Plio-Quaternary stepwise drying of Asia: Evidence from a 3-Ma pollen record from the Chinese Loess Plateau

A 3-Ma pollen record was obtained from a continuous red clay- loess-paleosol sequence at Chaona in the central Chinese Loess Plateau (CLP). The record shows a permanent change of a domination of typical Cupressaceae forest vegetation representative of an ecological environment with a relative warm and humid climate during 3.0-2.6 Ma to largely steppe vegetation under dry climate conditions after 2.6 Ma. The later is further manifested itself as steppe to forest or forest-steppe (spruce forest - mostly mesophilous herbs) between 2.6 Ma and 1.5 Ma, forest-steppe (pine-grass) between 1.5 Ma and 0.95 Ma, open forest-steppe (mesophilous and xeromorphic herbs-pine) between 0.95 Ma and 0.5 Ma, and steppe (xeromorphic herbs) after 0.5 Ma, suggesting a process of stepwise aridification in Central Asia at the late Pliocene and the Quaternary. (c) 2007 Elsevier B.V. All rights reserved.