The collision of the Arabian Plate to Eurasia along the Bitlis-Zagros fold and thrust belt lead to the formation of a high plateau in Eastern Turkey. Due to this collision westward displacement and counter-clockwise rotation of the Anatolian block forming the right-lateral North Anatolian Fault Zone (NAFZ) and the left-lateral East Anatolian Fault Zone (EAFZ) resulted. Earthquake location studies in the Arabian Plate and Anatolian plateau display a lack of sub-crustal earthquakes in the region. This observation strongly point to the absence of the subducting Arabian Plate beneath the East Anatolian plateau. Lithospheric mantle is either thinned or totally removed in the region (Al-Lazki et al. 2003; Gök et al. 2003).
Moreover crustal thickness is assumed to be thinned (45-48 km) relative to its high elevation in the plateau area (Zor et al. 2003).Sengör et al. (2003) concluded that the East Anatolian plateau is supported by hot mantle and not a thick crust. Lower crustal flow is an important but still highly discussed geological process. Flow in the lower crust might allow extension at the surface to be distributed over a wider region than in the lithosperic mantle. This has far-reaching consequences for the development of relative vertical motions.
The Bitlis Massif, SE Anatolia, constitutes part of the Anatolide-Tauride block, north of the Arabian Plate. It is accreted to the Eastern Turkey. Metamorphic studies in the cover sequences of the Bitlis Massif allow to constrain the thermal evolution of the massif by metamorphic index minerals. A regionally distributed LT - HP metamorphic evolution is documented by glaucophane, relics of carpholite in chloritoid-bearing schists and pseudomorphs after aragonite in marbles. This indicates that (i) the Bitlis massif represents a terrane detached from the Arabian indentor that was stacked to form a nappe complex during the closure of the Neo-Tethys and (ii) that during late Cretaceous to Cenozoic evolution the Bitlis massif never evidenced temperatures over 400°C.
We will discuss the consequences of the Bitlis massif evolution - a cold continental block within an hot environment- for the Eastern Anatolian plateau.
