Climatic and tectonic effects on the origin and evolution of the Dereiçi travertines (the Başkale Basin, Eastern Türkiye), and neotectonic implications

The Başkale Basin is located in the easternmost part of Türkiye, within a tectonically active area, and located at the intersection of Europe, Asia and the Middle East. In this study, the Dereiçi travertines, one of the most important products of neotectonism in the basin, were investigated sedimentologically, mineralogically and geochemically. To understand the neotectonic evolution of the travertine succession, the sequence was studied from bottom to top as regards morphology, lithofacies and U/Th dates. Crystalline crust, coated gas bubbles, shrub, paper-thin raft and palaeosol lithofacies have been detected in the Dereiçi travertines, which are morphologically of layer type, two ridge types and terrace type. The Dereiçi travertines commenced to precipitate at the intersection of the Işıklı and Ilıcak faults at 255.56 ±9.01 ka, and their deposition continues today. Travertine deposition paused twice between 198.31 ±18–143.07 ±1.5 ka and 96.73 ±8.34–61.59 ±5.4 ka, when palaeosol development took place. According to field and laboratory studies, the Dereiçi travertines developed under climate and tectonic control. The Işıklı and Ilıcak faults played active roles in the development of the travertines. As the travertine ages are linked to movement on both faults, the age of the Işıklı Fault should be 255.56 ±9.01 ka or earlier, and that of the Ilıcak Fault should be 143.07 ±1.5 ka or earlier.