摘要
下三叠统幸福之路组分布于大兴安岭南部,为一套以红层为主要特征的杂色碎屑岩组合,时代为早三叠世。笔者重新实测了幸福之路组三段建组剖面——巴林右旗幸福之路苏木哈拉山东剖面,除采集到早三叠世早期的孢粉、叶肢介等化石外,在剖面下部首次发现了凝灰岩夹层。采用LA-ICP-MS技术,对2个凝灰岩中的锆石进行了U-Pb年龄测定,获得的年龄值为252.6±1.7Ma(MSWD=0.64)和249.9±1.6Ma(MSWD=0.22),即火山岩大约在250Ma前形成。结合地层古生物及区域岩浆岩资料,认为幸福之路组三段的形成时代为早三叠世早期,大兴安岭南部存在约250Ma与板块闭合相关的岩浆事件,以红层为特色的幸福之路组含有华夏和安加拉两大植物群混生的孢粉化石组合,反映华北板块与西伯利亚板块在250Ma时已经完成碰撞拼贴,幸福之路组形成于碰撞之后。
The Xingfuzhilu Formation, previously defined as Early Triassic strata, is distributed in southern Da Hinggan Mountains. The Lower Triassic strata are offluvial-lacus-trine facies with red-bed features. The stratotype of the third member of the formation was reinvestigated by the authors. The age of the stratotype section is early Early Triassic, as evidenced by the newly-discovered conchostracans, pollen and spores. The volcanic tufts of the lower part of the section were discovered for the first time. LA-ICP-MS dating of two tuffsamples yielded ages of 252.6_ 1.7Ma（MSWD=0.64） and 249.9± 1.6Ma（MSWD=0.22）. In combination with the biological characteristics, geographical division and timing of the magmatism, it is concluded that the Xingfuzhilu Formation characterized by fluviallacus-trine facies and red beds was formed by the collisional collage of the North China Platform with the Siberia Plate in Early Triassic.
出处
《地质通报》
CAS
CSCD
北大核心
2014年第2期370-377,共8页
Geological Bulletin of China
基金
中国地质调查局项目(编号:1212010782001
1212011121086和1212011120970)
