ROLE OF REGIONAL EXTENSION AND UPLIFT IN THE PLIOPLEISTOCENE EVOLUTION OF THE AKSU BASIN, SW TURKEY

The Aksu Basin, within the Isparta Angle area of SW Turkey, documents Plio-Pleistocene crustal processes at the interface between the Taurid e Mountains and the Eastern Mediterranean Sea. Basin sedimentation beg an in the Late Miocene, following an earlier history of emplacement of Mesozoic allochthonous units (Antalya Complex), Miocene basin develop ment and localized late Miocene compression (Aksu Phase). Late Miocene -Early Pliocene transtension deformed the Aksu Basin, exploiting pre-e xisting zones of structural weakness. During Early-Mid-Pliocene, muddy sediments accumulated in a shallow shelf sea (<150 m deep), open to t he Mediterranean Sea to the south. Regression in the Late Pliocene the n resulted in coarse deltaic progradation. Mature erosion surfaces dev eloped on adjacent elevated areas throughout the Pliocene and were acc ompanied by fanglomerate deposition along the high-relief western marg in of the basin. East-west extension then formed the present Aksu Basi n as a N-S half graben in the Late Pliocene-early Pleistocene associat ed with greatly enhanced fluvial downcutting. Accumulation of very ext ensive (600 km(2)) and locally thick (up to 250 m) cool-water Antalya tufa deposits then followed, prior to glacial times. Initial localized lacustrine carbonate deposition was followed by development of mainly algal carbonates that are thickest in the west. The terraced nature o f the tufa (terraces at 300, 250, 100 m above present sea level) is ex plained in terms of fluvial processes. Regional comparisons suggest a two-stage history for the Aksu Basin: first, Late Miocene-Early Plioce ne transtension and subsidence; secondly, Late Pliocene-Early Pleistoc ene rifting and marginal uplift. The overall tectonic setting reflects interplay between supra-subduction zone extension and tectonic 'escap e' of Anatolia westwards towards the Aegean.