Magmatic evolution of the Eastern Anatolian High Plateau

The Eastern Anatolia High Plateau is an activelydeforming continental collision zone with a long-lasting volcanism from the end of Middle Miocene to historical times. It hosts some of the largest volcanic centers and plateaus of the circum Mediterranean region (e.g. Mt. Ararat, Nemrut, Tendurek and Suphan).Eastern Anatoliais a unique place in the world where the continental crust, most of which is represented by an accretionary complex, directly overlies the 

asthenospheric mantle [1]. So, the region is devoid of a lithospheric mantle. This unusual setting has been proposed to be linked to a major slab-steepening & breakoffevent [1, 2]. 

To better understand the magma genesis and the geodynamic setting, we have been conducting a series of projects in E Anatolia since 2007, carefully studying the stratigraphy of the volcanoes and conducting radiometric datings and geochemical analyses. Results from our new and rather comprehensive database have revealed that the volcanism initiated around the N of Lake Van in the south at ~15 Ma with the eruption of calc-alkaline lavas containing a distinct subduction signature. The geochemical character of the volcanism changed from calc-alkalineto alkaline both in time (from Mid. Miocene to Quaternary) and space (from N to S), while the subduction signature temporally diminished. Our melting models suggest a region-wide temporal change from garnet- to spinel-dominated mantle mineralogy and an increase in the degree of melting. Our AFC and EC-AFC models indicate a significant crustal involvement increasing to the south. These findingsmay imply that the steepening of the slab has been a much faster event than we previously anticipated and the magma generation might have been 

influenced by the reformation of a new lithospheric mantle.

 

[1] Şengör et al. (2003) GRL, 30 (24) 8045. [2]Keskin (2003) GRL, 30 (24) 8046.