Monoclinal flexure of an orogenic plateau margin during subduction, south Turkey
D. Fernández‐Blanco, G. Bertotti, A. Aksu and J. Hall
Journal name: Basin Research
Issue: Vol 31, No 4, August 2019 pp. 709 - 727
Info: Article, PDF ( 21.03Mb )
Geologic evidence across orogenic plateau margins enables the discrimination of the relative contributions of orogenic, epeirogenic and/or climatic processes that lead to growth and maintenance of those plateaus and their margins. Here, we discuss the mode of formation of the southern margin of the Central Anatolian Plateau (SCAP) and evaluate its time of formation using fieldwork in the onshore and seismic reflec-tion data in the offshore. In the onshore, uplifted Miocene rocks in a dip‐slope topog-raphy show monocline flexure over >100 km, km‐scale asymmetric folds verging south, and outcrop‐scale syn‐sedimentary reverse faults. On the Turkish shelf, verti-cal faults transect the basal latest Messinian of a 10 km fold where on‐structure syn-tectonic wedges and synsedimentary unconformities indicate pre‐Pliocene uplift and erosion, followed by Pliocene and younger deformation. Collectively, Miocene rocks delineate a flexural monocline at plateau margin scale that is expressed along our on‐offshore sections as a kink‐band fold with a steep flank 20–25 km long. In these reconstructed sections, we estimate a relative vertical displacement of 3.8 km at rates of ca. 0.5 mm/y, and horizontal shortening values <1 %. We use this evidence to-gether with our observations of shortening at outcrop, basin, plateau‐margin and forearc‐system scales to infer that the SCAP forms as a monoclinal flexure to accom-modate deep‐seated thickening and shortening since >5 Ma, and to contextualize the plateau margin as the forearc high of the Cyprus subduction system.