Neogene calc-alkaline extrusive and intrusive rocks of the karalar-yesiller area

The Karalar-Ye?iller area lies on the estern flank of the Kazda (bar g) i massif in northwestern Anatolia (Asiatic Turkey), and includes about 600 square kilometers, of which approximately 80% is covered by rhyodacite-quartz latite extrusive rocks, and a comagmatic granodiorite-quartz monzonite batholith, and stocks, all of middle Miocene age. Extrusive rocks consist chiefly of rhyodacite lava flows of the Hallaçlar Formation and quartz latite-rhyodacite ash-flow tuff, lava, and mudflow deposits of the overlying Dede Tepe Formation. These volcanic rocks lie on a basement composed, in asceding stratigraphic order, of: 1) pre-Permian Kalabak sequence, 2) Upper Triassic Halilar Formation, 3) post-Upper Triassic Ba (bar g) burun Formation, and 4) allochthons of middle Permian: and Upper Jurassic limestone. Intrusion of a granodiorite-quartz monzonite batholith during the middle Miocene was accompanied or shortly followed by extensive alteration and base metal mineralization of the Hallaçlar and older rocks. Intrusion of six rhyodacitequartz latite stocks followed the main phase of hydrothermal alteration. At least one of these stocks may have contributed material to the Dede Tepe Formation of middle Miocene age. Field relations, petrologic, and geochemical data as well as radiometric age dates suggest that the intrusive and extrusive rocks are comagmatic. Parent magma is probably derived from partial melting of subducted oceanic crust and accompanying oceanic sediments. Geologic relations locally indicate assimilation of sialic crust by the grandiorite-quartz monzonite batholith.