Magnetic Proxy of Eurasian Loess Revealing Enhanced Physical Erosion Since the Mid‐Pleistocene Transition

• Published in: Geophysical research letters 2023-07, Vol.50 (13), p.n/a
• Main Authors: Ning, Wenxiao, Zan, Jinbo, Heller, Friedrich, Fang, Xiaomin, Zhang, Yuao, Zhang, Weilin, Kang, Jian, Shen, Miaomiao
• Format: Article
• Language: English
• Subjects: Atmospheric particulates; Bicarbonates; Cenozoic; Climate change; continental erosion; Deposits; Dithionite; Dust; Erosion processes; Eurasian loess; Extraction procedures; Fluvial deposits; Glacial erosion; Glaciers; Global climate; Ice volume; Information processing; Information retrieval; lithogenic susceptibility; Loess; Magnetic properties; Magnetic signals; Magnetite; Mathematical analysis; Mountainous areas; Mountains; Pleistocene; Pleistocene climates; Quaternary; River erosion; Rivers; Sequences; Silicates; Susceptibility; Tectonics
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL104411

Eolian loess deposits contain valuable information about past climate changes and erosion history in dust source regions. In contrast to the extensive investigations of paleoclimatic implications of Eurasian loess, continental erosion information in the loess deposits has received less attention, particularly on the global or hemispheric scales. The present study combines citrate‐bicarbonate‐dithionite (CBD) magnetic mineral extraction procedures and linear regression of magnetic parameters to analyze Eurasian loess. We find that lithogenic susceptibility of Quaternary loess deposits in Central Asia, Europe and the Chinese Loess Plateau shows synchronous long‐term increases since ∼0.6–0.5 Ma, suggesting intensive glacial erosion and/or river incision to have occurred in the surrounding mountains of dust source regions after the mid‐Pleistocene climate Transition. The dramatic increase in lithogenic susceptibility of Eurasian loess provides new insights into the close relationships between global climate changes and dust source erosion since the late Cenozoic. Plain Language Summary Eolian loess deposits are valuable materials for elucidating the development and mechanisms of dust activities in Eurasia and their links with global climate changes and erosion processes in mountainous areas of dust sources on tectonic and orbital time scales. Continental erosion information retrieved from the Eurasian loess, however, has rarely been reported. A comprehensive analysis of lithogenic magnetic signals in Eurasian loess through mathematical and CBD extraction approaches demonstrates that lithogenic susceptibility of Quaternary loess‐paleosol sequences in Eurasia increased significantly after ∼0.6–0.5 Ma, in coincidence with increasing global ice volume and climatic instability after the mid‐Pleistocene climate Transition (MPT). We suggest that increased ice volume and climate fluctuation amplitudes after the MPT produced vast amounts of fresh Fe‐bearing silicate particles and detrital magnetite in mountainous areas of Eurasia, which can be attributed to a dramatic intensification of glacial erosion and river incision, thereby causing the loess lithogenic susceptibility increase. The results demonstrate that variations in lithogenic magnetic properties of loess deposits can be used to reconstruct the erosional history of main mountains surrounding the dust source regions in Eurasia over geological timescales. Key Points Lithogenic magnetic susceptibility of Quaterna