吉林洮南下侏罗统红旗组假篦羽叶的发现

下侏罗统红旗组主要分布在大兴安岭东南部吉林洮南万宝盆地的红旗-碱土一带,由一套含煤的陆源碎屑沉积岩组成,其上与中侏罗统万宝组底砾岩平行不整合接触,其下与中二叠统大石寨组凝灰岩角度不整合接触,属局部山间断陷盆地的湖相、沼泽相沉积.1982年杨学林和孙礼文首次报道了红旗组植物化石,其中缺乏苏铁植物.最近,在红旗组化石研究中,发现了数块伊什假篦羽叶(Pseudoctenis eathiensis)植物化石,伴生植物有拟刺葵和异羽叶等.尽管该组已发现的新芦木、枝脉蕨、假篦羽叶、异羽叶、茨康叶、苏铁杉和松型叶可以和柴达木盆地东北缘下侏罗统植物化石相比较,但假篦羽叶和异羽叶等苏铁植物实际并不丰富,反映了暖温带到"似热带"气候控制下的大陆植物区的植物群特征.这一特征可与热带气候控制下的具丰富苏铁植物的滨海植物区形成明显的对比.

Pseudoctenis DISCOVERED FROM THE LOWER JURASSIC HONGQI FORMATION IN JILIN PROVINCE

The Lower Jurassic Hongqi Formation, distributed mainly in Wanbao Basin of the southeastern Daxinganling Mountains in Taonan, Jilin Province, is predominately composed of coal-bearing clastic sedimentary rocks, overlying the tuffs of the Middle Permian Dashizai Formation with unconformity, and in turn overlain disconformably by the basal conglomerates of the Middle Jurassic Wanbao Formation, representing lacustrine and swamp facies developed on a local intermontane fault basin. In 1982, Yang Xuelin and Sun Liwen first reported fossil flora with occasional occurrence of Cycadophytes from Hongqi Formation. Recently, several fossil leaves of Pseudoctenis eathiensis, associated with Phoenicopsis and Anomozamites, etc. were discovered from Hongqi Formation. Although Neocalamites, Cladophlebis, Pseudoctenis, Anomozamites, Czekanowskia, Podozamites and Pityophyllum are comparable with the Early Jurassic fossil plants from the northeastern border of Qaidam Basin in Qinghai, Cycadophytes including Pseudoctenis and Anomozamites are actually not abundant, indicating that the characteristics of Continental Floristic Province under the control of warm temperate to "paratropical" climate are quite different from those of Maritime Floristic Province under the control of tropical climate, which is characterized by abundant Cycadophytes.