Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-07T07:24:53.523Z Has data issue: false hasContentIssue false
  • English
  • Français

Hydrothermal and Supergene Alterations in the Granitic Cupola of Montebras, Creuse, France

Published online by Cambridge University Press:  02 April 2024

P. Dudoignon ,
D. Beaufort  and
A. Meunier
P. Dudoignon
Affiliation:
Université de Poitiers, U.F.R. Sciences, Laboratoire de pétrologie des altérations hydrothermales, E.R.A. 220 du C.N.R.S., 40, Avenue du recteur Pineau, 86022 Poitiers Cedex, France
D. Beaufort
Affiliation:
Université de Poitiers, U.F.R. Sciences, Laboratoire de pétrologie des altérations hydrothermales, E.R.A. 220 du C.N.R.S., 40, Avenue du recteur Pineau, 86022 Poitiers Cedex, France
A. Meunier
Affiliation:
Université de Poitiers, U.F.R. Sciences, Laboratoire de pétrologie des altérations hydrothermales, E.R.A. 220 du C.N.R.S., 40, Avenue du recteur Pineau, 86022 Poitiers Cedex, France
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A mineralogical investigation of the highly kaolinized Chanon granite and albite-muscovite granite of the Montebras cupola, Creuse, France, indicates that the magmatic stage was followed by two hydrothermal events related to successive cooling stages and by late weathering. The hydrothermal alteration was accompanied first by greisen formation and then a broad kaolinization process, which pervasively affected the granitic bodies. In the Chanon granite, the greisens are characterized by a trilithionite-lepidolite-quartz-tourmaline assemblage and are surrounded by concentric alteration zones. From the greisen to the fresh granite three zones were distinguished: (1) a zone characterized by secondary brown biotite (<400°C), (2) a zone characterized by secondary green biotite and phengite (300–350°C), and (3) a zone characterized by the presence of corrensite (180°–200°C) located around greisen veinlets. In the albite-muscovite granite the greisen is composed of lepidolite and quartz. This mineral assemblage was followed locally by Li-tosudite crystallization. During the second hydrothermal event (<100°C) an assemblage of kaolinite, mixed-layer illite/smectite (I/S), and illite formed pervasively and in crack fillings; the smectite layers of the US are potassic. Weathering produced Fe oxide and kaolinite. This kind of alteration developed mainly in the overlying Chanon granite. Here, Ca-Mg-montmorillonite formed in subvertical cracks, which transect the two granitic bodies, and hydrothermal I/S was obliterated by Ca-Mg-montmorillonite.

The hydrothermal parageneses were apparently controlled by magmatic albitization and the bulk chemistry of the two granitic bodies. The albitization, the formation of large micaceous greisens, and the successive recrystallizations of biotite (which was the most susceptible phase to alteration) provide information on the temperature range and chemical mobility during successive cooling stages. Si and Mg activities increased as the temperature of alteration decreased, and secondary Mg-biotite and Mg-phengite crystallized as long as the K activity was sufficient. The crystallizations of secondary biotite and phengite were followed by the crystallization of I/S during stages of low K activity. Secondary hydrothermal phases in the Chanon granite contain substantial Fe and Mg. Secondary hydrothermal phases in the albite-muscovite granite contain only small amounts of Fe and Mg, suggesting a lack of chemical exchange between the enclosing Chanon granite and the albite-muscovite granite, which is depleted in Fe-Mg-rich primary phases, such as biotite.

Keywords

BiotiteChloriteCorrensiteGraniteGreisenHydrothermalKaolinPetrographyWeathering
Type
Research Article
Information
Clays and Clay Minerals , Volume 36 , Issue 6 , December 1988 , pp. 505 - 520
Copyright
Copyright © 1988, The Clay Minerals Society

