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

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 (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.

Anahtar Kelimeler:

crustal structure, magnetotelluric, sutures, Central Anatolia, Turkey

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

Keywords:

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

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AKN, H. 1978. Geologie, magmatismus und lager-staettenbildung im ostpontischen Gebirge-Türkei aus der Scht der Plattentektonik. Geologisches Rundschau 68, 253–283.
ALPASLAN, M., YıLMAZ, H. & TEMEL, A. 2004. Geochemistry of post- collision Pliocene-Quaternary Karasar Basalt (Divriği-Sivas, Eastern Turkey): evidence for partial melting processes. Geologica Carpathica 55, 487–500.
ANDREW, T. & ROBERTSON, A.H.F. 2002 The Beyflehir-Hoyran-Hadim Nappes: genesis and emplacement of Mesozoic marginal and oceanic units of the northern Neotethys in southern Turkey. Journal of Geological Society of London 159, 529–543.
AYDıN, İ., KARAT, H.İ. & KOÇAK, A. 2005. Curie-point depth map of Turkey. Geophysical Journal International 162, 633–640.
BAYRAK, M., GÜRER, A. & GÜRER, Ö.F. 2004. Electromagnetic imaging of Thrace Basin and Intra-Pontide subduction zone, Northwestern Turkey. International Geology Review 46, 64–74.
BAYRAK, M., GÜRER, A., GÜRER, Ö.F., İLKıfiıK, O.M. & BAfiOKUR, A.T. 2006. Mohr-circle-based rotational invariants of a magnetic data set from the Thrace region of Turkey. Turkish Journal of Earth Sciences 15, 95–110.
BEBLO, M., BJORNSSON, A., ARNASON, K., STEIN, B. & WOLFGRAM, P. 1983. Electrical conductivity beneath Iceland – constraints imposed by magnetotelluric results on temperature, partial melt, crust and mantle structure. Journal of Geophysics 53, 16–23.
BEKTAfi, O. 1984. Upper Cretaceous shoshonitic volcanism and its importance in the Eastern Pontides. Karadeniz Teknik Üniversitesi Yerbilimleri Dergisi Jeoloji 3, 53–62 [in Turkish with English abstract].
BERGOUGNAN, H. 1976. Structure de la Chaine pontique dans le Haut- Kelkit (Nord-Est de l’Anatolie). Bulletin de la Société Géologique de France 7, 675–686.
BOCCALATTI, M., GOCEV, P. & MANETTI, P. 1974. Mesozoic isotopic zones in the Black Sea Region. Bolletine Della Societa Italiana 93, 547–565.
BUKET, E. 1982. Petrochemical characteristics of the Erzincan-Refahiye ultramafic and mafic rocks and their correlations with other occurences. Hacettepe Üniversitesi Yerbilimleri 9, 43–65 [in Turkish with English abstract].
CATER, J.M.L., HANNA, S.S., RIES, A.C. & TURNER, P. 1991. Tertiary evolution of the Sivas Basin, Central Turkey. Tectonophysics 195, 29–46.
CAGNIARD, L. 1953. Basic theory of the magneto-telluric method of geophysical prospecting. Geophysics 18, 605–635.
CLARK, M.S. & ROBERTSON, A.H.F. 2002. The role of the Early Tertiary Ulukıflla Basin, southern Turkey in suturing of the Mesozoic Tethys ocean. Journal of the Geological Society, London 159, 673–690.
CLARK, M.S. & ROBERTSON, A.H.F. 2005. Uppermost Cretaceous–Lower Tertiary Ulukıflla Basin, south-central Turkey: sedimentary evolution of part of a unified basin complex within an evolving Neotethyan suture zone. Sedimentary Geology 173, 15–51.
DEMİRTAfiLı, E. 1977. Toros Kuflağı’nın petrol potansiyeli [The petroleum potential of the Taurus Belt]. Türkiye Üçüncü Petrol Kongresi. Bildiriler, Konferans ve Açık Oturumlar, 55–61 [in Turkish].
DUBA, A.G., HUENGES, E., NOVER, G., WILL, G. & JÖDICKE, H. 1989. Impedance of black shale from Münsterland I borehole: an anomalous good conductor? Geophysical Journal 94, 413–419.
DUVARCı, E. 1993. Rejyonal Elektrik Haritalar Projesi: Sivas Tersiyer Özdirenç Etüdü [The Project of Regional Electricity Maps: Survey of Tertiary Resistivity of Sivas]. General Directorate of Mineral Research and Exploration (MTA) Report no. 9701 [in Turkish, unpublished].
EREZ, K. 1974. Sivas Celalli Kuyusunda Hız Tayini [The Velocity Designation in Celalli, Sivas Borehole]. General Directorate of Mineral Research and Exploration (MTA) Report no. 5783 [in Turkish, unpublished].
ERKAN, E.N., ÖZER, S., SÜMENGEN, M. & TERLEMEZ, İ. 1978. Sarız, fiarkıflla, Gemerek, Tomarza Arasının Temel Jeolojisi [Main Geological Characteristics of the Area Between Sarız, fiarkıflla, Gemerek and Tomarza]. General Directorate of Mineral Research and Exploration (MTA) Report no. 5646 [in Turkish, unpublished].
