Abstract
Abstract We examined the thermal structure of the crust across complex deformation zones in SW Turkey using the Curie Point Depth (CPD) estimates and made comparisons of the thermal state of the crust with the seismic activity to provide insights for spatial limits of brittle failure in this region. The CPD estimates of SW Turkey from 80 overlapping blocks vary from 9 to 20 km. SW Turkey has two regions of shallow CPD. The shallow CPD region in the Uşak-Afyon zone in western part of the study area is caused by upper crustal thinning and shallowing of high conductivity lower crust. The other shallow CPD region is in the Central Anatolian Volcanic Province in the eastern part of the study area and is thought to be related to the presence of silicate melts in the shallow-level crust. A NNW-SSE trending belt of deep CPD region separates these two zones and is located along the boundary of high (west) and low (east) seismic activities. It is interpreted that the regional thermal structure in SW Turkey is mainly controlled by the processes associated with the African-Eurasian plate convergence zone. The N-S lithospheric extension above the subducting slab created a thermal dome in Western Anatolia in response to upwelling of asthenosphere. Post-collisional magmatism of Neogene-Quaternary age generated another thermal dome in the eastern area. Comparison of the CPD variations with the seismic activity has shown that large earthquakes occur near the margins of the inferred regional thermal domes. Low seismic activity within the regionally active seismic areas seems to be associated with shallow CPD and high heat flow.
Highlights
Thermal structure of the crust determines modes of deformation, depths of brittle and ductile deformation zones, regional heat flow variations, seismicity, subsidence/uplift patterns and maturity of organic matter in sedimentary basins
We demonstrate here that the regions of hotter crust in SW Anatolia are characterized by lower seismic activity. 1.1 Geological setting
The two regional thermal domes are located in the west and east of the study area and are separated by a zone of NNW-SSE trending deep Curie Point Depth (CPD)
Summary
Thermal structure of the crust determines modes of deformation, depths of brittle and ductile deformation zones, regional heat flow variations, seismicity, subsidence/uplift patterns and maturity of organic matter in sedimentary basins. The E-W trending deep CPD zone in the southern area is located beneath the Tauride mountain range, where a few low heat flow values (66 and 81 mWm−2) were measured previously based on silica geothermometry ( ̇Ilkısık, 1995) and low heat flow contours (20–60 mWm−2) in Fig. 5 (Tezcan and Turgay, 1989). We have correlated the estimated CPD and corresponding geothermal gradient values and the previous heat flow data (Tezcan and Turgay, 1989; ̇Ilkısık, 1995; ̇Ilkısık et al, 1997).
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