The Dikili-Candarli Volcanics, Western Turkey: Magmatic Interactions as Recorded by Petrographic and Geochemical Features

Abstract

Located in the northwestern part of the Aegean region, Dikili- Candarli volcanic suite contains products representative for the western Anatolian Miocene volcanism. They can be divided into two main groups: the Dikili and the Candarli groups. The Dikili group is Early - Middle Miocene in age and consists mainly of pyroclastic rocks, andesitic- dacitic lavas, lava breccia, lahar flows and associated sedimentary rocks. The lavas contain disequilibrium phenocrysts assemblages. The Candarli group consists of Upper Miocene - Pliocene lava and sediment associations. The volcanic rocks consist mainly of rhyolitic domes and basaltic trachyandesite- basaltic andesite lavas erupted along the NW - SE- and NE - SW- trending fault systems; the faults controlled the development of the Candarli depression. Major- and trace- element chemistry indicates that the lavas are dominantly high- K, calc- alkaline, intermediate to acidic in composition. Chemical and textural characteristics of the minerals reveal that mixing was a common process in the generation of this magma. In particular, petrography, textural evidence and crystal chemistry of the phenocrysts together with variations in rock compositions indicate that basaltic- basaltic andesitic magma intruded dacite magma and is partially hybridized with it. New petrographic and geochemical data of Dikili-Candarli volcanics are closely similar to those of the active continental margin volcanism which are interpreted as mantle- derived magmas contaminated by crustal materials.