Tectono-stratigraphic evolution of the NE–SW-trending superimposed Selendi basin: Implications for late Cenozoic crustal extension in Western Anatolia, Turkey

Abstract

Selendi basin is located in the eastern part of Western Anatolia that is the easternmost part of the Aegean extensional province. In Western Anatolia, crustal extension resulted in exhumation of the mid-crustal units (the Menderes Massif) synchronously with volcano-sedimentary basin formation. The stratigraphic and tectonic features of the volcano-sedimentary succession reflect the exhumation processes and the modes of extension. We present new stratigraphical, sedimentological, structural and 40Ar/ 39Ar age data from the Neogene volcano-sedimentary fill of the NE–SW-trending Selendi basin. The data show that crustal extension in the region occurred in four distinct episodes and accommodated the exhumation of the Menderes Massif and the basin formation throughout the late Cenozoic. Late Oligocene to early Miocene detachment faulting (the Simav detachment fault, SDF) is attributed to the first episode. Clastic sedimentation and bimodal volcanism of ∼ 20.0–17.5 Ma (the Hacıbekir group) age was formed in the hanging wall of the SDF during the exhumation of northern Menderes Massif in the footwall. During second episode, the Menderes collapse occurred and was manifest by formation of the Gediz detachment fault (GDF) during the middle Miocene. Activity on the GDF has resulted in the exhumation of the central Menderes Massif in the Bozdağ area. During this period, the hanging wall of the GDF was dissected by NE–SW-trending high-angle oblique-slip cross-faults and accommodated clastic to lacustrine carbonate deposition and syn-sedimentary bimodal volcanism of 16–15 Ma (the İnay group). The third episode is represented by formation of NW–SE-trending sinistral and NE–SW-trending dextral strike- to oblique-slip faults and associated dip- to oblique-slip normal faults during the late Miocene, indicating that the area was deformed under a strike-slip tectonic regime. The faults localized alluvial sedimentation (the Kocakuz formation) and basaltic volcanism of 7–8 Ma (the Kabaklar basalt) in the Selendi basin. The last episode commenced by the start of the Plio-Quaternary. This period is represented by the currently active N–S extensional tectonic regime that resulted in the formation of E–W-trending high-angle normal faults that controls the present-day E–W-trending graben-type basin formation (e.g., Gediz and Simav grabens) and the Quaternary (1200–60 ka) basaltic volcanism.