Magnetic parameter analysis of a climosequence of soils in the southern pampean region, argentina

Abstract

Magnetic parameters of different soil types from Caleu–Caleu, La Pampa, Tres Arroyos, Buenos Aires province, Argentina show an increase in ferrimagnetic mineral concentrations in the solum. Titanomagnetites are major magnetic minerals in the soils. The distribution patterns of grain size dependent magnetic parameters, anhysteric susceptibility and frequency dependent susceptibility versus depth reflect changes to smaller grain sizes, especially single domain, in the upper soil horizons. This magnetic behavior is more evident in the humid than in the dry region. These soils represent a climosequence, where drier conditions are represented towards the west of the transect and were classified as Torripsamment and aridic Haplustoll types. Higher relative humidity conditions towards the east of the transect yield a development of Argiustolls and Argiudolls. The behavior of magnetic parameters appears to reflect the degree of pedogenesis reached in the area with a mean annual temperature around 14 ºC and a rainfall ranging between 400 to 800 mm/year. The data indicate a new magnetic pattern, opposite of that obtained in soils in the north of the Pampean prairie.