Sedimentological characteristics of the Çukurbag Formation deposited along the Ecemis Fault Zone, Central Anatolia, Turkey
The Oligocene Çukurbag Formation, deposited within a long narrow basin surrounded by the Aladag, Ulukisla, and Nigde metamorphic Groups, consists of conglomerate, sandstone, siltstone, mudstone, marl, mudstone-gypsum successions. A number of analytical methods including morphological, mineralogical, and chemical techniques were employed to investigate the sedimentological characteristics of the formation. According to the grain size analyses, sediments of the formation are very poorly sorted with strong positive to near symmetrical skewness. The analyses show that irregular flow regime should have occurred during sedimentation of the Çukurbag Formation. These sediments comprises mainly of quartz, feldspars, calcite, clinopyroxene, and Fe-oxides. Common clay minerals include smectite, chlorite, and kaolinite. The chemical analyses carried out on the samples representing the bottom to the top of the formation indicated that SiO2, Al2O3, K2O, and P2O5 contents are low compared to the world mudstone averages. However, MgO, CaO, and C contents are comparatively high. Four measured profiles showing the distribution of principle facies within the formation are prepared. Based on the profile analyses, seven distinct lithological facies were distinguished that include massive conglomerate, bedded conglomerate, stratified sandstone, cross-bedded sandstone, laminated siltstone, massive mudstone-marl, and laminated mudstone-gypsum. This study suggests that the sediments of this formation must have been reworked material transported from unknown distances and deposited in an alluvial fan-braided stream and lacustrine environments. © Geol. Soc. India.