地质通报2016，Vol.35Issue(6)：919-931,13.
内蒙古锡林浩特早白垩世晚期钾玄质火山岩成因及构造环境
Petrogenesis and tectonics of late Early Cretaceous Shoshon-itic volcanic rocks in Xilin Hot, Inner Mongolia
摘要
Abstract
According to the research on zircon dating and cross section, the authors redefined Late Jurassic Manketou Formation as Early Cretaceous Meletu Formation in the southwestern segment of the Da Xinggan Mountains. Volcanic rocks are divided into two kinds of lithology, the lower segment is mainly trachy-andesite with minor trachyte, whereas the upper is trachyte and rhyolite. The zircon U-Pb age of trachyte is 118.1 ± 1.3Ma, suggesting that its formation age is Early Cretaceous. Rocks have rich alkali, rich po⁃tassium, and high aluminum whose value varies in a wide range, high Fe2O3/FeO ratios (>0.5), and relatively rich light rare earth ele⁃ments and LILE (such as Rb, Ba, Th and Pb) but poor high field strength elements (such as Nb, Ta, and P). Rocks have obvious iron-depletion evolution trend in the AFM diagram and"Barbed"evolution trend in the SiO 2-K2O diagram, with conspicuous char⁃acteristics of shoshonites. Studies show that the intermediate acidic volcanic rocks of the Meletu Formation in the study area have magmatic evolution characteristics of the same source region. Magma originated from enrichment of mantle metasomatism and was formed in a stretching tectonic background and related to the retreat of subduction of the Pacific Plate.关键词
大兴安岭西南段/早白垩世晚期/梅勒图组/伸展环境/交代富集地幔Key words
southwestern segment of the Da Hinggan Mountains/late Early Cretaceous/Meletu Formation/extensional environ-ment/metasomatic enriched mantle分类
天文与地球科学引用本文复制引用
王良玉,廖群安,江云川,罗婷,胡朝斌,肖典,汤帅,刘洋..内蒙古锡林浩特早白垩世晚期钾玄质火山岩成因及构造环境[J].地质通报,2016,35(6):919-931,13.基金项目
中国地质调查局项目 （）
