Abstract:

The Eocene palynoflora from Changchang basin of Hainan Island, China contains 40 genera of 32 families of spermatophyte pollen and 11 genera of 8 families of pteridophyte spore. Analysis of the seed plants of the Eocene palynoflora from the Changchang basin and comparison between the fossil and modern floras from Hainan Island show: (1)On family level, the Eocene palynoflora from Changchang basin is dominated by pantropic plants, count 37.5% of all numbers of families. Tropic-subtropic families only take 6.25%, and subtropic-temperate families count 31.25%. While, for the modern flora in Hainan Island, pantropic families count 48.07%, tropicsubtropic families are as high as 18.88%, and subtropictemperate families count only 15.88%. Obviously, the Eocene palynoflora from Changchang Basin reveals much more subtropical characters. (2)On genus level, the Eocene palynoflora from Changchang basin consists of 7.5% of pantropic genera, 17.5% of tropic-subtropic genera, and as high as 67.5% of subtropic-temperate genera. On the contrast, for the modern flora in Hainan Island, pantropic and tropic-subtropic genera increase substantially, up to 23.9% and 57.5% respectively; subtropic-temperate genera decrease greatly, only 13.7%. Thus, the Eocene palynoflora from Changchang basin is obviously characterized by subtropic-temperate plants, and even some alpine plants, such as Abies and Tsuga, etc. The Eocene temperature in Hainan Island is lower than today according to the composition of plant families and genera,  and there might exist high-altitude mountains surrounding the Changchang basin.

Key words: Eocene, palynoflora, flora, Hainan Island, Changchang basin, Changchang Formation