Eocene-Quaternary magmatic activity in the Aegean: Implications for mantle metasomatism and magma genesis in an evolving orogeny

Abstract

We present a compilation and comparison of geochemical data of Aegean Eocene to Recent magmatic rocks: (1) North Anatolian Eocene magmatic rocks (NAEM), (2) Aegean to west Anatolian Oligocene–Miocene magmatic rocks (AOMM), (3) Pliocene–Quaternary South Aegean volcanic arc (SAVA), (4) Pliocene–Quaternary Denizli–Isparta volcanics (DIV), and (5) Na-alkaline basalts with intra-plate geochemical affinity (IPV). These rocks are also compared with Miocene Galatean volcanics (GVP) from central Anatolia.The NAEM, SAVA and GVP show similar geochemical features indicative of a subduction-related origin in which subducted oceanic plate contaminated the overlying mantle wedge. The distinct geochemical features of the AOMM reflect derivation from an intensely metasomatised mantle source, resulting from partial subduction and accretion of both continental and oceanic assemblages in the fore-arc of a southward migrating subduction system. These features provide an insight into the history of the distinct types of mantle metasomatism in the region and into its geodynamic evolution — an evolution that include complex interaction of subduction roll-back, slab break-off, strike-slip faulting along major transfer zones, block rotations and core complex formation.Thus, the Eocene to recent magmatism in the region was controlled by various tectonic events: (1) the NAEM was most probably related to break-off of the subducted slab in western Anatolia, (2) magmatic activity in the western AOMM was controlled by rotational extension around poles in northern Greece developed in response to rotational roll-back of the Hellenic subduction system, (3) while AOMM magmatism in the east is closely associated with core complex formation and asthenosphere-related thermal input along a ~N–S-trending slab tear. In contrast, the rocks of the DIV and IPV carry asthenospheric mantle geochemical signatures indicative of roll-back induced asthenospheric upwelling in Rhodope to NW Anatolia, and slab tear-induced asthenospheric upwelling beneath the Menderes Core Complex.