Turkish Journal of Earth Sciences (Turkish J. Earth Sci.), Vol. 16, 2007, pp. 493–522. Copyright ©TÜB‹TAK The Dikili-Çandarl› Volcanics, Western Turkey: Magmatic Interactions as Recorded by Petrographic and Geochemical Features ZEK‹YE KARACIK1, YÜCEL YILMAZ2 & JULIAN A. PEARCE3 1 ‹stanbul Technical University, Faculty of Mines, Department of Geology, Ayaza¤a, TR–34469 ‹stanbul, Turkey (E-mail:
[email protected]) 2 Kadir Has University, Cibali Merkez Kampüsü, Cibali, TR–34230 ‹stanbul, Turkey 3 Cardiff University, Department of Earth, Ocean and Planetary Science, Cardiff, UK Abstract: Located in the northwestern part of the Aegean region, Dikili-Çandarl› volcanic suite contains products representative for the western Anatolian Miocene volcanism. They can be divided into two main groups: the Dikili and the Çandarl› 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 Çandarl› 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 Çandarl› 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.