Resistivity structure of Denizli Çürüksu & Acıgöl Graben connection: Preliminary results from 3D inversion of magnetotelluric data

The western part of the Anatolian peninsula is defined with an N-S extensional regime and resulting graben systems, referred as the Aegean Extensional Province (AEP). The transition of this extensional regime in the west to E-W compressional regime in the east is bounded by the Isparta Angle, which is a reverse v-shaped major structure developed due to nappe emplacements and related clockwise and counter-clockwise rotations.

The study area is located at the eastern end of the Curuksu Graben and covers the western part of the Acigol Graben. Curuksu Graben is part of the Denizli Horst-Graben system and located between the junction point of three major grabens of the AEP in the west and Acigol Graben in the east. The development of the Graben systems in the AEP, including Curuksu and Acigol grabens, is resulted from two extensional periods interrupted by a compressional phase creating a disconformity between deformed ancient and undeformed neotectonic graben fills in the region. Denizli Horst-Graben System consists of incipient grabens and the modern graben (Curuksu Graben) which is developed with the introduction of the neotectonic regime with the latest Pliocene. This episodic development caused an inward development of normal faults. The compressional regime created many strike-slip and reverse faults in the region while many of the currently active normal faults with strike-slip components are resulted from the present day NNE-SSW extensional phase, including seismically active margin-bounding major faults with seismic hazard potential.

In this study, we have reassessed the data from 300 Magnetotelluric stations which were previously collected by a private contractor for geothermal research purposes. We have investigated the main properties of the data with Phase Tensor analysis and inverted it using ModEM software to reveal 3D subsurface conductivity structure of the area. Our analysis shows that the Phase Tensor ellipses for the highest frequencies indicate rather 1D behavior in compliance with the undeformed, nearly horizontal bedding of the neotectonic graben fills. The strike directions obtained through induction vectors and Phase Tensor ellipses reflects the dominant effect of the major faults and conductive basin fills. The recovered model from the 3D inversion results show the depth of the basin fills and conductivity anomalies due to normal faults controlling the basin development.