J Integr Plant Biol. ›› 1994, Vol. 36 ›› Issue (12): -.

• Research Articles •    

Paleoclimatic Analysis of Paleogene Flora in Yilan County, Heilongjiang

He Chao-xing and Tao Jun-rong   

Abstract: Plant fossils were collected from the sand-shale above the lower coal seam and the upper oil shale above the upper coal seam in the Yilan coal mine, Heilongjiang. The floras contained 2 species of pteridophytes, 10 species of gymnosperms and over 58 species of angiosperms assigned to 46 genera and 34 families. The fossils were divided into two floras, one of which was in lower sand-shale beds, with the age assigned to the Eocene, and the other was in the upper part of oil shales considered to belong to the Oligocene. The floras were complicated in composition and rich in species, and were studied by means of floristic analysis, foliar architectural and physiognomical analysis. The Eocene flora consisted of many evergreen broad-leaved species, which indicated that the flora belonged to north subtropical evergreen broad-leaved forest or subtropical coniferous and broad-leaved mixed forest. The foliar physiognomical analysis of the floristic composition showed that the species with entire leaf margines made up 38.3 percent of the total. The climate in the Eocene was estimated by means of climatic nomogram as follow: The mean annual temperature was 13.2 ℃ and annual temperature deviancy was 20℃. In the Oligocene flora, deciduous broadleaved trees were dominant, which indicated that the vegetation was of temperate deciduous broad-leaved forest or warm temperate coniferous and deciduous broad-leaved mixed forest. The species with entire leaf margines were 30. 8 percent with an estimated mean annual temperature of 11 ℃ and mean annual temperature deviancy of 25 ℃. The floristic aspect and climate in the Paleogene of Yilan region were very different from the present ones.

Key words: Paleoclimatic analysis, Paleogene flora, Climatic nomogram

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