Regional Geothermal Characterisation of East Anatolia from Aeromagnetic,Heat Flow and Gravity Data |
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| Authors: | Özcan Bekta? Dhananjay Ravat Aydin Büyüksaraç Funda Bilim Abdullah Ate? |
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| Institution: | (1) Faculty of Engineering, Department of Geophysical Engineering, Cumhuriyet University, 58140 Sivas, Turkey;(2) Department of Geology 4324, Southern Illinois University Carbondale, Carbondale, Illinois, 62901-4324, United States;(3) Faculty of Engineering, Department of Geophysical Engineering, Ankara University, 06100 Besevler, Ankara, Turkey |
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| Abstract: | East Anatolia is a region of high topography made up of a 2-km high plateau and Neogene and Quaternary volcanics overlying
the subduction-accretion complex formed by the process of collision. The aeromagnetic and gravity data surveyed by the Mineral
Research and Exploration (MTA) of Turkey have been used to interpret qualitatively the characteristics of the near-surface
geology of the region. The residual aeromagnetic data were low-pass filtered and analyzed to produce the estimates of magnetic
bottom using the centroid method and by forward modelling of spectra to evaluate the uncertainties in such estimates. The
magnetic bottom estimates can be indicative of temperatures in the crust because magnetic minerals lose their spontaneous
magnetization at the Curie temperature of the dominant magnetic minerals in the rocks and, thus, also are called Curie point
depths (CPDs). The Curie point depths over the region of Eastern Anatolia vary from 12.9 to 22.6 km. Depths computed from
forward modelling of spectra with 200–600 km window sizes suggest that the bottom depths from East Anatolia from the magnetic
data may have errors exceeding 5 km; however, most of the obtained depths appear to lie in the above range and indicate that
the lower crust is either demagnetized or non-magnetic. In the interpretation of the magnetic map, we also used reduction-to-pole
(RTP) and amplitude of total gradient of high-pass filtered anomalies, which reduced dipolar orientation effects of induced
aeromagnetic anomalies. However, the features of the RTP and the total gradient of the high-pass filtered aeromagnetic anomalies
are not highly correlated to the hot spring water locations. On the other hand, many high-amplitude features seen on the total
gradient map can be correlated with the ophiolitic rocks observed on the surface. This interpretation is supported by Bouguer
gravity data. In this paper, we recommend that the sources of the widespread thermal activity seen in East Anatolia must be
investigated individually by means of detailed mapping and modelling of high resolution geophysical data to assess further
the geothermal potential of the region. |
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| Keywords: | Aeromagnetic anomalies gravity data power spectrum curie point depth forward modelling upper crustal structure |
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