Estudio de las propiedades magnéticas en las terrazas del río Tajo: implicaciones paleoambientales

Abstract

Soil profiles from 12 terraces of Plio-Pleistocene to Holocene age from the Tajo river in Central Spain were investigated on there rock magnetic properties. Systematic profiles were sampled in O. 1 m intervals from 24 fresh trenches of 2.5m depth. The soil profiles consist of an upper eluvial horizon (A, E), a intermediate illuvial horizon (B), and sometimes a lower horizon (C). Low and high frequency susceptibility (x), saturation IRM (SIRM), and anhysteretic remanent magnetization (ARM) measurements were performed out. The differences between the stable values of horizon B and the high values of the horizons A and E increase with the age of the soils. Comparison of the mean values of the B horizons for each terrace show low X values for the Holocene and the Late Pleistocene, a strong x increase during the Middle Pleistocene, and again low values for the Pliocene and Early Pleistocene. Magnetic parameters of soils show the palaeoenvironmental changes during this period of time.