Where fast weathering creates thin regolith and slow weathering creates thick regolith

Auteur(s) et Affiliation(s)

BAZILEVSKAYA, E.

Earth and Environmental Systems Inst., State Univ., Penn Hills, Etats-Unis

LEBEDEVA, M.

Earth and Environmental Systems Inst., State Univ., Penn Hills, Etats-Unis

PAVICH, M.

US Geological Survey, Eastern Geology and Paleoclimate Science Center, Reston, Etats-Unis

ROTHER, G.

Geochemistry and Interfacial Sciences Group, Chemical Sciences Div., National Lab., Oak Ridge, Etats-Unis

PARKINSON, D.Y.

Advanced Light Source, Lawrence Berkeley National Lab., Berkeley, Etats-Unis

COLE, D.

School of Earth Sciences, Ohio State Univ., Columbus, Etats-Unis

BRANTLEY, S.L.

Earth and Environmental Systems Inst., State Univ., Penn Hills, Etats-Unis

Description :
Here, the AA. investigate what controls the depth of regolith formed on ridges of 2 rock compositions with similar initial porosities in Virginia (USA). A priori, they predicted that the regolith on diabase would be thicker than on granite because the dominant mineral (feldspar) in the diabase weathers faster than its granitic counterpart. However, weathering advanced 20x deeper into the granite than the diabase. This is attributed mainly to connected micron-sized pores, microfractures formed around oxidizing biotite at 20 m depth, and the lower iron (Fe) content in the felsic rock. Such porosity allows pervasive advection and deep oxidation in the granite. These observations may explain why regolith worldwide is thicker on felsic compared to mafic rock under similar conditions. To understand regolith formation will require better understanding of such deep oxidation reactions and how they impact fluid flow during weathering.

Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2013, vol. 38, n°. 8, p. 847-858, nombre de pages : 12, Références bibliographiques : 2 p.

Date :
2013

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley

Langue :
Anglais