贺兰山上三叠统上田组植物化石研究

Research on fossil plants of Late Triassic Shangtian Formation in the Helan Mountain

对贺兰山地区上田组的植物化石开展研究,此次鉴定出12属14种,结合前人资料,上田组植物化石共计20属35种。其中,真蕨纲和种子蕨纲9属19种,占54%;苏铁纲4属6种,占17%;楔叶纲1属4种,占11%;松柏纲3属3种,占9%;银杏纲2属2种,占6%;分类位置不明的种子1属1种,占3%。该地区植物化石组合以中国北方型Danaeopsis-Bernoullia植物群的属种占主导地位,同时混生了中国南方型Dictyophyllum-Clathropteris植物群的分子Dictyophyllum,且苏铁类占一定的比例,反映了晚三叠世末期贺兰山为半干旱的亚热带大陆型气候,且正在向湿热发展。

In this paper, the fossils of the Shangtian Formation in the Helan Mountain area were studied, and 14 species of 12 generawere identified. In combination with the data provided by previous researchers, there are 35 species of 20 genera in the ShangtianFormation, which include Filicopsida and Spermatophyta of 19 specie in 9 genera, Cycadopsida of 6 species in 4 genera, Sphenopsidaof 4 species in 1genus, Coniferae of 3 species in 3 genera, Ginkgopsida of 2 species in 2 genera. Many plants have the characteristics of Danaeopsis - Bernoullia flora belonging to northern provinces of China, but some species of southern provinces in China and Cy.cadopsida were also found in this flora. Studies show that the Helan Mountain was dominated by a semi-arid subtropical continentalclimate in the late Late Triassic, which was developed towards humid heat.