THE AIRBORNE MAGNETIC SIGNATURE OF GÖKOVA GULF

Year 2013, Volume: 147 Issue: 147, 169 - 177, 01.12.2013

Uğur Akın Ahmet Üçer

Abstract

The gulf of Gökova, which is located in the Aegean Extensional Zone of Turkey, has been a point of interest for many investigators. This gulf takes place within the regional extensional tectonic regime in NS directions. The extension of Western Aegean in N-S directions has also formed many other grabens which are perpendicular to grabens in E-W directions. The gulf has an approximate length of 100 km’s (in EW) and 25 km’s (in NS). Datça and Bodrum peninsulas take place towards south and north of the gulf, respectively. In recent years, Full Tensor Gradiometer (FTG) potential field methods have widely been used among the gravity and magnetic methods. In the past, vertical component of the magnetic field has been measured as it had been done in the gravitational method. However; this method has turned into total area measurements (x, y and z components) in recent applications. This method was applied to the data of total aeromagnetic field. FTG method was applied by measuring the data of total aeromagnetic field components. The FTG analysis (Full Tensor Magnetic Gradiometer) of the magnetic anomaly existing in the gulf was performed in order to give a different point of view to the geological structure of the gulf of Gökova in which there were intense seismic activities. Field components (Tx, Ty, Tz) of the aeromagnetic anomaly in the gulf of Gökova were estimated. Components obtained at the end of conversion were then applied the derivatives of Txx, Txy, Txz, Tyy, Tyz, Tzz and information about the location of the geological source which causes anomaly were taken. It was observed that the northern boundary of the ultramafic body had continued up to a distance of 9 km’s towards the northern coast of the gulf of Gökova. The anomaly in the gulf showed that ultramafic rocks, peridotites and the ophiolitic mélange of Datça peninsula had continued within the sea. The method has been useful in correct mapping of different geological units that have variable magnetic sensitivities and in revealing their locations

Keywords

Gökova gulf, Datça, Bodrum, Magnetic, Gradient, Tensor, FTG

References

• Akın, U., Duru M., 2006. Türkiye Isı Akısı Haritası (manyetik verilerden) raporu, Maden Tetkik ve Arama Genel Müdürlüğü Rapor No: 10840, (yayımlanmamış) Ankara.
• Akın, U., Çiftçi, Y., 2011. Türkiye’nin Yapısal Süreksizlikleri: Jeolojik-Jeofizik (Gravite ve Manyetik) Analiz. Maden Tetkik ve Arama Genel Müdürlüğü Monografi Serisi No: 6, 155 sf.
• Ateş, A., 1999. Possibility of deep gabbroic rocks, east of Tuz Lake, central Turkey, interpreted from aeromagnetic data. J. Balkan Geophys. Soc., 2,15–29.
• Aydın, İ., Karat, H.İ., Koçak, A., 2005. Curie-point depth map of Turkey. Geophys. J. Int. 162, 633-640.
• Bracken, E.B., Brown P.J., 2005. Reducing Tensor Magnetic Gradiometer Data for Unexploded Ordnance Detection. Scientific Investigations Report 2005-5046 U.S. Geological Survey.
• Christensen, A., Rajagopalan, S., 2000. The magnetic vector and gradient tensor in mineral and oil exploration: Preview, 84, 77.
• FitzGerald, D., Argast, D., Paterson, R., Holstein, H., 2010. Full tensor magnetic gradiometry processing and interpretation developments Part A. Adding new value to Electromagnetic, Gravity and Magnetic Methods for Exploration. EGM 2010 International Workshop, Capri, Italy.
• Görür, N., Sengör, A. M. C., Sakinü, M., Akkök, R., Yiğitbaş, E., Oktay, F.Y., Barka, A., Sarica, N., Ecevitoğlu, B., Demirbağ, E., Ersoy, Ş., Algan, O., Güneysu, C., Aykol, A., 1995. Rift formation in the Gökova region, southwest Anatolia: implications for the opening of the Aegean Sea. Geological Magazine, 132 (06) 637-650.
• Heath, P., Heinson, G., Greenhalgh, S., 2003. Some comments on potential field tensor data: Exploration Geophysics, 34, 57–62.
• Kurt, H., Demirbağ, E., Kuşçu, İ., 1999. Investigation of the submarine active tectonism in the Gulf of Gökova, southwest Anatolia–southeast Aegean Sea, by multi-channel seismic reflection data. Tectonophysics 305, 477-496.
• Mataragio, J., Jorgensen, G., Carlos, D.U, Braga, M., 2011. State of the Art Techniques for Iron Oxide Exploration. Twelfth International Congress of the Brazilian Geophysical Society. August 15-18.
• MTA, 2002, 1/500.000 ölçekli Türkiye Jeoloji Haritaları, Maden Tetkik ve Arama Genel Müdürlüğü, Ankara
• Murphy, C.A., 2004. The Air-FTG airborne gravity gradiometer system, in R.J.L. Lane, editor, Airborne Gravity 2004 – Abstracts from the ASEGPESA Airborne Gravity Workshop: Geoscience Australian Record 2004/18, 7-14.
• Murphy, C.A., 2007. Interpreting FTG Gravity data using horizontal Tensor components: EGM 2007 International Workshop - Innovation in EM, Grav and Mag methods: new Perspective for Exploration.
• Murphy, C.A., Brewster, J., 2007. Target delineation using Full Tensor Gravity Gradiometry data : ASEG, Perth, Australia, Extended Abstracts.
• Murphy, C.A., Dickinson, J. L., 2010.Geological Mapping and Targeting using Invariant Tensor analysis on Full Tensor Gravity data. EGM 2010 International Workshop Adding new value to Electromagnetic, Gravity and Magnetic Methods for Exploration Capri, Italy, April 11-14.
• Pedersen, L.B., Rasmussen, T.M., (1990) The gradient tensor of potential field anomalies: some implications on data collection and data processing of maps: Geophysics, 55, 1558-1566.
• Rompel, A.K.K., 2009. Geological Apllications for FTMG. 11th SAGA Biennial Technical Meeting and Exhibition Swaziland, 16-18 September, pages 39-42.
• Schmidt, P.W., Clark, D.A., 2000. Advantages of measuring the magnetic gradient tensor: Preview, 85, 26–30.
• Şenel, M. 2007. Likya Naplarının Özellikleri ve Evrimi, Menderes Masifi Kolokyumu, 51-55s., İzmir.
• Wan, L., Zhdanov, M.S., 2008. Focusing inversion of marine full-tensor gradiometry data in offshore geophysical exploration. SEG Las Vegas 2008 Annual Meeting.