Comparative study of the classification of plutonic and volcanic rocks using the normative Q' (F')-ANOR and chemical SiO2-100·CaO/(CaO+K2O) diagrams
To obtain a classification of igneous rocks, compatible with the QAPF classification, in the absence of modal analyses, a chemical diagram using the same discriminating elements as the Q'(F')-ANOR normative diagram has been proposed. These elements, Si, Ca and K, are essential constituents o...
| Autores: | , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2019 |
| País: | España |
| Recursos: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositório: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/172888 |
| Acesso em linha: | https://hdl.handle.net/2445/172888 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Petrologia Roques ígnies Roques volcàniques Roques plutòniques Classificació Petrology Igneous rocks Volcanic rocks Plutonic rocks Classification |
| Resumo: | To obtain a classification of igneous rocks, compatible with the QAPF classification, in the absence of modal analyses, a chemical diagram using the same discriminating elements as the Q'(F')-ANOR normative diagram has been proposed. These elements, Si, Ca and K, are essential constituents of quartz, feldspars and feldspathoids. The different proportions between these minerals are the basis of the QAPF modal classification but also those of the normative classification Q'(F')-ANOR. The chemical diagram SiO2100·CaO/(CaO+K2O) uses these same elements but with the important difference that they are treated as independent variables. This characteristic allows igneous rocks to be classified with a nomenclature equivalent to that obtained by modal analyses, using only Si, Ca and K analytical data. The plotting of a set of representative plutonic and volcanic rocks reveals a remarkable concordance between both diagrams. However, some discrepancies and overlaps occur in the subsaturated fields due to the inability of the method to determine whether the lower silica content is due to the presence of olivine or feldspathoids. The samples selected belong to igneous series from diverse geotectonic areas , thus helping to evaluate the results in a global context. |
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