Late Cenozoic climates of low-latitude East Asia: A paleobotanical example from the Baise Basin of Guangxi, southern China

A middle Pleistocene flora from a low latitude of southern China was paleoclimatically studied through a quantitative reconstruction. The fossiliferous layer is correlated to the fourth terrace of the local Youjiang River and its age is revised to be the middle Pleistocene based on the presence of Paleolithic stones in the fourth terrace. The Coexistence Approach was applied to the plant fossil materials, combined from both leaf fossils and a sporo-pollen assemblage collected and extracted from the Changsheling Formation. The reconstructed temperatures show that southern China was slightly cooler in the middle Pleistocene than today, which is consistent with the global middle Pleistocene cooling trend in the Quaternary. The mean annual range of temperature from the fossil site appears larger compared to present, implying a somewhat higher seasonality of temperature in the middle Pleistocene. The reconstructed rainfall pattern suggests that the low latitude region in southern China experienced a relatively low rainfall seasonality resulted from the impact of weaker-than-present winter and summer East Asian monsoons during the middle Pleistocene. Furthermore, this overall wetter condition throughout the year during the middle Pleistocene transition provides additional evidence to support the conclusion from other coeval terrestrial records such as vermiculated red soils across southern China. The cooler-than-present temperature and reduced summer precipitation at the fossil site may indicate that the fossil site belongs to a glacial phase.