Variability of the temperature-dependent susceptibility of the Holocene eolian deposits in the Chinese loess plateau: A pedogenesis indicator

We used a partial heating/cooling method (Van Velzen and Dekkers, 1999) for the analysis of representative samples of the Holocene loess of the Chines e loess plateau, in order to investigate magnetic mineralogical changes dur ing thermal treatment. The temperature-dependence of susceptibility (TDS) r esults show significant alteration of magnetic phases during heating and co oling, and provide further evidence that magnetite and maghemite are the do minant ferrimagnetic minerals in the Holocene eolian deposits of the loess plateau. The TDS measurements suggest that the degree of the thermally-indu ced alteration is closely related to pedogenesis, which is a function of cl imate, and thus the alteration itself could be a useful climate indicator. Our TDS results along a NW-SE transect in the loess plateau suggest that st ronger pedogenesis results in higher content of maghemite and greater susce ptibility decrease during thermal treatment. This behavior seems to indicat e that the final product of pedogenic magnetite in Chinese loess and paleos ols is maghemite, which plays an important role in the enhancement of the m agnetic susceptibility of Chinese eolian deposits. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.