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Marine and supergene alteration processes in a chloritized amphibole-schist, Deux-Sevres, France

Published online by Cambridge University Press:  09 July 2018

D. Proust ,
P. Dudoignon ,
A. Bouchet  and
A. Meunier
D. Proust
Affiliation:
Laboratoire de Pétrologie de la Surface, Université de Poitiers, 86022 Poitiers Cédex
P. Dudoignon
Affiliation:
Laboratoire de Pétrologie des Altérations Hydrothermales, Université de Poitiers, 86022 Poitiers Cédex, France
A. Bouchet
Affiliation:
Laboratoire de Pétrologie des Altérations Hydrothermales, Université de Poitiers, 86022 Poitiers Cédex, France
A. Meunier
Affiliation:
Laboratoire de Pétrologie des Altérations Hydrothermales, Université de Poitiers, 86022 Poitiers Cédex, France
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Abstract

Mineralogical examination of a strongly chloritized amphibole-schist indicated that it had been subjected to two alteration episodes of different origin. Structural and petrographic evidence showed that the alteration processes operated per descensum from the bedrock surface down to shallow depth, thus eliminating any hydrothermal episode due to fluid ascension through deep fractures. The rock was first altered into interstratified chlorite-vermiculite minerals with potassic interlayers. These potassic clay minerals occur in an originally K-deficient rock and seem to have been generated by a marine alteration episode; this episode appears to be contemporaneous with the Cenomanian transgression which covered the amphibole-schist with sandy-clayey deposits. The potassic clay minerals were replaced during a later meteoric alteration episode by kaolinites, iron oxides, and smectites with Mg, Ca interlayer cations.

Type
Research Article
Information
Clay Minerals , Volume 22 , Issue 2 , June 1987 , pp. 129 - 143
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1987

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References

Bain, D.C. (1977) The weathering of chloritic minerals in some Scottish soils. J. Soil Sci. 211, 144–164.Google Scholar
Beaufort, D., Dudoignon, P., Proust, D., Parneix, J.C. & Meunier, A. (1983) Microdrilling in thin section: a useful method for the identification of clay minerals in situ. Clay Miner. 18, 219–222.Google Scholar
Cathelineau, M. (1982) Les gisements d'uranium liés spatialement aux leucogranites sud-armoricains et à leur encaissant métamorphique: relation et interaction entre les minéralisations et divers contextes géologiques et structuraux. Sci. Terre, Nancy, Mém 42, 375 pp.Google Scholar
Dudoignon, P. (1983) Altérations hydrothermales et supergénes des granites. Etude des gisements de Montebras (Creuse), de Sourches (Deux-Sèvres) et des arènes granitiques (Massif de Parthenay). Thèse 3e cycle, Univ. Poitiers, France, 117 pp.Google Scholar
Foster, M.D. (1962) Interpretation of the composition and a classification of the chlorites. U.S. Geol. Surv. Prof. Paper 414-A, 1–33.Google Scholar
Humphris, S.E., Thompson, R.N. & Marriner, G.F. (1979) The mineralogy and geochemistry of basalt weathering, Holes 417 A and 418 B. Initial Reports of the D.S.D.P 51-52-53 part 2, 1201–1217.Google Scholar
Ildefonse, Ph. (1978) Mécanismes de l'altération d'une roche gabbroïque du Massif du Pallet (Loire Atlantique). Thèse 3e cycle, Univ. Poitiers, France, 142 pp.Google Scholar
Ildefonse, Ph., Proust, D., Meunier, A. & Velde, B. (1979) Rôle des phénomènes de déstabilisation-recristallisation successifs dans 1-altération des roches cristallines au sein des micristystèmes chimiques. Sci. Sol-Bull. A.F.E.S. 2-3, 239–257.Google Scholar
Meunier, A. & Velde, B. (1982) Phengitization, sericitization and potassium beidellite in a hydrothermally altered granite. Clay Miner. 17, 285–299.CrossRefGoogle Scholar
Meunier, A., Velde, B., Dudoignon, P. & Beaufort, D. (1983) Identification of weathering and hydrothermal alteration in acidic rocks: petrography and mineralogy of clay minerals. Sci. Géol. Mém. 72, 93–99.Google Scholar
Mevel, C. (1979) Mineralogy and chemistry of secondary phases in low temperature altered basalts from D.S.D.P. Legs 51, 52, 53. Initial Reports of the D.S.D.P. 51-52-53 part 2, 1299–1312.Google Scholar
Proust, D. (1983) Mécanismes de l'altération supergène des roehes basiques. Etude des arènes d'orthoamphibolite du Limousin et de glaucophanite de l’Ile de Groix (Morbihan). Thèse Univ. Poitiers, France, 197 pp.Google Scholar
Rabenhorst, M.C., Fanning, D.S. & Foss, J.E. (1982) Regularly interstratified chlorite/vermiculite in soils over meta-igneous mafic rocks in Maryland. Clays Clay Miner. 30, 156–158.CrossRefGoogle Scholar
Ross, G. J., Wang, C., Ozkan, A.I. & Rees, H. W. (1982) Weathering of chlorite and mica in a New Brunswick podzol developed on till derived from chlorite-mica schist. Geoderma 27, 255–267.Google Scholar
Scarfe, C.M. & Smith, D.G.W. (1977) Secondary minerals in some basaltic rocks from D.S.D.P. Leg 37. Can. J. Earth Sci. 14, 903–910.Google Scholar
Steinberg, M. (1967) Contribution à l'étude des formations continentales du Poitou. Thèse Paris, France, 415 ppGoogle Scholar