Mechanism of emplacement and origin of the Ildır lava dome in the Karaburun Peninsula, western Anatolia (Turkey)

Abstract

The Karaburun Peninsula, which is considered to be a part of the Anatolide-Tauride Block, is situated between western Anatolia and the eastern part of the Aegean Sea, in a post-collisional extensional environment, and is located within the Izmir-Balıkesir Transfer Zone. The Paleozoic – Mesozoic basement rocks of the peninsula are cut and covered by Miocene volcanic successions, comprising mostly andesitic lavas and volcanoclastic deposits that interfinger with detrital lacustrine deposits. A NW-SE elongated andesitic exogenous composite lava dome structure (major axis is 4 km and minor axis is 1 km) was identified and dated to be 16.39 ± 0.34 Ma in age. It cuts and covers the Alaçatı andesitic pyroclastic and epiclastic deposits of the Ildır peninsula. Internal structures and igneous fabrics indicate a composite exogenous lava dome structure with short distance lava flows over a flat floor of Alaçatı ignimbrite. Emplacement of this Ildır composite lava dome was controlled by fissure-like volcanic activity along multiple fault lineaments as a result of extensional duplex – negative palm-tree lineaments which are related to the Miocene NW-SE directed sinistral strike-slip transtensional fault zone of the Karaburun peninsula. Comparison of the andesitic Ildır lava dome to all volcanic rocks of the Karaburun peninsula implies that the parental (more mafic) magma which formed the lava dome was generated by partial melting of a highly contaminated mantle source which had been modified by subduction-derived fluid/melt components. The Ildır melts were subsequently differentiated by fractional crystallization and crustal assimilation processes in the crust.