A Fossil Morphology: The Miocene Fluvial Network of the Western Taurus (Turkey)
Résumé
In Southern Turkey, east of Antalya, the Taurus chain contains traces of several fossil valleys incised into the most karstic areas of a high surface (1500–2200 m). These streamless valleys exhibit meanders and dry tributaries that are fragments of a former network directed NE-SW, at right angles to the structures of the Taurus chain. All these disconnected landforms are older than the Quaternary tectonic uplift of the chain. This older age is pointed out not only by a difference in orientation between the fossil network and the present drainage (which is not yet fully organised), but also by morphological contrasts between the fossil (wide valleys remnants) and recent (deeply incised rivers in narrow gorges) networks. At lower altitudes in the same area, Miocene conglomerates in the Manavgat Basin contain pebbles that can be confidently traced back to their source areas, owing to their distinctive lithologies. The study of the distribution and content of these conglomerates indicate a detrital origin located inland towards Central Anatolia where specific outcrops are located. While the fossil river network evidenced on the uppermost surfaces of the chain answers the question of how this detrital material could have travelled about eighty kilometres through the Taurus calcareous units, the age of the conglomerates allows dating the uplifted fossil valleys back to the Early Miocene.