Tectonic-sedimentary evolution of the northern margin of Gondwana during Late Palaeozoic – Early Cenozoic time in the Eastern Mediterranean region: evidence from the Central Taurus Mountains, Turkey.

Abstract

The Taurus Mountains are an E-W trending mountain range in southern Turkey, with an elevation of up to 3500 m. In the south central Taurides, the Beysehir-Hoyran-Hadim nappes, a series of thrust sheets of Palaeozoic to Early Cenozoic age, are emplaced onto a relatively autochthonous Tauride platform, known as the Geyik Dag. These thrust sheets consist of a variety of discrete tectonostratigraphic units of continental platform, rifted margin and oceanic (ophiolitic) origin. It is generally accepted that the relatively autochthonous Tauride platform and the associated thrust sheets restore as a north-facing passive margin during Jurassic–Cretaceous time; however, the Triassic and earlier tectonic setting of the Tauride units is contentious. New data (mainly structural and sedimentological) presented here tests contrasting tectonic models of Late Palaeozoic – Early Mesozoic Tethys ocean evolution. Also, new light is shed on the Late Cretaceous and Early Cenozoic break-up and emplacement of the Tauride units during closure of Tethys. The Late Palaeozoic Tauride stratigraphy consists of shallow-marine carbonate, sandstone and mudstone, characteristic of a proximal passive margin. Detailed stratigraphic logging, facies interpretation, compositional analysis and geochemical evidence supports a passive margin setting, with sediment derived from the Tauride “basement”. Early – Middle Triassic mixed siliciclastic/carbonate sediments are interpreted as representing rifting and subsidence. Late Triassic coarser terrestrial clastics (Cayir Formation) are considered to represent a pulse of rift-related flexural uplift. Sediment provenance during this time was from the underlying Tauride platform to the north of the studied area. A previous hypothesis that a Palaeotethyan ocean closed in this area during latest Triassic “Cimmerian” orogenesis is discounted. Instead, structural and sedimentary data suggest that all of the deformation relates to Late Cretaceous – Early Cenozoic southward emplacement of the Beysehir-Hoyran-Hadim nappes. A first phase of thrusting (thin-skinned) emplaced ophiolite and distal margin units, whilst a second phase (thick-skinned) thrust platform lithologies southwards onto the foreland. Evidence is also summarised, notably from the Palaeozoic – Early Mesozoic Konya Complex to the north, which illustrates the relation of the Tauride platform to other geological terranes in Turkey and elsewhere in the Alpine-Himalayan orogenic belt. This thesis increases understanding of large-scale tectonic and sedimentary processes associated with continental margins and orogenic development.