Geochemistry of micas from the Finero spinel-lherzolite, Italian Alps

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Authors:Exley, R. A.; Sills, Jane D.; Smith, J. V.
Author Affiliations:Primary:
Univ. Chicago, Dep. Geophys. Sci., Chicago, IL 60637, United States
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 81(1), p.59-63. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1982
Note:In English. 28 refs.; illus. incl. 21 anal., 2 tables
Summary:The Finero lherzolite is distinct from the tectonically emplaced slices of mantle in the Ivrea zone because of its abundant coarse phlogopite. An average composition (from 19 microprobe analyses) is SiO2 39.9, TiO2 0.97, Al2O3 16.0, Cr2O3 1.16, FeO 2.73, MgO 24.5, NiO 0.16, BaO 0.31, Na2O 0.58, K2O 8.7, Rb2O 0.056, Cl 0.03, F 0.10 and is comparable with that of primary-textured micas from coarse garnet-lherzolite xenoliths from South Africa. The Finero micas are lower in both K/Rb and K/Ba than the primary or secondary micas from South Africa; their mean values for these ratios (K/Rb 110-220; K/Ba 15-39) are lower than for almost all bulk rocks, but fit well with the ranges (109-180; 12-49) for the high-K lavas of the Roman region. The chemistry of the Finero micas is consistent with the introduction of an alkaline phase into peridotite during or before emplacement of the Finero complex from the upper mantle into the crust; the alkaline phase is attributed tentatively to the uppermost mantle. [R.A.H.]
Subjects:Alkali metals; Alkaline earth metals; Barium; Cumulates; Electron probe data; Fabric; Fluorine; Gaseous phase; Geochemistry; Halogens; Igneous rocks; Kimberlite; Magmas; Mantle; Metals; Mica group; Peridotites; Phlogopite; Plutonic rocks; Potassium; Rubidium; Sheet silicates; Silicates; Spinel lherzolite; Titanium; Trace elements; Ultramafic composition; Ultramafics; Upper mantle; Alps; Europe; Italy; Ivrea-Verbano Zone; Piemonte Italy; Southern Europe
Coordinates:N460800 N460800 E0083200 E0083200
Abstract Numbers:83M/1546
Record ID:1985080256
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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