Tectonic settings of the Plio–Quaternary volcanism in Iran from multidimensional and multielement solutions.

Geochemical data for 435 samples of the Pliocene to Quaternary (P–Q) volcanic rocks from Iran, distributed mostly along a NW–SE trending belt, were compiled from 28 papers (12 written in Persian). Until now, the rock nomenclature employed has been inconsistent with the recommendations of the International Union of Geological Sciences (IUGS). Moreover, older bivariate and ternary tectonic discrimination diagrams and only traditional qualitative approaches using Nb and Ta anomalies, have been used to understand the origin and evolution of the P–Q magmas. The P–Q magma and rock types were classified by strictly following the IUGS recommendations. Two geochemometric multidimensional models based on 10 and 16 elements, along with two decision procedures, capable of discriminating 29 fine tectonic settings, were used to document the existence of six tectonic settings in Iran during the P–Q. The rare earth elements indicated that the evolved intermediate and silicic rocks had a significant crustal component in their origin. The quantification of Nb and Ta anomalies in multielement diagrams was used to support the tectonic inferences from the multidimensional geochemometric models. [ABSTRACT FROM AUTHOR]