Mössbauer and magnetic studies of parent material from Argentine pampas soils

J. C. BIDEGAIN; A. A. BARTEL; F. R. SIVES; R. C. MERCADER

HYPERFINE INTERACTIONS

Springer

Lugar: Netherlands; Año: 2007

0304-3843

In order to establish a correlation between the different types of soils using hyperfine and magnetic parameters as climatic and environmental proxies, we have studied the differentiation of soil developed around 38.5º south latitude, in the central Pampas of Argentina, by means of Mössbauer spectroscopy and environmental magnetism. The soils transect (climosequence) investigated stretches from the drier west (around 64° W) to the more humid east (at around 59° W) in the Buenos Aires Province, covering a distance of 600 km. The soils studied developed during recent Holocene geologic times in a landscape characterized by small relict plateaus, slopes and depressions, dunes and prairies. The parent material consists of eolian sandy silts overlying calcrete layers. The low mean annual precipitation in the western parts of the region gives rise to soils without B-horizons, which limits the agricultural use of land. The preliminary results show an increase of the paramagnetic Fe3+ relative concentration from west to east in the soils investigated. Magnetite is probably mainly responsible for the observed enhancement in the susceptibility values. The magnetic response of the parent material is similar to that of the loess part of the previously investigated loess-paleosol sequences of the Argentine loess plateau.