Une nouvelle méthode pour la paléopodologie du Pliocène et du Villafranchien des Pyrénées centrales : l'étude des galets de quartzite à cortex d'altération

Abstract

It is shown that each weathered corona surrounded quartzite pebbles and some characteristics of the matrix can be regarded as the result of the same pedogenesis. Consequently each individualized pedological evolution, can be jointly studied on the matrix (classical pedological method) and on the cortex which presents two peculiar advantages : 1. individualization and relative localization in the course of time, of the great weathering periods ; the former are responsible for the cortex of the nearest of the heart of the pebble, the later for the peripherie coronas. 2. Characterization of each pedogenesis, thanks to the possible establishment of geochimical balances. This method applied to the pedology of the Pliocene and Pyrenean Villafranchian shows that two main evolutions have succeeded each other : the first one being of ferrallitic type and the other one of podzolic type.