Field Perception of the Boundary Between Soil and Saprolite by Pedologists and its Differentiation Using Mathematical Models

Rare earth elements in gneiss regoliths in southern Minas Gerais, Brazil

“…Since interpretation of the distribution pattern of chemical elements throughout the regolith profile is particularly complex in rocks with heterogeneous structure, such as gneiss (Santos et al, 2019b), the present study adds to previous work done in the northeast of Brazil (Silva et al, 2001;Santos et al, 2019a) by characterizing REE distributions along three regolith profiles with the contrasting content of mafic minerals, namely, leuco-, meso-and melanocratic gneisses. The Passos, MG region offers a unique opportunity to investigate this set of regolith profiles weathered under similar conditions.…”

“…The soil-saprolite interface is crucial as a nutrient source for organisms, filtration of water, as well as the boundary between the dominance of weathering and pedogenic processes (Santos et al, 2017(Santos et al, , 2018b. In the field, the morphological distinction between soil and saprolite is not always clear, particularly in profiles developed from metamorphic, banded rocks (Santos et al, 2019b). The superimposition of parent rock heterogeneity and differentiation by weathering and pedogenetic processes imposes an extra difficulty on interpreting contrasting distributions of elements throughout the profile, not to mention the cases in which alloctonous material was added (Price and Velbel, 2003).…”