A Study on the Eocene Flora in Yilan County,Heilongjiang, China

This paper reports the fossil flora in the Yilan Coal Mine, Heilongjiang Province.The Paleogene flora of the Dalianhe formation includes two groups according to their geology column:one (flora A) is from sand-shale above the lower coal seams and the other (flora B) is from oil shale above the upper coal beds. The flora contains two species of pteridophytes, 10 species of gymnosperms and over 40 species of angiosperms including 1 new species and 10 uncertain species, assigned to 49 genera and 35 families. The analysis of the floristic composition and their foliar physiognomy showes that the flora A consists of elements in evergreen broad-leaved and deciduous broad-leaved forests indicating its subtropical feature, whereas the flora B consists of elements in deciduous broad-leaved forests indicating a warm-temperate feature. Compared to the Paleogene floras of Northeastern Asia and North America, the flora A is assigned to the early Eocene, and the flora B to the late Eocene. These results seem to indicate that in the Eocene, paleoclimatic decline took place in Northeast China.