RT Journal Article
T1 Una clasificación normativa de las rocas plutónicas y volcánicas mediante el diagrama 2Q-(or+ab)-4an-2F
T1 A normative classification of plutonic and volcanic rocks using the 2Q- (or+ab)- 4an-2F diagram
A1 Enrique Gisbert, Pere
AB Modal analyses provide a precise classification of the plutonicrocks, as demonstrated by the great acceptance of the QAPF diagram.However, the existence of isomorphic series in feldspars causes someindeterminations and discontinuities in the fields of classification. Consequently, distinct rocks overlap at the same point, as is the case of thegabbro and the diorite. In volcanic rocks, the accuracy of the determination decreases strongly and its classificationcan become a simpleapproximation, or even become impossible in the hyaline rocks. Anotherlogical drawback that derives from the different resolution is that someclassification fields are different in plutonic and volcanic rocks, so thereis no nomenclature equivalence for the same compositions. The normative diagram 2Q-(or+ab)-4an-2F proposed in this work allows todiscriminate clearly between rocks with plagioclases of different compositions as well as to compare plutonic and volcanic rocks using thesame parameters, independently of whether they are phaneritic oraphanitic rocks. As a result, two diagrams are obtained whose classification fields correspond exactly to the plutonic and volcanic rocks. Sincethe number of fields obtained is greater than those of the QAPF diagram, several new rock names are proposed, some of which may havean unlikely existence in nature
PB Sociedad Geológica de España
YR 2018
FD 2018
LK http://hdl.handle.net/10272/16739
UL http://hdl.handle.net/10272/16739
LA spa
DS Repositorio Institucional de la Universidad de Huelva
RD 14 jul 2026