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Chemical composition and petrogenetic implications of apatites from some ultra-alkaline Italian rocks

Francesco Stoppa and Yu Liu
Chemical composition and petrogenetic implications of apatites from some ultra-alkaline Italian rocks
European Journal of Mineralogy (April 1995) 7 (2): 391-402

Abstract

The chemical compositions of apatites from some Italian late Pleistocene ultra-alkaline rocks were determined and compared with those from other ultra-alkaline suites, using principal component analysis. Three genetic groups were distinguished by means of the principal components diagram and a tetrahedra substitution index (TSI = 100 (super *) (Si + S + C)/P atom/apfu). Group I is made up of apatites from the ijolite-soevite association, with high contents of P, Sr, REE and considerable F (TSI = 1.6-6.8); group II samples are apatites from fine-grained extrusive calcite carbonatites with high C, Si, OH, low S and a dominant substitution of C and Si for P (TSI = 7.9-48.5); group III corresponds with apatites from alkaline rocks with high S, F and low C and OH contents and a dominant substitution of S and Si for P (TSI = 2.9-14.0). The apatite geochemistry suggests that an ijolite-soevite magma existed as a single parent system over a relatively large range of P-T-X conditions. The major geochemical differences between the apatites from extrusive calcite carbonatites and alkaline rocks could well reflect separation of the ijolite-soevite magma into silicate and carbonate liquids under sub-volcanic or extrusive conditions.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 2
Title: Chemical composition and petrogenetic implications of apatites from some ultra-alkaline Italian rocks
Affiliation: Universita di Perugia, Dipartimento di Scienze della Terra, Perugia, Italy
Pages: 391-402
Published: 199504
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 41
Accession Number: 1995-027341
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 plate, 3 tables, sketch map
N40°00'00" - N43°00'00", E12°00'00" - E16°00'00"
Secondary Affiliation: Wuhan Institute of Chemical Technology, CHN, China
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199510
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