Reconstruction of paleovegetation and paleoclimate in the Early and Middle Eocene, Hainan Island, China

摘要

The Early-Middle Eocene palynoflora and paleoclimate of Changchang Basin, Hainan Island, South China, is described in the present paper and is compared with that of the Middle-Late Eocene, Hunchun City, Jilin Province, North China. The nearest living relatives (NLRs) of the recovered palynotaxa suggest a subtropical evergreen or deciduous broad-leaved forest at the center of the basin but a temperate evergreen or deciduous broad-leaved forest and needle-leaved forest growing in the peripheral part of the basin. Based on the climatic preferences of the NLRs, the climate in the Changchang Basin during the Early-Middle Eocene was warm and humid subtropical with a mean annual temperature of 14.2-19.8A degrees C, a mean temperature of the warmest month of 22.5-29.1A degrees C, a mean temperature of the coldest month of 1.7-11.9A degrees C, a difference of temperature between coldest and warmest months of 12.1-24.6A degrees C, a mean annual precipitation of 784.7-1,113.3 mm, a mean maximum monthly precipitation of 141.5-268.1 mm and a mean minimum monthly precipitation of 6.9-14.1 mm. A comparison of the palynoflora and paleoclimate between the Changchang Basin and Hunchun City, suggests essentially a similar climate in South and North China during Eocene time in contrast to the oceanic tropical climate in South China and cool dry temperate climate in North China as at present.