Geophysical Investigation of the Hematite Zones in Koçarlı-Demirtepe (Aydın/Turkey)

Abstract

The Koçarlı-Demirtepe iron ore deposit area was investigated with geophysical methods (magnetic and resistivity) in order to determine the presence of iron deposits, which are important in cement production, in the Koçarlı/Aydın region. The study area is locally known as “iron hill” and iron ore was produced in ancient times from three galleries. In this study, magnetic, vertical electrical sounding (VES) and electrical resistance tomography (ERT) methods were applied to determine the actual geometry and reserves. Magnetic investigations were carried out in order to obtain a general idea about the approximate boundaries of the possible hematite zone. The resulting total magnetic field anomaly map was used to define the boundaries of the hematite zones. The depth of the structure was calculated to be about 27 m with a 2-D inversion method for a dyke model. Three profiles of ERT and five vertical electric soundings were measured in order to define the iron ore geometry. A 2-D inversion method was applied to the multi-electrode data to create an ERT model of the hematite zone geometry and the vertical structural variations. In order to obtain the vertical cross sections of the survey area, a 2-D inversion method was applied to the ERT and VES data. The data sets of vertical electric sounding were combined and modeled as a profile. Results of the 2-D inversion were supported by the ERT model. The depth values obtained from the ERT are in agreement with those from 2-D inversion of magnetic data. According to these results, the thickness of the hematite zone was determined to be 10 m. Finally, the iron ore and its geometry were defined. The strike of the ore body was found to be northwest–southeast and its thickness was found to be about 10–12 m. With respect to these dimensions, approximately 10,000 m³ of iron ore was estimated.