References

Aubert, G. (1969) Les coupoles granitiques de Montebras et d’Echassières (Massif Central français) et la genèse de leur minéralisation étain-lithium-tungstène-bérylium: Mém. BRGM 46, 354 pp.Google Scholar
Beane, R. E., 1974 Biotite stability in the porphyry copper environment Econ. Geol. 69 241 – 256.CrossRefGoogle Scholar
Beaufort, D. (1981) Etude pétrographique des altérations hydrothermales superposées dans le porphyre cuprifère de Sibert (Rhône, France). Influence des microsystèmes géochimiques dans la différenciation des micas blancs et des phases trioctaédriques: Thèse 3e cycle, Univ. Poitiers, Poitiers, France, 147 pp.Google Scholar
Beaufort, D., 1984 Aninterstratified illite/smectitemineral from the hydrothermal deposit in Sibert, Rhône, France Clays & Clay Minerals 32 154 – 156.CrossRefGoogle Scholar
Beaufort, D. and Meunier, A., 1983a A petrographic study of phyllic alteration superimposed on potassic alteration: The Sibert porphyry deposit (Rhône, France) Econ. Geol. 78 1514 – 1527.CrossRefGoogle Scholar
Beaufort, D. and Meunier, A., 1983b Petrographic characterization of an argillic hydrothermal alteration containing illite, K-rectorite, K-beidellite, kaolinite and carbonates in a cupromolybdenic porphyry at Sibert (Rhône, France) Bull. Minér. 106 533 – 551.Google Scholar
Beaufort, D., Dudoignon, P., Proust, D., Parneix, J. C. and Meunier, A., 1983 Microdrilling in thin section: A useful method for identification of clay minerals in situ Clay Miner. 18 219 – 222.CrossRefGoogle Scholar
Brindley, G. M. and Brown, G., 1980 Crystal Structures of Clay Minerals and their X-Ray Identification London Min-eralogical Society.CrossRefGoogle Scholar
Cathelineau, M. (1982) Les gisements d’uranium liés spatialement aux leucogranites Sud-armoricains et leur encaissant métamorphique: Relation et interaction entre les minéralisations et divers contextes géologiques et structuraux: Sci. de la Terre 42, 375 pp.Google Scholar
Charoy, B., 1975 Ploëmeur kaolin deposit: An example of hydrothermal alteration Petrology I 4 253 – 266.Google Scholar
Charoy, B. (1979) Définition et importance des phénomènes deutériques et des fluides associés dans les granites. Conséquences métallogéniques: Mém. BRGM 37, 364 pp.Google Scholar
Creach, M., Meunier, A. and Beaufort, D., 1986 Tosudite occurrence in the kaolinized granitic cupola of Montebras (Creuse, France) Clay Miner. 21 225 – 230.CrossRefGoogle Scholar
Dudoignon, P. (1983) Altérations hydrothermales et supergènes des granites. Etude des gisements de Montebras (Creuse), de Sourches deux-Sèvres) et des arènes granitiques (Massif de Parthenay): Thèse 3e cycle Univ. Poitiers, Poitiers, France, 120 pp.Google Scholar
Eberl, D. and Hower, J., 1977 The hydrothermal transformation of sodium and potassium smectite into mixed layer clay Clays & Clay Minerals 25 215 – 227.CrossRefGoogle Scholar
Exley, C. S., 1976 Observations on the formation of kaolinite in the St-Austell granite, Cornwall Clay Miner. 11 51 – 63.CrossRefGoogle Scholar
Foster, M. D., 1960 Interpretation of the compositions of lithium micas U.S. Geol. Surv. Prof. Pap. 354 115 – 146.Google Scholar
Fournier, R. O., 1967 The porphyry copper deposit exposed in the Liberty open pit-mine near Ely, Nevada, Part. II. The formation of hydrothermal alteration zones Econ. Geol. 62 207 – 227.CrossRefGoogle Scholar
Ichikawa, A. and Shimoda, S., 1976 Tosudite from the Hokuno mine, Hokuno, Gifu Prefecture, Japan Clays & Clay Minerals 24 142 – 148.CrossRefGoogle Scholar
Jacobs, D. C. and Parry, W. T., 1976 A comparison of the geochemistry of biotite from some Basin and Range stocks Econ. Geol. 71 1029 – 1035.CrossRefGoogle Scholar
Jacobs, D. C. and Parry, W. T., 1979 Geochemistry of biotite in the Santa Rita porphyry copper deposit, New Mexico Econ. Geol. 74 860 – 887.CrossRefGoogle Scholar
Konta, J. and Heller, L., 1969 Comparison of the proofs of hydrothermal and supergene kaolinization in two areas of Europe Proc. Int. Clay Conf., Tokyo, 1969, Vol. 1 Jerusalem Israel Univ. Press 281 – 290.Google Scholar
