Magnetic properties of surface soils in the Chinese Loess Plateau and the adjacent Gobi areas, and their implication for climatic studies

• Published in: Journal of arid environments Vol. 78; pp. 73 - 79
• Main Authors: Xia, D.S., Jia, J., Wei, H.T., Liu, X.B., Ma, J.Y., Wang, X.M., Chen, F.H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2012; Elsevier
• Subjects: Alxa plateau; Animal and plant ecology; Animal, plant and microbial ecology; arid zones; Biological and medical sciences; environmental indicators; Environmental magnetism; Fundamental and applied biological sciences. Psychology; Grain size; Loess; Loess plateau; loess soils; Magnetic permeability; magnetic properties; Magnetic susceptibility; magnetite; Minerals; plateaus; Precipitation; soil properties; soil sampling; Soils; Surface soil; Synecology; Terrestrial ecosystems; topography; Weight loss; China, People's Rep., Loess Plateau; China, People's Rep; Environmental magnetism; Precipitation; Loess plateau; Surface soil; Alxa plateau; Climatic condition; Loess; Soils; Climate; Arid environment; Property of soil; Chinese Loess Plateau
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2011.10.012

Sixty-two surface soil samples, collected along a precipitation gradient in the Loess Plateau and the Alxa Plateau area, northwest China, were analyzed using environmental magnetic parameters (χlf, χfd%, χARM, SIRM, HIRM, SOFT, and back field IRM), grain size, and weight loss on ignition. The results show that the magnetic mineral assemblage in the surface soil is dominated by magnetite and maghemite, with some hematite. Cross plots of χfd% vs. χARM/SIRM indicate that the main magnetic grain sizes in the surface soils are pseudo single domain (PSD) and multidomain (MD). The samples from the Alxa area are dominated by magnetic minerals with a larger grain size while those from the Loess Plateau are dominated by magnetic minerals with a finer grain size. The main magnetic minerals in the surface soil of the Loess Plateau originate from both the aeolian dust and pedogenic processes, with the later dominating. Compared to magnetic susceptibility, frequency-dependent magnetic susceptibility has a stronger correlation with precipitation in this large area of complex geology and topography. This result is not consistent with previous studies and we suggest that caution is needed when using magnetic susceptibility as an indicator of environmental change in arid regions.
► Surface soil from Loess Plateau and the Alxa Plateau area of northwest China were analyzed by using magnetic techniques. ► The main magnetic minerals in the surface soils are magnetite, maghemite and hematite with the grain sizes of PSD and MD. ► The results indicate χfd% has a closer relationship with precipitation than χlf in the study area.