Nephelinitic and basanitic rocks

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Authors:Le Bas, M. J.
Author Affiliations:Primary:
Univ. Leicester, Dep. Geol., Leicester, United Kingdom
Volume Title:Journal of Petrology
Source:Journal of Petrology, 30(5), p.1299-1312. Publisher: Clarendon Press, Oxford, United Kingdom. ISSN: 0022-3530
Publication Date:1989
Note:In English. Submitted on behalf of the IUGS Subcommission on the Systematics of Igneous Rocks. 53 refs.; illus. incl. 6 tables
Summary:Basanites (which mineralogically should be characterized by an abundance of plagioclase and only minor feldspathoid) and nephelinitic rocks (which normally lack modal plagioclase but should contain nepheline) are not easily distinguished in the field, and both are commonly confused with basalts. A chemical distinction is desirable, particularly when no felsic minerals are apparent in the groundmass. A boundary at 20 wt.% CIPW normative ne best divides nephelinites from melanephelinites and basanites. Basanites are best distinguished from melanephelinites by a boundary at 5% CIPW normative ab. The melanephelinites so defined can be further divided into olivine melanephelinite and pyroxene melanephelinite. [R.A.H.]
Subjects:Basanite; Chemical composition; Classification; Composition; Igneous rocks; Mineral composition; Nephelinite; Volcanic rocks
Abstract Numbers:90M/3437
Record ID:1990018347
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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