Oceanic carbonatites

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Authors:Le Bas, M. J.
Author Affiliations:Primary:
Univ. Leicester, Dep. Geol., Leicester, United Kingdom
Volume Title:Kimberlites; I, Kimberlites and related rocks
Volume Authors:Kornprobst, J., editor
Source:Vol.(11A), p.169-178; Third international kimberlite conference, Clermont-Ferrand, France, Sept., 1982, edited by J. Kornprobst. Publisher: Elsevier Sci. Publ., Amsterdam, Netherlands. ISBN: 0-444-42273-0
Publication Date:1984
Note:In English; illus. incl. 6 tables
Summary:The carbonatite-ijolite magmatic intrusive association occurs on oceanic volcanic islands as well as on the continents, and is relatively more abundant on the former than on the latter when only plutonic rocks are considered. Oceanic carbonatites are in most respects identical with continental carbonatites, but show some differences in trace-element geochemistry and the nature of the associated fenitization. They are richer in the incompatible elements and, besides showing an overall greater content of REE, show a markedly greater content of HREE. Whilst K-rich orthoclasites constitute the dominant fenites around carbonatites on the continents, the oceanic carbonatites show a much greater development of albitites, although some orthoclasites are present. The cause of the contrasting Na and K contents of the fenitizing fluids is not yet apparent, and the possibility of alkali exchange as the result of a saline hydrothermal circulation system set up within the oceanic volcanic islands must be considered. Such an exchange may also be related to the frequent secondary dolomitization observed in the oceanic carbonatites. [J.M.H.]
Subjects:Carbonatites; Geochemistry; Histograms; Igneous rocks; Ijolite; Intrusions; Metals; Petrology; Plutonic rocks; Rare earths; Statistical analysis; Trace elements; Africa; Atlantic Ocean; Atlantic Ocean Islands; Canary Islands; Cape Verde Islands
Abstract Numbers:85M/4655
Record ID:1984046695
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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