eEarth www.electronic-earth.net 1815-381X 1815-3828 3 1 2008 10.5194/ee-3-27-2008 http://www.electronic-earth.net/3/27/2008/ http://www.electronic-earth.net/3/27/2008/ee-3-27-2008.html http://www.electronic-earth.net/3/27/2008/ee-3-27-2008.pdf 27 35 2008-08-05 Geometry of the Turkey-Arabia and Africa-Arabia plate boundaries in the latest Miocene to Mid-Pliocene: the role of the Malatya-Ovacık Fault Zone in eastern Turkey R. Westaway robwestaway@tiscali.co.uk T. Demir A. Seyrek Faculty of Mathematics and Computing, The Open University, Eldon House, Gosforth, Newcastle-upon-Tyne NE3 3PW, UK Department of Geography, Harran University, 63300 Şanlıurfa, Turkey Department of Soil Science, Harran University, 63300 Şanlıurfa, Turkey also at: IRES, Newcastle University, Newcastle-upon-Tyne NE1 7RU, UK We suggest a working hypothesis for the geometry of the strike-slip faults that formed the boundaries between the Turkish, African and Arabian plates in the latest Miocene to Mid-Pliocene (LMMP), between ~7–6 Ma and ~3.5 Ma. This geometry differed significantly from the modern geometry; the northern Dead Sea Fault Zone (DSFZ) was located east of its present line and the TR-AR boundary was formed by the Malatya-Ovacık Fault Zone (MOFZ), located well north of the modern East Anatolian Fault Zone (EAFZ). The MOFZ is potentially the most problematic aspect of such a scheme, given the dramatically different interpretations of it that have been proposed. However, the presently-available evidence, albeit limited, is consistent with our proposed interpretation. Significant differences between the proposed LMMP fault geometry and the modern geometry include, first, the transtensional geometry of the MOFZ, the modern EAFZ being typically a left-lateral transform fault zone but with localized transpression. Second, the MOFZ slip rate was much lower than the ~9–10 mm a^−1 EAFZ slip rate; it is estimated as ~2–3 mm a^−1, having produced no more than ~8 km of slip during its approximately three million year long activity. The Euler vector is tentatively inferred to have involved relative rotation between the Turkish and Arabian Plates at ~0.85±0.15° Ma^−1 about a pole at ~37.75±0.15° N, ~38.8±0.3° E. 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