FLOYD, P.A., YALNıZ, M.K. & GÖNCÜO⁄LU, M.C. 1998. Geochemistry and petrogenesis of intrusive and extrusive ophpiolitic plagiogranites, Central Anatolian Crystalline Complex, Turkey. Lithos 42, 225–240.
FLOYD, P.A., GÖNCÜO⁄LU, M.C., WINCHESTER, J.A. & YALNıZ, M.K. 2000. Geochemical character and tectonic environment of Neotethyan ophiolitic fragments and metabasites in the Central Anatolian Crystalline Complex, Turkey. In: BOZKURT, E., WINCHESTER, J.A. & PIPERJAD (eds), Tectonics and Magmatism in Turkey and the Surrounding Area. Publications 173, 183–202.
FROST, B.R., FYFE, W.S., TAZAKI, K. & CHAN, T. 1989. Grain-boundary graphite in rocks and implications for high electrical conductivity in the lower crust. Nature 340, 134–136.
GEDİKO⁄LU, A. 1978. The Harshit Granite Complex and Its Surrounding Rocks (Giresun-Doğankent). PhD Thesis, Karadeniz Teknik Üniversitesi, Trabzon [in Turkish with English abstract, unpublished].
GOUGH, D.I. 1986. Seismic reflectors, conductivity, water and stress in
the continental crust.
GÖKTEN, E. 1993. Ulafl (Sivas) doğusunda Sivas Havzası güney kenarının jeolojisi: İç Toros Okyanusu’nun kapanması ile ilgili tektonik geliflim [Geology of the southern boundary of Sivas Basin in the east of Ulafl (Sivas-Central Anatolia): Tectonic development related to the closure of Inner Tauride Ocean]. Turkish Association of Petroleum Geologists Bülletin 5, 35–55 [in Turkish with English abstract].
GÖKTEN, E. & FLOYD, P. 1987. Geochemistry and tectonic environment of the fiarkıflla area volcanic rocks in Central Anatolia, Turkey. Mineralogical Magazine 51, 553–559.
GÖNCÜO⁄LU, M.C. 1986. Orta Anadolu Masifinin güney ucundan jeokronolojik yafl bulguları [Geochronologic age data from the southern part of the Central Anatolian Massif]. General Directorate of Mineral Research and Exploration (MTA) Bulletin 105/106, 111–124 [in Turkish with English abstract].
GÖNCÜO⁄LU, M.C. & TÜRELİ, T.K. 1993. Petrology and geodynamic setting of plagiogranites from Central Anatolian Ophiolites (Aksaray-Türkiye). Turkish Journal of Earth Sciences 2, 195–203.
GÖNCÜO⁄LU, M.C., DİRİK, K. & KOZLU, H. 1996–1997. Pre-alpine and alpine terranes in Turkey: explanatory notes to the terrane map of Turkey. Annales Géologiques Des Pays Helleniques 37, 515–536.
GÖNCÜO⁄LU, M.C., DİRİK, K., ERLER, A. & YALıNıZ, K. 1994. Geology of the Eastern Part of the Central Anatolian Massif, Part 4: The Relationship Between the Central Anatolian Massif and Sivas Basin. Middle East Technical University-Turkish Petroleum Company Report [in Turkish, unpublished].
GÖNCÜO⁄LU, M.C., TOPRAK, V., KUSÇU, I., ERLER, A. & OLGUNE. 1991. Geology of the Western Part of the Central Anatolian Massif, Part 1: Southern Section. Turkish Petroleum Company Report no. 2909 [in Turkish, unpublished].
GÖRÜR, N., TÜYSÜZ, O. & fiENGÖR, A.M.C. 1998. Tectonic evolution of the Central Anatolian Basins. International Geology Review 40, 831–850.
GÖRÜR, N., OKTAY, F.Y., SEYMEN, İ. & fiENGÖR, A.M.C. 1984. Paleotectonic evolution of Tuz Gölü basin complex, central Turkey. In: DIXON, J.E. & ROBERTSON, A.H.F. (eds), The Geological Evolution of the Eastern Mediterranean. Geological Society, London, Special Publications 17, 81–96.
GRANT, F.S. & WEST, G.F. 1965. Interpretation Theory in Applied Geophysics. McGraw-Hill, New York.
GUPTAP.K. & JONES, A. 1990. Electrical resistivity structure of Flathead basin in southeastern British Columbia. Canadian Journal of Earth Sciences 27, 1061–1073.
HAAK, V., STOLL, J. & WINTER, H. 1991. Why is the electrical resistivity around the KTB hole so low? Physics of the Earth Planetary Interior 66, 12–13.
HERSIR, G.P. & BJÖRNSSONN, A. 1991 Geophysical Exploration for Geothermal Resources Principles and Application. National Energy Authority, Geothermal Division Grensasvegur, 9 108 Reykjavik, Iceland.
HYNDMAN, R.D. & HYNDMAN, D.W. 1968. Water saturation and high electrical conductivity in the lower crust. Earth and Planetary Science Letters 4, 427–432.
JAıN, S. 1964. Electrically conductivity of the crust and upper mantle at Eskdalemuir, southern Scotland. Nature 203, 631–632.
JONES, A.G. 1987. MT and reflection: an essential combination. Geophysical Journal of The Royal Astronomical Society 89, 7–18.