Abstract:

It is the very first time to analyze and study the paleoflora of Emuerhe Group in the research area systematically and describe the major component characteristics of each plant category. The paleoflora is composed mainly of ancient ferns and seed plants, among which, ferns amount to 8 genus 15 species, containing Filicophyta and Sphenophyta; seed plants add up to 15 genus 29 species, contain Ginkgophyta, Cycadophyta and Coniferophyta. Plant fossil assemblage of Emuerhe Group bears the following characteristics:(1)Coniopteris has high diversity and abundance; (2) the classic Coniopteris burejensis and Eboracia lobifolia in Middle Jurassic have been found; (3) the simultaneous abundant appearance of Coniopteris,Cladophlebis,Eboracia is the prime feature of the paleoflora in the area. The above characteristics indicate that the Paleoflora belongs to the late ConiopterisPhoenicopsis flora in Middle Jurassic. According to the comprehensive analysis on longitudinal distribution and combined features of the paleoflora in Emuerhe Group, the late flora combination ConiopterisPhoenicopsis can be divided into 3 subcombinations which are ConiopterisNilssonia in Xiufeng Formation, ConiopterisCzekanowskia in Ershierzhan Formation and Coniopteris burejensisCladophlebis cf.asiatica in Mohe FormationKaikukang Formation. The study on paleoflora in Emuerhe Group not merely enriches the biostratigraphic data in the study area and identifies the geological age of Emuerhe Group which belongs to the Middle Jurassic,but more importantly solves the current basic geological problem of exploration of gas hydrate.

Key words: paleoflora, fossil assemblage, Emuerhe Group, Jurassic, Mohe Basin