Contributions to Mineralogy and Petrology

, Volume 57, Issue 3, pp 297–303 | Cite as

K-Ar Radiometric Age Determinations of White Micas from the Piemont Zone, French-Italian Western Alps

  • Michel Delaloye
  • Jacqueline Desmons


K - Ar radiometric data are presented suggesting a different metamorphic history for both parts of the Piemont zone in the Western Alps: the Combin zone to the west, considered to have escaped the late Cretaceous metamorphic event, and the Zermatt-Saas zone to the east, where ophiolites predominate, and which has been affected by a first metamorphism during late Cretaceous.

Paragonite lenses within serpentinite give an isotopic ratio dating a serpentinization phase, or representing mixed ages. Late Cretaceous ages are found in the Zermatt-Saas zone and in the melange areas. The Combin zone gives only Eocene-Oligocene ages, as well as that part of the Zermatt-Saas zone that is closer to the Lepontine thermal high (dated as 38 m.y.). No late Oligocene-early Miocene ages (as previously obtained on Na-amphiboles) have been found among the investigated micas.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.



The support of the “Fonds national suisse pour la recherche scientifique” is gratefully acknowledged. Thanks are due to Dr. J.C Hunziker for critical reading.


  1. Aumento, F., Loubat, H.: The mid-Atlantic ridge near 45° N. XVI: Serpentinized ultramafic intrusions. Canad. J. Earth Sci. 8, 631–663 (1971)CrossRefGoogle Scholar
  2. Bearth, P.: Die Ophiolithe der Zone von Zermatt-Saas Fee. Beitr. geol. Karte Schweiz n.F. 132, 130p (1967)Google Scholar
  3. Bearth, P.: Zur Gliederung und Metamorphose der Ophiolithe der Westalpen. Schweiz. Mineral. Petrog. Mitt. 54, 385–397 (1974)Google Scholar
  4. Bertrand, J.: Etude pétrographique des ophiolites et des granites du Flysch des Gêts (Haute-Savoie, France). Arch. Sci. (Geneva) 23, 279–542 (1971)Google Scholar
  5. Bertrand, J., Delaloye, M.: Datation par la méthode K — Ar de diverses ophiolites du Flysch des Gêts (Haute-Savoie, France). Eclogae Geol. Helv., in press (1976)Google Scholar
  6. Bocquet (Desmons), J.: Etudes minéralogiques et pétrologiques sur les métamorphismes d’âge alpin dans les Alpes françaises. Thèse, Grenoble, 489 p. (1974)Google Scholar
  7. Bocquet (Desmons), J., Delaloye, M., Hunziker, J. C., Krummenacher, D.: K — Ar and Rb — Sr dating of blue amphiboles, micas and associated minerals from the Western Alps. Contrib. Mineral. Petrol. 47, 7–26 (1974)CrossRefGoogle Scholar
  8. Cipriani, C., Sassi, F. P., Viterbo-Bassani, C.: La composizione delle miche chiare in rapporto con le costanti reticolari e col grado metamorfico. Rend. Soc. Ital. Mineral. Petrol. 24, 153–187 (1968)Google Scholar
  9. Coleman, R. G.: The Colebrooke Schist of Southwestern Oregon and its relation to the tectonic evolution of the region. Geol. Surv. Bull. 1339, 61 p. (1972)Google Scholar
  10. Coleman, R. G., Lanphere, M.A.: Distribution and age of high-grade blueschists, associated eclogites, and amphibolites from Oregon and California. Geol. Soc. Amer. Bull. 82, 2397–2412 (1971)CrossRefGoogle Scholar
  11. Dal Piaz, G. V.: Alcune considerazioni sulla genesi delle ofioliti piemontesi e dei giacimenti ad esse associati. Boll. Assoc. Miner. Subalpina 8, 24 p. (1971)Google Scholar
  12. Dal Piaz, G. V.: Le métamorphisme de haute pression et basse température dans l’évolution structurale du bassin ophiolitique alpino-apenninique (1ère partie: considérations paléogéographiques). Boll. Soc. Geol. Ital. 93, 437–468 (1974)Google Scholar
  13. Delaloye, M., Wagner, J.J.: Potassium-Argon dating: an automatic equipment with digital output for computer processing. C.R. Soc. Phys. Hist. Nat. Geneva 9, 66–74 (1974)Google Scholar
  14. Desmons, J.: Mineralogical and petrological investigations of Alpine metamorphism in the internal French Western Alps. In preparationGoogle Scholar
  15. Frey, M., Hunziker, J. C., Frank, W., Bocquet (Desmons), L, Dal Piaz, G.V., Jäger, E., Niggli, E.: Alpine metamorphism of the Alps. A review. Schweiz. Mineral. Petrog. Mitt. 54, 247–290 (1974)Google Scholar
  16. Gianelli, G., Principi, G.: Studies on mafic and ultramafic rocks. 4.-Breccias of the ophiolitic suite in the Monte Bocco area (Ligurian Apennine). Boll. Soc. Geol. Ital. 93, 277–308 (1974)Google Scholar
  17. Honnorez, J., Kirst, P.: Petrology of rodingites from the equatorial Mid-Atlantic fracture zones and their geotectonic significance. Contrib. Mineral. Petrol. 49, 233–257 (1975)CrossRefGoogle Scholar
  18. Hunziker, J. C.: Rb — Sr and K — Ar age determination and the Alpine tectonic history of the Western Alps. Mem. Ist. Geol. Miner. Univ. Padova 31, 55 p. (1974)Google Scholar
  19. Iishi, K., Saito, M.: Synthesis of antigorite. Amer. Mineral. 58, 915–919 (1973)Google Scholar
  20. Johannes, W.: An experimental investigation of the system MgO —SiO2 —H2O-CO2. Am. J. Sci. 267, 1083–1104 (1969)CrossRefGoogle Scholar
  21. Purdy, J.W., Jäger, E.: K-Ar ages on rock-forming minerals from the Central Alps. Mem. Ist. Geol. Mineral. Univ. Padova, 30 (in press)Google Scholar
  22. Pusztaszeri, L.: Etude pétrographique du massif du Chenaillet (Hautes-Alpes, France). Schweiz. Mineral. Petrog. Mitt. 49, 425–466 (1969)Google Scholar
  23. Spooner, E.T. C., Fyfe, W.S.: Sub-sea-floor metamorphism, heat and mass transfer. Contrib. Mineral. Petrol. 42, 287–304 (1973)CrossRefGoogle Scholar
  24. Wenner, D. B., Taylor, H. P., Jr.: Temperatures of serpentinization of ultramafic rocks based on O18/O16 fractionation between coexisting serpentine and magnetite. Contrib. Mineral. Petrol. 32, 165–185 (1971)CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • Michel Delaloye
    • 1
  • Jacqueline Desmons
    • 2
  1. 1.Département de Minéralogie de l’Université de GenèveGenève 4Switzerland
  2. 2.Institut DolomieuLaboratoire de Géologie AlpineGrenoble CedexFrance

Personalised recommendations