Crustal Structure of the Eastern Part of Central Anatolia (Turkey)

Authors: HÜSEYİN YILMAZ, SEVDA ÖZEL

Abstract: This study aims to examine crustal structure in the eastern part of central Anatolia using the magnetotelluric (MT) method. MT data have been collected from 37 stations along a north-south 220 km profile crossing in succession the Tokat Massif (Pontide basement), the Ankara-Erzincan Suture Zone, the Kırşehir Massif, the Pınarbaşı-Divriği Ophiolitic Belt and the Tauride-Anatolide Belt. Data were modelled to derive a geo-electrical model using 2-dimensional inverse techniques. Low resistivity values (<38 Ohm.m) extend to a maximum depth of 7 km beneath the Sivas Basin, 4 km in the Kangal Basin, 10 km in the Gürün Basin, 6 km in the Ovacık Basin and 6 km in the Elbistan Basin and are interpreted as sediment infill. Three high resistive zones (>981 Ohm.m) coincide with the southern part of the Pontide Magmatic Arc, the Kırşehir Block and the Tauride-Anatolide Belt and are interpreted as upper crust of igneous and metamorphic origin. Low resistivity values (< 981 Ohm.m) are identified below the upper crust and the layer accepted as lower crust ranges from 10-15 km beneath the high resistive zones. Total crust thickness is approximately 45 km in the Tokat Massif, Kırşehir Massif and Tauride-Anatolide Platform. Two vertical conductive zones have been detected beneath the Ankara-Erzincan Suture in the north and the Divriği-Pınarbaşı Ophiolitic Belt in the south. The northern conductive zone identifies the Ankara-Erzincan Suture and the southern conductive zone corresponds to the Divriği-Pınarbaşı Ophiolitic Belt where it provides evidence for an Inner Tauride Suture. The relationship between the gravity and resistivity data has been researched and the high gravity anomalies were found to be consistent with high conductive zones along the MT profile.

Keywords: crustal structure, magnetotelluric, sutures, Central Anatolia, Turkey

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