Annales de la Société géologique de Belgique Annales de la Société géologique de Belgique -  Publications spéciales = special publications  Géologie des domaines cristallins - Centenaire de la Société géologique de Belgique, 1974 

Anorthosites and their environment

D. de Waard
Heroy Geology Laboratory, Syracuse University, Syracuse, New York 13210, U.S.A.
Jean-Clair Duchesne
Géologie, Pétrologie et Géochimie, Université de Liège, Sart-Tilman, Belgique.
Jean Michot
Laboratoire de Minéralogie et de Pétrologie, Université Libre de Bruxelles, Bruxelles, Belgique.

Abstract

This joint paper, written in honour of Professor Paul Michot, explores differences in interpretation of some well-studied anorthositic terrains which are geologically similar in many respects.

The Adirondack anorthosites and the Nain complex in Labrador are considered anorogenic plutons with long fractionation histories, giving rise to a great variety of associated rock types. It is concluded that anorthosite massifs are essentially anorogenic, and related in space and time to each other and to the rapakivi plutons of Fennoscandia (D. de W.).

The Rogaland complex of southern Norway, at the other hand, is considered a synorogenic pluton, which differentiated from a parental magma to some degree hybridized by crustal material. Here the conclusion is that anorthosites are emplaced at different times in the tectomagmatic cycle, and at various levels in the earth's crust (J. C. D. and J. M.).

A joint conclusion is that the parental magma must have had a monzogabbroic to granodioritic or monzonoritic to quartz-monzonoritic composition.

To cite this article

D. de Waard, Jean-Clair Duchesne & Jean Michot, «Anorthosites and their environment», Annales de la Société géologique de Belgique [En ligne], Publications spéciales = special publications, Géologie des domaines cristallins - Centenaire de la Société géologique de Belgique, 1974, 323-346 URL : https://popups.ulg.ac.be/0037-9395/index.php?id=3735.