An Assessment on Heat Source of Geothermal Fields in Buyuk Menderes and Gediz Grabens, Sw Turkey
The extensional stress regime is very effective in western Turkey since the Oligocene. Geothermal fields are
positioned on the high-angle normal faults on the hanging wall of the detachment faults along the northern and southern
margins of the Buyuk Menderes and Gediz grabens, respectively. The alignments of the geothermal fields with high
temperatures on the both sides of the detachment fault are remarkable. This situation raises the question that whether it is only
a channel for the hot waters of the shear zones, or is it a physical mechanism that increases the existing geothermal gradient
by creating friction heat. The shallow mantle of a thinned crust (33 km) is the heat source due to large extension rates,
resulting in increased heat flow. The high deformation rates of the detachment faults and the fairly high exhumation rate of the
central Menderes metamorphic core complex during continental extension could cause an extra heat flow.
Index Terms—Buyuk Menderes graben, detachment fault, extensional tectonics, shear heating.