地质通报2016，Vol.35Issue(6)：906-918,13.
大兴安岭中段塔尔气地区流纹岩年龄、地球化学特征及其地质意义
Geochronological and geochemical characteristics of the rhyolites in Taerqi of middle Da Hinggan Mountains and their geological significance
摘要
Abstract
Taerqi area is located in the middle main ridge of Da Hinggan Mountains, where there is developed a suite of late Mesozo⁃ic volcanic rocks, which include basalt, andesite, dacite, rhyolite and tuff. In this paper, detailed LA-ICP-MS zircon U-Pb geochro⁃nological and element geochemical studies were carried out for the rhyolites. The zircon U-Pb dating yielded a weighted average age of 132 ± 2Ma(MSWD=1.5,2σ), indicating that the rhyolites were formed at the middle stage of the early Cretaceous. Rock geo⁃chemical characteristics show that the rocks are peraluminous cal-alkaline rhyolites, which are characterized by high SiO 2 (71.6%~77%), high potassium and alkali content (K2O=4.5%~5.46%, Na2O+K2O=7.94%~9.64%). Trace elements have a similar variation trend that systematic enrichment of LILE and depletion of HFSE as well as LREE fractionation are more obvious than that of HREE, and also show significant weak anomaly of Eu (δEu=0.22~0.7). In addition, there exist the depletion of Sr, Ba, P, Ti, Nb, Ta and en⁃richment of Rb, K, Th, U, Zr, Hf. The rocks belong genetically to A type with a high zirconium saturation temperature (TZr=842°C) , and the magma source was probably similar to the metagrewacks. Accordingly, it is inferred that the A-type rhyolites were products of partial melting of the crust and formed in a post-collision environment and an extensional tectonic setting.关键词
大兴安岭中段/塔尔气地区/锆石U-Pb年龄/A型流纹岩/后碰撞Key words
middle Da Hinggan Mountains/Taerqi area/zircon U-Pb dating/A-type rhyolites/post-orogenic分类
地质学引用本文复制引用
李杰,吕新彪,陈超,衮民汕,杨永胜,徐益群,王琳,张帅..大兴安岭中段塔尔气地区流纹岩年龄、地球化学特征及其地质意义[J].地质通报,2016,35(6):906-918,13.基金项目
中国地质调查局项目 （）
