Abstract:

Based on the analysis of major elements, trace elements and geochemical weathering parameters about a representative loess-paleosoil-aeolian sediment profile in the southeast of Maqu Plateau, and combined with ¹⁴C dating, we discuss the chemical weathering process since the middle-late Holocene. Research results prove that: (1) Chemical activity of different geochemical elements in section showed obvious variability, the major elements such as Ca, Si and Na were migrated and leached, while the elements Fe and Mg were obviously enriched, the activity and migration of elements were followed by Ca >Si >Na >Al >K >Fe >Mg; the migration features of the major elements indicated that the profile completed the primary process of chemical weathering characterized by leaching of Ca and Na; During the chemical weathering process, trace elements such as Cu, Mn and Zn were obviously accumulated except Sr. (2) Based on the climate change process from cold-dry-cool-humid-cool-dry to warm-humid recorded by the typical geochemical elements and combined with chemical weathering parameters, the chemical weathering process in the Maqu Plateau since the middle-late Holocene can be divided into four stages. Before 3.8 ka BP, the regional chemical weathering was relatively weaker, while it was relatively stronger from 3.8 ka BP to 3.5 ka BP. During 3.5-1.6 ka BP, the chemical weathering degree obviously became weaker, since then the chemical weathering tended to be stronger.

Key words: geochemical elements, chemical weathering, middle-late Holocene, Maqu Plateau