Mineralogical analysis as a means for distinguishing levels in a red soil chronosequence

• Published in: Communications in soil science and plant analysis Vol. 30; no. 13/14; pp. 1885 - 1896
• Main Authors: Vidal, M, Sanchez-Carpintero, I, Pinilla, A, Roquero, C, Lopez, A
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.01.1999; Taylor & Francis
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; brown soils; chronosequences; Earth sciences; Earth, ocean, space; Exact sciences and technology; fersiallitic soils; fluvioglacial soils; Fundamental and applied biological sciences. Psychology; Geochronology; Isotope geochemistry. Geochronology; mineral content; mineralogy; red soils; Soil science; soil separates; Soil surveys, classification and mapping; Soil surveys, classification and mapping, soil genesis; soil types; Spain; Spain; Pyrenees; France; Europe; Red soils; Mineralogical analysis; Mountain; Alluvial soil; Grade (ground level); Brown soil; Differentiation; Glacial geomorphology
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1080/00103629909370339

Three red soils and a brown soil developed on the three distinct levels of the fluviglacial terraces in the interfluvial area between the beds of the rivers Aragon and Aragon Subordan (Pyrenean range, France-Spain) were studied. This terrace system features ubiquitous red soil topping the upper 60 m terrace and brown soil on the intermediate (20 m) and lower terrace (2-3 m). However, the most salient feature of the studied area, an explanation for which was sought in this work, is the presence of red soils in the two sub-levels that form the 20 m terrace. For this purpose, and also with a view to characterizing the soils, material from the different levels studied was subject to textural analysis using three different dispersal methods (water, sodium hexametaphosphate, and previous removal of iron oxides). In this way, the clay/silt ratio and naturally dispersed clay (NDClay) were determined (the latter as the clay-H2O/clay-hexam ratio). The heavy and light fractions of sand were examined under a petrographic microscope and a scanning electron microscope (SEM) and the results were subjected to an analysis of variance. The interpretation of these results, in addition to the presence of pseudomorphic pyrites and other iron forms, and on the interpretation of analytical data, the red soils in the two sub-levels of the 20 m terrace were transported from a neighboring zone.