Early Pleistocene climate in north Iran and its correlation with EasternAsia

Arid central Asia (ACA) constitutes the largest extra-tropical arid zone on our planetary Earth. The lack ofin situ early Pleistocene loess/dust records hinders our comprehensive understanding of the spatiotemporalhistory of Asian aridification as a whole. Here, we report the results of sedimentological,chronological and paleoclimatic studies of the early Pleistocene sedimentary sequences from the so-calledIranian Loess Plateau (ILP) in the western part of ACA. Our results indicate that: ۱) the widely distributedred-coloured sediments underlying the upper Pleistocene loess successions in the ILP are actually aeolianin origin; ۲) the main part of the Pleistocene loess in ILP was transported predominantly by the local lowlevelwinds from proximal source regions, such as the arid Caspian Lowland and the Karakum Desert; ۳)accumulation of loess on the ILP commenced at ~۲.۴-۱.۸ Ma, suggesting dust storms have become frequentin ACA at least since the early Pleistocene; ۴) the climate during the early Pleistocene in the ILP was semiarid,but wetter, warmer, and less windy than during the late Pleistocene and present interglacial; ۵) orbitalscalepalaeoclimatic changes in ACA during the early Pleistoceneare in-phase with those of monsoonalAsia, a relationship which was probably related to the growth and decay of northern hemisphere ice sheets.