Stratigraphies and chronologies of late Quaternary loess–paleosol sequences in the core area of the central Asian arid zone

The sporadic distribution of the Quaternary loess in Central Asia makes it hard to establish a regional pedostratigraphy through visual tracing of marker strata. The pedostratigraphic correlation presented here is thus completely based on the radiocarbon chronologies of the four studied sections. The first noticeable feature is that poorly-drained conditions predominated in the period between ∼48,000 and ∼30,000 14C BP, during which three entisols developed at ∼45,000 14C BP, ∼40,000 14C BP, and ∼35,000 14C BP. After a period of loess deposition between ∼30,000 and ∼18,000 14C BP under poorly-drained conditions, an entisol at the westernmost site (Valikhanov, south-central Kazakhstan) developed between ∼18,000 and ∼10,000 14C BP, also under poorly-drained conditions. The time equivalent deposits at Romantic and Zeketai sections to the east do not exhibit any soil-forming characteristics, although poorly-drained conditions are also imprinted in the time-equivalent loess. The Holocene sequences in the Central Asian domain consist of an early Holocene loess unit deposited between ∼10,000 and ∼5,000 14C BP and a late Holocene soil formed during the past ∼5000 years. In comparison, the climate was also wet between ∼48,000 and ∼20,000 14C BP, during which three mollisols developed under well-drained conditions in the Chinese Loess Plateau of the East Asian domain. The loess deposited between ∼23,000 and ∼10,000 14C BP in the Chinese Loess Plateau has neither observable marks of soil formation nor imprints of poorly-drained conditions. The Holocene sequence in the East Asian domain exhibits an out-of-phase relationship with that in the Central Asian domain, consisting of an early Holocene soil formed between ∼9000 and ∼4000 14C BP and a late Holocene loess unit deposited during the past ∼4000 years.