Gypsum Karst Landscape in the Sivas Basin

Abstract

The Tertiary Sivas Basin, Central Anatolia, includes one of the most outstanding gypsum karst terrains in the world, covering an area of 2140 km2. This gypsum karst significantly contributes to enrich the diversity of karst landscapes in Turkey and constitutes an excellent natural laboratory for understanding their evolution because it develops and degrades much faster than carbonate karst landscapes. The ENE–WSW trending Sivas gypsum karst terrain is 280 km long and 55 km wide. The karst landscapes are mainly developed on Oligocene gypsum deposits. Sivas gypsum karst terrain has a wide variety of well-developed karst features such as karren, different types of dolines (solution, collapse and suffosion), blind valleys, karst springs, swallow holes (ponors), karstified paleo-valleys, caves, unroofed caves, natural bridges, gorges, uvalas and poljes. Solution dolines, which riddle a large part of the area, are the most common landform. The Kızılırmak River and its tributaries drain the Sivas Basin. Therefore, Quaternary evolution of the Kızılırmak River has played an important role in the long-term evolution of the karst landscape in the basin. Karst development in some parts of the basin has also been affected by halokinetic structures.