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GEOREF RECORD

Crystal chemistry of biotites from mafic enclaves in the Warburton granodiorite, Lachlan fold belt (Australia)

Maria Franca Brigatti, Cristina Lugli, Luciano Poppi and Marlina A. Elburg
Crystal chemistry of biotites from mafic enclaves in the Warburton granodiorite, Lachlan fold belt (Australia)
European Journal of Mineralogy (October 1998) 10 (5): 855-864

Abstract

The compositions of biotites from the host granodiorite and mafic microgranitic enclaves are discussed. The biotites have Fe/(Fe + Mg) ratios of 0.47-0.54; their contents of Ba and Ti are higher in the host granodiorite than in the enclaves. The Al [] Si substitution, greater than the ideal value, is taken to suggest the presence of exchange vectors involving octahedral, tetrahedral and interlayer substitutions. Crystal structure refinements display a nearly disordered cation distribution and quite regular polyhedra. All crystals analysed show a similar electron count for M1 and M2 octahedral sites, with mean bond lengths indicating the normal cation ordering scheme with M1 > M2. Equilibration did not reach completion, and the distinction in both mineralogy and isotopic composition between some enclaves and the host granodiorite are preserved; the disordered pattern of cation distribution may indicate rapid cooling.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 10
Serial Issue: 5
Title: Crystal chemistry of biotites from mafic enclaves in the Warburton granodiorite, Lachlan fold belt (Australia)
Affiliation: University of Modena, Department of Earth Sciences, Modena, Italy
Pages: 855-864
Published: 199810
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 37
Accession Number: 1998-070404
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
S42°00'00" - S30°00'00", E143°00'00" - E150°15'00"
Secondary Affiliation: University of Adelaide, AUS, Australia
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199824
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