Micromorphological and geochemical evidence of climate variations in the southern Loess Plateau of China during the last 10000 years

Holocene polycyclic soils were discovered in the southern Loess Plateau, China. The Wulipu Holocene loess profile was studied by field and micromorphological methods; in addition, the magnetic susceptibility, grain-size distribution, total organic matter, and the content of trace elements were determined. Claying horizons were identified in the soil, and calcification was obvious in the loess layer in the profile. This suggests that the Holocene paleosols SO2 and SO1 were formed in a warm and wet forest environment. Because of the deposition of a loess layer (Lx) during the aridity interval between 6000 and 5000 BP, the paleosol SO, normally associated with the Holocene Megathermal period, was separated into two distinct soils, namely SO2 and SO1. Studies indicate that the lower soil (SO2) was formed in the warmest and wettest phase of the Holocene, with the strongest pedogenesis between 8500 and 6000 BP. The upper soil (SO1) was developed in another warm and wet phase with somewhat lower precipitation between 5000 and 3100 BP. It has been a relatively and climate since 3100 BP, which accelerated eolian dust deposition. A layer of 40- to 60-cm-thick loess was accumulated on the southern Loess Plateau, and thus the soil complex SO was buried and became a paleosol of the Holocene.