动陆缘,是西准噶尔地区构造演化研究的重要依据。

Geochemical characteristics of Late Devonian bimodal volcanic rocks in Baiyanghe area, West Junggar and its restriction on formation in active continental margin

The research level of Late Devonian volcanic rocks in West Junggar is relatively low. Choosing Late Devonian volcanic rocks of Zhulumute Formation the Baiyanghe area as the study object, this paper studies the geochemical characteristics and tectonic significance. The Late Devonian volcanic rocks of the study area is characterized by bimodal volcanic rocks, which is combined by rhyolite formation and trachyte dacite formation. The rhyolite formation is characterized by high-K calc-alkaline peraluminous S-type granite and Nanling-type granite. The trachyte dacite formation is characterized by quasi-aluminous high-K calc-alkaline peraluminous S-type granite and Himalaya-type granite. The research shows that Late Devonian volcanic rocks of the study area is formed in the continental margin arc environment.