On the unreliability of silica and total alkali weight percentages as main classification parameters in petrology

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Authors:Stefanova, M. T.
Author Affiliations:Primary:
Univ. Sofia, Dep. Ore Deposits Geochem., Sofia, Bulgaria
Volume Title:Doklady Bolgarskoy Akademiya Nauk
Source:Doklady Bolgarskoy Akademiya Nauk, 38(10), p.1347-1349. Publisher: Bulgarska Akademiya na Naukite, Sofia, Bulgaria. ISSN: 0366-8681
Publication Date:1985
Note:In English. 2 refs.
Summary:The paper discusses certain aspects of the SiO2-Na2O + K2O classification diagram proposed by the petrological commission of the Petrographic Committee at the Academy of Sciences of the USSR, namely that it does not provide the possibility of determining the potential mineral composition of igneous rocks (the presence of quartz or foids, melanocratic degree, alkaline content of femic minerals); it does not consider the heteromorphic varieties of rocks of the same chemical composition. The classification of igneous rocks requires additional parameters. It is pointed out that the SiO2-Na2O + K2O diagram can be successfully applied in other fields of petrology - formational analysis, comparative studies on igneous series, etc. [R.A.]
Subjects:Classification; Crystalline rocks; Petrology; Silica
Abstract Numbers:88M/1225
Record ID:1987061578
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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