Early Pleistocene climate in western arid central Asia inferred from loess-palaeosol sequences

Abstract

Arid central Asia (ACA) is one of the most arid regions in the mid-latitudes and one of the main potential dust sources for the northern hemisphere. The lack of in situ early Pleistocene loess/dust records from ACA hinders our comprehensive understanding of the spatio-temporal record of aeolian loess accumulation and long term climatic changes in Asia as a whole. Here, we report the results of sedimentological, chronological and climatic studies of early Pleistocene loess-palaeosol sequences (LPS) from the northeastern Iranian Golestan Province (NIGP) in the western part of ACA. Our results reveal that: 1) Accumulation of loess on the NIGP commenced at ~2.4–1.8 Ma, making it the oldest loess known so far in western ACA; 2) the climate during the early Pleistocene in the NIGP was semi-arid, but wetter, warmer, and less windy than during the late Pleistocene and present interglacial; 3) orbital-scale palaeoclimatic changes in ACA during the early Pleistoceneare in-phase with those of monsoonal Asia, a relationship which was probably related to the growth and decay of northern hemisphere ice sheets.

Constraining the timing of palaeosol development in Iranian arid environments using OSL dating

“…Kemp et al, 2006), aeolian (e.g. Wang et al, 2016), marginal marine strata and even glacial deposits (e.g. Mahaney et al, 2013) are reliable indicators for stablishing a chronostratigraphic subdivision and correlation with marine isotope stages (MIS) and glacialinterglacial cycles (e.g.…”

Holocene Moisture Variations in Western Arid Central Asia Inferred From Loess Records From NE Iran

“…Land use in the arid‐semiarid northern region is pasture, and in the humid‐subhumid southern region close to the Alborz Mountains rainfed agriculture is practiced (Khormali & Kehl, ). At present, most of the precipitation in the area falls during winter and spring, which accounts for ~85% of the annual total (Wang et al, , Wang, Wang, et al, 2019). Thus, the area has the characteristics of a Mediterranean‐type climate, with hot and dry summers and mild and humid winters (Wang, Wang, et al, 2019).…”

“…The water vapor transport to NE Iran is carried by the high‐level westerlies, sourced from the North Atlantic, Mediterranean, Black Sea, and Caspian Sea (Ballato et al, ). Because of pressure differences between the Caspian Sea and the Central Iranian highlands, northeasterly to northwesterly winds are the dominant near‐surface winds in summer, with the opposite pattern of circulation occurring in winter (Figure b; Wang et al, ; Wang, Wang, et al, 2019). Currently, the mean annual temperature (MAT) varies only slightly, from ~15°C in the south to ~18°C in the north.…”

“…Most of these studies show that the climate variations are in‐phase with those of monsoonal Asia on orbital timescales and out‐of‐phase on suborbital timescales. However, studies of Iranian loess in western ACA have focused mainly on chronology (e.g., Lauer et al, ; Wang et al, ) and edaphology (e.g., Kehl, ; Taheri et al, ). The lack of detailed paleoenvironmental studies of Iranian loess for the interval since the last interglacial, and especially the Holocene, has limited our understanding of the paleoclimatic record of western ACA.…”

Freshwater mollusks from Neogene-Quaternary Dniester and Prut riverine deposits as indicator paleoenvironments: chemical composition of shells and its palaeoecological interpretation

“…Lower resolution methods are used to reconstruct paleoecological conditions of the geological past. There are numerous examples of such usage of geochemical data (Jass et al 2002, Kieniewicz and Smith 2007, Wang et al 2016. Based on this, an application of geochemical methods to fossil shells of freshwater bivalve mollusks from Neogene-Quaternary localities in the south of the Russian Plain was undertaken in this research.…”