The multidisciplinary approaches on facies developments and depositional systems of the Bahcecik travertines, Gumushane, NE-Turkey

Abstract

The Bahcecik travertines, located in Gumushane (NE-Turkey) have been investigated for the first time using a multidisciplinary approach, which included sedimentological (lithofacies, depositional system), petrographic, radiometric Th-230 dating, geochemical analysis (stable isotopes), palynomorphs and geophysics (GPR). A carbonate build-up, 12 m thick, was formed with some interruptions, through the middle Pleistocene period. For this study, two travertine sections (F and D) were extensively used to figure out palaeoenvironmental and palaeoclimatic proxies. The main precipitation cycles, separated by palaeosol levels, have been described and interpreted from a sedimentological perspective. The carbonate deposits consist of shrubs, crystalline crust, reed, laminated (micritic), pisoids, oncoids, calcite thin rafts and coated gas bubbles, lithoclasts, and palaeosol levels. The sedimentological fieldwork and petrographic analysis show that the Bahcecik travertines formed in depression depositional and slope depositional systems. Moreover, the first Th-230 ages, stable isotopic results and palynofloral data in this study, prove that the Bahcecik travertines might have been affected by climatic and tectonic interruptions. According to dating results, the travertine occurrences began to precipitate during the 353 ka and continued into the 263 ka. Based on the palynological data, an abundance of herbaceous plants species was recorded in the warming period of climate. The thickness ranges from 2 to 12 m of the Bahcecik travertines. This precise thickness and also the presence of two different travertine formations, separated by a palaeosol erosional surface, were recorded by the ground penetrating radar (GPR) geophysical method.