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Mantle Dynamics beneath North Central Anatolia
C. Berk Biryol (University of Arizona), George Zandt (University of Arizona), Susan L. Beck (University of Arizona),
A. Arda Ozacar (Middle East Technical University), Hande E. Adiyaman (University of Arizona), Christine R. Gans
(University of Arizona)
The North Anatolian Fault Zone (NAFZ) is a transform structure that constitutes the boundary between the Anatolian Plate
to the south and the Eurasia Plate to the north. In this study we used shear-wave splitting analysis to study the upper mantle
dynamics beneath Anatolia region and the northward convex part of the NAFZ. The seismic data for our analysis comes from 39
broadband seismometers of the North Anatolian Fault passive seismic experiment (NAF) deployed at the central north Anatolia
between 2005 and 2008 (Figure 1). The instruments for this experiment are provided by the IRIS-PASSCAL consortium. Our
results reveal fairly uniform NE-SW trending anisotropy directions with decreasing delay times from west to east (Figure 1).
The existence of significant and uniform anisotropy across major tectonic boundaries and plate margins in the study area argues
for an asthenospheric source for the anisotropy rather than a lithospheric source. Our analysis also show that the lag times of
the measured anisotropy varies with short spatial wavelengths beneath central Anatolia and the eastern section of the region is
associated with lower lag times. We suggest the slab roll-back taking place along the Aegean trench and the different amounts
of trench retreat for the Aegean and Cyprean trenches contributes significantly to the upper mantle dynamics of the region and
induces a SW-directed astheonospheric flow with differential strengths from east to west (Figure 1). The similar patterns of
variation for both crustal strain filed and observed fast polarization directions also support the idea of SW asthenospheric flow
under the effects of Aegean and Cyprean slab roll-back processes.
References
Hatzfeld, D., Karagianni, E., Kassaras, I., Kiratzi, A., Louvari, E., Lyon-Caen, H., Makropoulos, K., Papadimitriou, P., Bock, G., & Priestley,
K., 2001. Shear wave anisotropy in the upper-mantle beneath the Aegean related to internal deformation, J. Geophys. Res., 106, 737-753.
McClusky, S., Reilinger, R., Mahmoud, S., Ben Sari, D. & Tealeb, A., 2003. GPS constraints on Africa (Nubia) and Arabia plate motions,
Geophys. J. Int., 155, 126–138.
Sandvol, E., Turkelli, N., Zor, E., Gok, R., Bekler, T., Gurbuz, C., Seber, D. & Barazangi, M., 2003. Shear wave splitting in a young continentcontinent
collision: An example from Eastern Turkey, Geophys. Res. Lett.,30(24), 8041.
Acknowledgements: This research was supported by NSF grant EAR0309838.
Results of splitting analysis from ETSE (Sandvol et al., 2003), NAF and Hatzfeld et al. (2001). BS: Bitlis Suture, IASZ: Izmir-Ankara-Erzincan Suture Zone, ITSZ: Inner
Tauride Suture Zone, IPSZ: Inner Pontide Suture Zone.The trench retreat rates (black arrows) are from McClusky et al. (2003).
II-226 | 2010 IRIS Core Programs Proposal | Volume II | Upper Mantle Structure and Dynamics