大兴安岭乌奴尔地区白音高老组流纹岩锆石U-Pb年龄及形成地质背景讨论

李利阳; 张传恒; 韩瑶; 石成龙; 刘博; 刘根源

doi:10.12029/gc20200229002

大兴安岭乌奴尔地区白音高老组流纹岩锆石U-Pb年龄及形成地质背景讨论

Zircon U-Pb age and geological background of rhyolite from Baiyingaolao Formation in Wunuer area, Great Xing'an Range

摘要

摘要:
研究目的 大兴安岭分布着中国东北最大的中生代火山岩带，白音高老组是该中生代火山岩重要组成部分，白音高老组的年代学及地球化学特征可为大兴安岭地区构造演化提供基础地质资料。
研究方法 本文对大兴安岭乌奴尔地区白音高老组流纹岩进行了LA-ICP-MS锆石U-Pb测年和岩石地球化学测试。
研究结果 流纹岩锆石U-Pb年龄为（127.6±1.2）Ma，属早白垩世。岩石地球化学数据显示，岩体属高硅高钾弱过铝质钙碱性系列。岩石整体富集大离子亲石元素K、Rb、Ba，亏损大离子亲石元素Sr和高场强元素Nb、P、Ti，LREE相对富集，HREE相对亏损，具有中等的富Eu异常（δEu=0.49~0.87）。
结论综合区域地质特征及本次研究认为，大兴安岭乌奴尔地区白音高老组流纹岩的形成构造背景可能与古太平洋板块向欧亚大陆之下俯冲作用有关。

Abstract:
This paper is the result of geological survey engineering.
Objective The Baiyingaolao Formation is an important part of the Mesozoic volcanic rocks in Great Xing'an Range, Northeastern China, and the geochronology and geochemistry characteristics of the Baiyingaolao Formation can provide basic geological data for the tectonic evolution of Great Xing'an Range.
Methods In this paper, LA-ICP-MS zircon U-Pb age and geochemistry of the rhyolites in Baiyingaolao Formation from Wunuer area in Great Xing'an Range have been carried out.
Results The testing results indicate that the LA-ICP-MS zircon U-Pb crystallization age is (127.6 ±1.2Ma) Ma, which belongs to Early Cretaceous. The rhyolites belong to high-SiO₂, high-K peraluminous, calcalkaline series. The rhyolites are enriched in Rb, Ba, K, depleted in Sr and Nb, P, Ti, and LREE is enriched and HREE is relatively depleted, with moderate Eu-rich anomaly (δEu=0.49~0.87).
Conclusions Combined with regional geological characteristics, the tectonic setting of rhyolites in Baiyingaolao Formation from Wunuer area in Great Xing'an Range may be related to the subduction of Pacific plate.

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