Petrography and mineralogy of oceanic peridotites and gabbros; some comparisons with ophiolite examples

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Authors:Hebert, Réjean
Author Affiliations:Primary:
Univ. Bretagne Occidentale, lab. océanol. géodynam., Brest, France
Volume Title:Ophiolites and actualism; Proceedings of the meeting
Volume Authors:Bortolotti, V., editor
Source:Ofioliti, 7(2-3), p.299-324; Ophiolites and actualism; meeting, Florence, Italy, Dec. 18-19, 1981, edited by V. Bortolotti. Publisher: Pitagora Editrice, Bologna, Italy. ISSN: 0391-2612
Publication Date:1982
Note:In English. 4 p. refs.; illus. incl. 20 anal., 3 tables, sketch map, block diag.
Summary:A selection of plutonic rocks sampled in transform faults on oceanic ridges and drilled in the oceanic crust are petrologically investigated to provide new data on the deep parts of the ocean crust and underlying upper mantle. Tectonites and cumulates are distinguished both on a structural and textural basis and on chemical mineralogy. Primary or slightly fractionated liquids evolved during magmatic fractionation, leaving cumulate rocks in which the cumulate minerals are olivine + or - chromite, plagioclase and clinopyroxene; the same model applies to extruded basalts. The chemistry of early fractionated cumulates gives an indication of the various conditions under which the magma fractionated. Similar variations should occur in ophiolite complexes derived from magmatic processes at spreading axes. The thermodynamic conditions should be re-evaluated, before geotectonic environments can be specified. [C.N.]
Subjects:Chain silicates; Crust; Feldspar group; Framework silicates; Gabbros; IGCP; Igneous rocks; Minor elements; Nesosilicates; Oceanic crust; Olivine; Olivine group; Ophiolite; Orthosilicates; Oxides; Paragenesis; Peridotites; Petrology; Phase equilibria; Plagioclase; Plate tectonics; Plutonic rocks; Pyroxene group; Sampling; Silicates; Spinel; Ultramafics; Pacific Ocean
Abstract Numbers:87M/5019
Record ID:1985081312
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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