Structure of the crust and African slab beneath the central Anatolian plateau from receiver functions: New insights on isostatic compensation and slab dynamics

Structure of crust and African slab beneath central Anatolian plateau from receiver ABSTRACT The central Anatolian plateau in Turkey is a region with a long history of subduction, continental collision, accretion of continental fragments, and slab tearing and/or breakoff and tectonic escape. Central Anatolia is currently characterized as a nascent plateau with widespread Neogene volcanism and predominantly transtensional deformation. To elucidate the present-day crustal and upper mantle structure of this region, teleseismic receiver functions were calculated from 500 seismic events recorded on 92 temporary and permanent broadband seismic stations. Overall, we see a good correlation between crustal thickness and elevation throughout central Anatolia, indicating that the crust may be well compensated throughout the region. We observe the thickest crust beneath the Taurus Mountains (>40 km); it thins rapidly to the south in the Adana Basin and Arabian plate and to the northwest across the Inner Tauride suture beneath the Tuz Gölü Basin and Kır ş ehir block. Within the Central Anatolian Volcanic Province, we observe several low seismic velocity layers ranging from 15 to 25 km depth that spatially correlate with the Neogene volcanism in the region, and may represent crustal magma reservoirs. Beneath the central Taurus Mountains, we observe a positive amplitude, subhorizontal receiver function arrival below the Anatolian continental Moho at ~50–80 km that we interpret as the gently dipping Moho of the subducting African lithosphere abruptly ending near the northernmost extent of the central Taurus Mountains. We suggest that the uplift of the central Taurus Mountains (~2 km since 8 Ma), which are capped by flat-lying carbonates of late Miocene marine units, can be explained by an isostatic uplift during the late Miocene–Pliocene followed by slab breakoff and subsequent rebound coeval with the onset of faster uplift rates during the late Pliocene–early Pleistocene. The Moho signature of the subducting African lithosphere terminates near the southernmost extent of the Central Anatolian Volcanic Province, where geochemical signatures in the Quaternary volcanics indicate that asthenospheric material is rising to shallow mantle depths. This study represents the first analysis of a large data set collected as part of the Continental Dynamics–Central Anatolian Tectonics (CD-CAT) project that combines interdisciplinary expertise to investigate the structure and evolution of central Anatolia. As part of this project, 65 Streckeisen STS2 and Guralp CMG-3T broadband seismic stations were deployed in 72 locations throughout central Anatolia and operated for 2 yr between May 2013 and May 2015. The goals of the CD-CAT seismic deployment are multifaceted, but generally focus on better understanding the interplay between the complex Cenozoic evolution of the central Anatolian plateau and how it is reflected in the modern seismic structure of the region. In this study, we use P-wave receiver function images to investigate the crustal and uppermost mantle discontinuity structure beneath central Anatolia, and find links between crustal and upper mantle variations and Miocene–recent uplift and volcanism.