Petrogenesis of post-collisional Middle Eocene volcanism in the Eastern Pontides (NE, Turkey): Insights from geochemistry, whole-rock Sr-Nd-Pb isotopes, zircon U-Pb and 40Ar-39Ar geochronology

The debate about whether Eocene magmatism is considered to be post-collisional or subduction-related not still continues. Here we offer new 40 Ar- 39 Ar ad U-Pb zircon geochronology, mineral chemistry, bulk rock and Sr-Nd-Pb isotope geochemistry data obtained from the southern dike (SD) suite, in comparison with northern (ND) Eastern Pontides. geochronological indicate that SD suite erupted between 45.89 45.10 Ma corresponding Lutetian (Middle Eocene). magmas of ND are characterised by slightly more alkaline affinity compared suite. trace rare earth element (REEs) content large ion lithophile (LILEs; Sr, K 2 O, Ba, Rb) enrichment depletion Nb, Ta, TiO elements different degree high Th/Yb ratios, which forming suites were derived lithospheric mantle sources enriched mostly slab-derived fluids spinel stability field. Nd Pb radiogenic ratios dikes support view magma for hydrous group (H-SD) was a relatively source than other suites. anhydrous (A-SD) display similar geochemical features moderate light (LREE)/heavy (HREE) while H-SD has respectively lower LREE/HREE indicating higher melting degree. Detailed considerations alkalinity, partial studied volcanic rocks affinity, whereas throughout show increments rate In comparative interpretations, geodynamic evolution differences petrogenetic character both parts Pontides may explained degrees net veined initially metasomatized subduction during asthenospheric upwelling due fragmented asymmetric delamination extensional tectonic environment.