Geothermal Reconnaissance Of The Marmara Sea Region (Nw Turkey)- Surface Heat Flow Density In An Area Of Active Continental Extension

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Journal Article: Geothermal Reconnaissance Of The Marmara Sea Region (Nw Turkey)- Surface Heat Flow Density In An Area Of Active Continental Extension

Abstract
Northwestern Anatolia is an area of significant neotectonic activity. The Northern Anatolian Fault splits into different branches and the tectonic regime changes from translation to a combination of extension and translation. High seismicity as well as frequent and in places large hot springs are related to these tectonic features. The present study aims at characterising the geothermal situation of this area by detailed heat flow density mapping and thermal spring studies. High-resolution temperature logs and measurements of rock thermal conductivity were used to determine the terrestrial heat flow density. Because of the shallowness of the available drillholes (maximum depth of 200 m), hydraulic influences on the thermal profiles had to be taken into account. Conductive heat flow density was calculated considering possible convective effects due to vertical water movements. In spite of these hydraulic influences, the temperature distribution showed stability over a time period of at least one year. Stationary models could therefore be applied. Terrestrial surface heat flow density varies regionally from 35 to 115 mW/m2, with a mean value of 60 mW/m2. The heat flow density map shows that the extensional tectonics of the region south of the Marmara Sea is characterised by higher heat flow density values. Regions with low tectonic activity such as parts of European Turkey or regions with compressional and translational tectonics have average or slightly lower values. The spatial pattern of thermal springs in the Marmara Sea region does not coincide with the terrestrial heat flow density distribution. Their appearance is bound to neotectonic faults (= locally enhanced vertical permeabilities).

Authors 
Martin Pfister, Ladislaus Rybach and Sakir Simsek








Published Journal 
Tectonophysics, 1998





DOI 
10.1016/S0040-1951(98)00032-8


 

Citation

Martin Pfister,Ladislaus Rybach,Sakir Simsek. 1998. Geothermal Reconnaissance Of The Marmara Sea Region (Nw Turkey)- Surface Heat Flow Density In An Area Of Active Continental Extension. Tectonophysics. (!) .