Characterization of Argentine Loess and Paleosols by Mossbauer Spectroscopy

摘要

We have used Mossbauer spectroscopy to investigate iron-bearing mineral samples of loess and paleosols from a geologic section at La Plata, Argentina, 34°54'14" S and 58°2'W. Hematite is by far the dominant iron-bearing magnetic component in initial loess and paleosol samples. The samples were also subjected to magnetic separation. The magnetically enriched loess fractions show a remarkable increase in the content of magnetite. The enhancement of non-magnetic Fe~(3+) and a decrease of Fe~(2+) mineral phases in the paleosol layer seem to be a consequence of the process of pedogenesis which also caused a dissolution of magnetic iron oxides by weathering. The increase of magnetite in the silt fraction suggests that the wind could have been the main carrier of magnetic minerals, causing the major differences in the magnetic parameters between loess and paleosols in the Argentine loess plateau.