Surface expression of eastern Mediterranean slab dynamics: Neogene topographic and structural evolution of the southwest margin of the Central Anatolian Plateau, Turkey

Abstract

The southwest margin of the Central Anatolian Plateau has experienced multiple phases of topographic growth, including the formation of localized highs prior to the Late\ud Miocene that were later affected by wholesale uplift of the plateau margin. Our new biostratigraphic data limit the age of uplifted marine sediments at the southwest plateau margin at 1.5 km elevation to <7.17 Ma, and regional lithostratigraphic correlations\ud imply that the age is <6.7 Ma. Single-grain CA-TIMS U-Pb zircon analyses from a reworked ash within the marine sediments yield dates as young as 10.6 Ma, indicating a maximum age that is consistent with the biostratigraphy. Our structural measurements within the uplifted region and fault inversion modeling agree with previous findings in surrounding regions, with early contraction followed by strike-slip and extensional deformation during uplift. Focal mechanisms from shallow earthquakes show that the extensional phase has continued to the present. Broad similarities in the change in the\ud tectonic stress regime (after 8 Ma) and the onset of surface uplift (after 7 Ma) imply that deep-seated process(es) caused post-7 Ma uplift. The geometry of lithospheric slabs beneath the plateau margin, Pliocene to recent alkaline volcanism, and the uplift pattern with\ud accompanying normal faulting point toward slab tearing and localized heating at the base of\ud the lithosphere as a probable mechanism for post-7 Ma uplift of the southwest margin. Considering previous work in the region, there appears to be an important link between slab dynamics and surface uplift throughout the Anatolian Plateau’s southern margin

A Miocene onset of the modern extensional regime in the Isparta Angle: constraints from the Yalvaç Basin (southwest Turkey)

“…We have no evidence that N-S shortening has affected our study area yet and conclude that the causes of this compression should be restricted to an area east of the Western Taurides, for instance, induced by collision of Cyprus with Turkey reflected in late Miocene shortening of the Kyrenia range (e.g. Schildgen et al 2012a;McCay and Robertson 2013).…”

“…Seismic tomographic images of van Hinsbergen et al (2010c) and Biryol et al (2011) clearly show that the Antalya slab is disconnected from the Aegean slab along a prominent transform (STEP, Govers and Wortel 2005). Biryol et al (2011) and Schildgen et al (2012a) suggested that the Antalya slab is a fragment of the Cyprus slab that for some reason rotated into a N-S orientation. Instead, we suggest that the thrust that the Antalya slab formed as a result of a separate, N-S striking subduction zone, that dips eastwards and until at least Pliocene time connected to the surface along the Aksu thrust and its offshore equivalents, with Bey Dağları in the lower plate, and the Taurides in the upper plate.…”

“…1c). Whereas high on the Tauride mountains, relict extensional basins are found with upper Miocene marine sediments (Deynoux et al 2005;Cosentino et al 2012;Schildgen et al 2012a), basins flanking the Tauride mountains to the east are filled by continental sediments and in places volcanics, and formed in an overriding plate setting of the present-day Cyprus subduction zone, as well as above the Antalya slab fragment. These intramontane basins include the Altınapa, Ilgın (or Akşehir) and Yalvaç Basins (Fig.…”

“…At depths beyond 50 km below the Isparta Angle, however, an east-dipping slab segment is imaged by seismic tomography (de Boorder et al 1998;Biryol et al 2011), which is still accommodating E-W compression as shown by earthquake solutions (Schildgen et al 2012a). Seismicity shows active deformation along the Akşehir-Afyon Fault Zone, the Ilgın Fault Zone, the Yaka-Eğirdir Fault Zone and the Konya Fault Zone (Fig.…”

“…From the east, the Bey Dağları platform is also overthrust by ophiolite-and carbonate-dominated thrust sheets known as the Antalya Nappes. The youngest thrusting at the contact with Bey Dağları-Western Taurides-occurred in the Early Miocene time (Hayward 1984) whilst Middle Miocene to Pliocene out-of-sequence thrusting in the Isparta Angle is dominated by the Aksu Thrust and the Kırkkavak strikeslip and normal-dominated fault (Dumont and Kerey 1975;Glover and Robertson 1998;Deynoux et al 2005;Flecker et al 2005;Çiner et al 2008;Schildgen et al 2012a) and their offshore equivalents in the Bay of Antalya (Hall et al 2014) (Fig. 1).…”