Kükne, R., Wasternack, J. and Schulze, C., 1972 Post-magmatische Metasomatose Evokontakt der Jüngeren post kinematischen Granite des Erzgebirges Geologie Dtsch. 21 494 – 520.Google Scholar
MacDowell, D. M. C. and Elders, W. A., 1980 Authigenetic layer silicate in borehole Elmore 1, Salton Sea geothermal field, California, U.S.A. Contrib. Mineral. Petrol. 74 293 – 310.CrossRefGoogle Scholar
Maksimović, Z. and Brindley, G. W., 1980 Hydrothermal alteration of a serpentine near Takovo, Yugoslavia, to chromium bearing illite/smectite, kaolinite, tosudite, and hal-loysite Clays & Clay Minerals 28 295 – 302.CrossRefGoogle Scholar
Matsuda, T. and Henmi, K., 1973 Hydrothermal behavior of the interstratified mineral from the mine of Ebara, Hyago Prefecture, Japan (an example of changes from randomly interstratified clay mineral to regular one) J. Clay Science Soc. Japan 13 87 – 94.Google Scholar
Meunier, A. (1980) Les mécanismes de l’altération des granites et le rôles des microsystèmes. Etude des arènes du massif granitique de Parthenay (Deux-Sèvres): Mém. Soc. Géol. Er. 140, 80 pp.Google Scholar
Meunier, A., 1982 Superposition de deux altérations hydrothermales dans la syénite monzonitique du Bac-de Montmeyre (sondage INAG 1, Massif Central, France) Bull. Minéral. 105 386 – 394.CrossRefGoogle Scholar
Meunier, A. and Velde, B., 1982 Phengitization, sericitization and potassium beidellite in a hydrothermally altered granite Clay Miner. 17 285 – 299.CrossRefGoogle Scholar
Monier, G. (1985) Cristallochimie des micas des leucogranites. Nouvelles données expérimentales et applications pé-trologiques: Thèse Doctorat ès sciences, Univ. Orléans, Orléans, France, 299 pp.Google Scholar
Munoz, J. L., 1968 Physical properties of synthetic lepid-olites Amer. Mineral. 56 1490 – 1512.Google Scholar
Munoz, J. L., 1971 Hydrothermal stability relations of synthetic lepidolite Amer. Mineral. 56 2069 – 2087.Google Scholar
Nicolas, J. and Rosen, A., 1966 Le massif des Colettes (Allier) et ses minéralisations Bull. Soc. Fran. Mineral. Crist. 7 126 – 128.Google Scholar
Nielsen, R. L., 1968 Hypogene texture and mineral zoning in a copper-bearing granodiorite porphyry stock, Santa Rita, New Mexico Econ. Geol. 63 37 – 50.CrossRefGoogle Scholar
Nishiyama, T., Shimoda, S., Shimosaka, K. and Kanaoka, S., 1975 Lithium-bearing tosudite Clays & Clay Minerals 23 337 – 342.CrossRefGoogle Scholar
Reynolds, R. C., Brindley, G. W. and Brown, G., 1980 Interstratified clay minerals Crystal Structure of Clay Minerals and their X-ray Identification London Mineralogical Society 249 – 303.CrossRefGoogle Scholar
Reynolds, R. C. and Hower, J., 1970 The nature of interlaying in mixed-layer illite-montmorillonite Clay & Clay Minerals 18 25 – 36.CrossRefGoogle Scholar
Rieder, M., 1971 Stability and physical properties of synthetic lithium-iron micas Amer. Mineral. 56 256 – 280.Google Scholar
Rieder, M., Huka, M., Kucerova, D., Minarik, L., Obermajor, J. and Povondra, P., 1970 Chemical composition and physical properties of lithium-iron micas from the Krusne Hory Mts. (Erzgebirge) Contrib. Mineral. Petrol. 27 131 – 158.CrossRefGoogle Scholar
Robert, J. L. and Volfinger, M., 1979 Etude expérimentale de lépidolites trioctaédriques hydroxylées Bull. Minéral. 102 21 – 25.CrossRefGoogle Scholar
Shimoda, S. (1975) X-Ray and I.R. studies of sudoite and tosudite: Contrib. Clays Min. in Honor Prof. Tushio Sudo, 92–96.Google Scholar
Sudo, T. and Shimoda, S., 1978 Clays and Clay Minerals of Japan Amsterdam Elsevier.Google Scholar
Velde, B., 1977 Clays and Clay Minerals in Natural and Synthetic Systems Amsterdam Elsevier.Google Scholar
Velde, B., 1984 Electron microprobe analysis of clay minerals Clay Miner. 19 243 – 247.CrossRefGoogle Scholar
Velde, B., 1985 Clay Minerals. A Physico-Chemical Explanation of their Occurrence Amsterdam Elsevier.Google Scholar