Clays and Clay Minerals, Vol. 54, No. 1, 87-100, 2006.
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Authors
Caillaud, J.
Proust, D.
Righi, D.
Issue Date
2006
Type
Article
Language
en_US
Keywords
Periodicals , Geology , Iron , Regolith , Serpentinite , Texture , Weathering
Alternative Title
Weathering Sequences of Rock-forming Minerals In A Serpentinite: Influence Of Microsystems On Clay Mineralogy
Abstract
Under closed geochemical conditions, the weathering of a serpentinite rock composed of serpentine (70-85%) and magnesian chlorite (10-15%) associated with magnetite and chromite leads to the complete replacement of serpentine and chlorite by 2:1 layer silicates and produces new Fe oxides. The serpentine minerals crystallize under different habits issued from the serpentinization processes: mesh and hourglass pseudomorphic textures were formed from olivine, and thin-bladed pseudomorphic textures from pyroxene and amphibole crystals. Serpentine veins crosscut the whole rock with locally non- pseudomorphic interpenetrating and interlocking serpentines. Specific weathering microsystem habits with specific clay mineral crystallizations originate from these different habits: a poorly aluminous saponite in thin-bladed textures, two Fe-rich montmorillonites in mesh and hourglass (MH) textures, and in veins (V) which differentiate on Al, Mg and Fe contents. Magnesian chlorites, isolated from serpentine by hand-picking under a stereomicroscope, are found to weather to trioctahedral vermiculite. Magnetite and chromite extracted from the bulk samples are replaced by newly formed Fe oxides, maghemite, goethite and hematite, which give way to specific Fe accumulation habits in the regolith zone of the weathering profile.
Description
gsccm-54-1-11-cai.pdf 1.50 MB PDF/A
Citation
Clays and Clay Minerals, Vol. 54, No. 1, 87-100, 2006.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society