The mineralogy of peraluminous granites; a review

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Authors:Clarke, D. B.
Author Affiliations:Primary:
Dalhousie Univ., Dep. Geol., Halifax, NS, Canada
Volume Title:Peraluminous granites
Volume Authors:Clarke, D. B., editor
Source:The Canadian Mineralogist, Vol.19(Part 1), p.3-17; Joint annual meeting of the Geological Association of Canada and the Mineralogical Association of Canada, Halifax, NS, Canada, May 19, 1980, edited by D. B. Clarke. Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada. ISSN: 0008-4476
Publication Date:1981
Note:In English with French summary. 71 refs.; illus. incl. 3 tables
Summary:Peraluminous granites are defined as those in which the ratio (mol.% proportions) Al2O3(CaO + Na2O + K2O) (=A/CNK) > 1. They consist of quartz + two feldspars + one or more characteristics minerals such as biotite, muscovite, garnet, cordierite, aluminosilicates, mullite, topaz, tourmaline, spinel and corundum. The occurrence of the minerals is controlled by factors of T, P, P(fluid)/P(total), and compositional variables such as fO2, fCO2, fHCl, fHF, SIGMA (MgO + FeO), MgO/FeO and minor element (B, Be, Mn, Li, Cs) content. Interpretation of mineral textures plays an important role in ascribing a mode of origin to the various minerals. A genetic classification for these minerals is proposed as follows: 1) exogenic: (a) restite and (b) xenocrysts from high-level country rocks; and 2) endogenic: (a) crystallization from silicate melt with A/CNK > 1, (b) crystallization from water-saturated, alkali-depleted silicate melt with A/CNK >> 1, (c) metasomatic replacement of silicate rock by vapour phase and (d) crystallization directly from aqueous fluid. Rocks formed by processes in categories 1(a), 1(b) and 2(a) are termed 'normal peraluminous' because they involve only melt compositions that can be reached by silicate melt-crystal equilibria. Those in categories 2(b), 2(c) and 2(d) are termed 'hyperaluminous' because they represent melt or whole-rock compositions with A/CNK >> 1 that result from the interaction of fluids with silicate melts or solid rocks. [S.A.K.]
Subjects:Aluminum; Genesis; Granites; Igneous rocks; Inclusions; Melts; Metals; Mineral composition; Plutonic rocks; Xenoliths; Abundance; Peraluminous granite
Abstract Numbers:86M/0925
Record ID:1982014422
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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