Crustal Structure at the vicinity of Nigde Massif and Central Anatolian Fault Zone from Magnetotelluric Data

Abstract:

Three magnetotelluric (MT) profiles were constructed to examine the electrical resistivity strucuture of a metamorphic core complex renown as Niğde massif and a northeast - southwest aligned fault zone (Central Anatolian Fault Zone, CAFZ) bounding this massif on the east in Central Anatolia. Nigde massif is a crystalline dome close to Inner-Tauride suture at the southern part of Central Anatolian Crystalline Complex. The sinistral CAFZ (in the south it is called Ecemis fault) is a ~700 km long, 2 to 80 km wide zone with an offset of 60 to 80 km. Northwest-southeast aligned Tuz Gölü (Salt Lake) and Derinkuyu faults are other major features that shape up the study area. A three-dimensional numerical modeling routine based on data-space modeling (WSINV3DMT) was used to invert the MT data collected at 85 high quality soundings. A mesh with 76 x 74 x 40 (7 layers for air) cells was used during the inversions. The resulting models suggest that (i) there is a low conductivity dome-like anomaly that coincides with the Nigde massif (presumably matches with Uckapili granite). (ii) Beneath this low conductivity anomaly there is a deeper (>20 km) high conductivity zone caused by partial melting (iii) Ecemis fault near Pozanti appears as a low to high conductivity interface. (iv) Likewise, Tuz Gölü and Derinkuyu faults appear as a low to high conductivity interfaces representing barriers for fluid flow (v) Adana basin sediments show high conductivity values (vi) Mt. Hasan and Mt. Karaca and the volcanic complexes in between them show highly conductive features in their roots, but (vi) older Mt. Erciyes lacks such a deep conductor.