Geochemistry of loess deposits in northeastern China: constraint on provenance and implication for disappearance of the large Songliao palaeolake

Abstract

The Harbin loess, typical of the loess in NE China, is located in the easternmost margin of the Eurasian loess belt, and was recently investigated from the perspective of an Asian aeolian dust system. Before this study, the geochemical composition and provenance of the Harbin loess remained poorly understood. More importantly, the study of the Harbin loess also provides a unique opportunity to understand the geomorphological evolution process of the large Songliao palaeolake in the Northeast Plain. This study presents the results on the geochemical characteristics (major elements, trace elements, rare earth elements and Sr–Nd isotope) of the Harbin loess. There are markedly consistent geochemical compositions in and between the loess and palaeosol sediments, revealing stable dust sources and identical sources for the loess and palaeosol. Various indicators illustrating weathering and recycling indicate that the Harbin loess–palaeosol sediments were derived from sources with a low degree of weathering and from material with first-cycle alluvial–lacustrine deposits. Combinations of various provenance tracing indicators indicate that the Harbin loess has a strong geochemical affinity with the Songnen Sandy Land and to a certain extent the Horqin Sandy Land but not with the Hulun Buir Sandy Land, which indicates that these loess deposits are derived from a mixed provenance, with the dominant source being the neighbouring Songnen Sandy Land and a second, distal source being the Horqin Sandy Land. Finally, we advocate that the Harbin loess accumulation could serve as the direct record of the Songliao palaeolake disappearance. Supplementary material: Data for the NE Sandy Lands of China, and full provenance discrimination diagrams are available at https://doi.org/10.6084/m9.figshare.c.3835009 .