Electromagnetic imaging of the Thrace Basin and intra-pontide subduction zone, northwestern Turkey

Abstract

Magnetotelluric data were acquired at nine stations along an similar to80 km profile crossing the Thrace Basin and the Istranca Massif. These data were modeled using two-dimensional inverse techniques. The main findings are: (1) In the northernmost part of the profile, a wide (similar to21 kin) zone of the Istranca Massif with very high resistivity (>2000 ohm m) was imaged at a depth of 2.5 km, extending to similar to35 km depth. (2) Sedimentary rocks of the similar to63 km wide Thrace Basin (<75 ohm m) extend to a maximum depth of about 8 kin along the profile. (3) Below the Thrace Basin, an undulating similar to10 km thick zone of conductive lower crust with low resistivity (<75 ohm in) is present. (4) The depth to the lithospheric upper mantle (similar to250 ohm m) is about 45 kin beneath the Istranca Massif in the northernmost part of the profile, and rises to a lowest value of 17 km toward the southeast part of the, possibly indicating mantle uplift. (5) The location and existence of the Intra-Pontide subduction zone in the Thrace Basin is the subject of debate. We imaged for the first time a slab subducting to the north beneath the Istranca massif in the Thrace Basin. (6) Our georesistivity model also indicates that, in contrast to western Turkey, all electrically conductive asthenosphere is not present in northwestern Turkey.