Denis Rancourt
MZ Dang, DG Rancourt, G Lamarche, ME Evans, H Kodama, AR Mermut, JK Torrance
Clays for Our Future. Proc 11th Int’l Clay Conf, Ottawa, Canada, 1999, 309-315
Description
We have used several complementary techniques to perform mineralogical, chemical, and magnetic characterizations of samples from the S3/L4 couplet of the loess/paleosol section at Baoji, China. Our approach combines: powder X-ray diffraction, X-ray fluorescence analysis, light element analyses, magnetometry, and Fe-57 Mössbauer spectroscopy. We find that the main pedogenic (ie, abundant in S3 but not in L4) oxide that is magnetically ordered at room temperature is not stoichiometric magnetite but that a probable mixture of non-stoichiometric hydrous hematite, maghemite, and some non-stoichiometric (oxidized) magnetite is much more abundant. We also find: a high degree of vertical homogeneity in the original parent material across S3/L4, a more advanced stage of pedogenic development in the paleosol in which the Fe is distributed from the layer silicate minerals to the pedogenic oxides, and pedogenic and paleo-weathering influences on the distributions of Ca, P, C, Na and K.
