大兴安岭南部二叠纪-三叠纪之交孢粉化石及古气候环境分析

Discovery and Paleoclimatic Significances of Permian-Triassic Sporopollen Fossils from Southern Da Hinggan Mountains

大兴安岭南部巴林右旗幸福之路苏木查干布拉格村老龙头组(原幸福之路组模式)剖面首次发现孢粉化石18属21种,以Cyclogranisporites sp.,Alisporites parvus De Jersey,Alisporites circulicorpus Clarke,Sulcatisporites rhombicus Qu,Lueckisporites virkkiae R.Potonie et Klaus,Piceites sp.为主。通过典型属种对比,结合已发现的动植物化石、孢粉组合及同位素测年结果分析,确定幸福之路地区老龙头组的时代为晚二叠世-早三叠世,即二叠系-三叠系界限存在于这套陆相连续沉积内部。孢粉化石的亲缘母体以发育种子蕨纲和松柏纲的针叶植物为主,指示当时研究区处于暖温带的干旱-半干旱的古气候环境。

A total of 21 species of the 18 genera sporopollen fossils are discovered for the first time from the section of the Laolongtou Formation (stratotype section of Xingfuzhilu Formation) in Chaganbulage Village, Xingfuzhilu Town, Bairin Right Banner, Southern Da Hinggan Mountains, including Cyclogranisporites sp., Alisporites parvus De Jersey, Alisporites circulicorpus Clarke, Sulcatisporites rhombicus Qu, Lueckisporites virkkiae R. Potonie et Klaus, Piceites sp., et al. Comparing the typical members with the contemporaneous sporopollen assemblages, and combining with the research results,such as the fauna, flora, sporopollen assemblages and LA-ICP-MS zircon geochronology, the Laolongtou Formation should be formed in the Latest Permian to Early Triassic. The botanical affinities of the sporopollen fossils mainly consist of conifers, belonging to a dry-semi arid and hot-worm climate environment prevailing from the Latest Permian to Early Triassic in Xingfuzhilu area.