Akademik Veri Yönetim Sistemi
Journal of Geological Society of India, cilt.101, sa.10, ss.1547-1560, 2025 (SCI-Expanded)
The Central Sakarya Basin (CSB) is a back-arc basin in western Türkiye that formed during the Early Jurassic due to the subduction of the Intra-Pontid Ocean. The Late Cretaceous Vezirhan Formation consists of marine pelagic rocks deposited during the basin’s transgressive phase. This study identifies various soft-sediment deformation structures (SSDS) within the Vezirhan Formation for the first time, which are important for understanding palaeoseismicity and deformation mechanisms. The sedimentological and structural features of the succession were analysed along with SSDS identification to better understand the palaeoenvironment and tectonic-sedimentary processes in the Central Sakarya Basin during the Late Cretaceous. The formation consists of two main sedimentary lithofacies (LF): mud-dominated (LF-1) and debris flow sediment-dominated (LF-2), including lime-mudstones, cherty limestones, radiolarite, and volcanic interlayers with SSDS. The most common deformation structures are slump folds, sedimentary breccias, syn-sedimentary faults, sedimentary dykes and sills, load casts, chaotically deformed strata, and boudin-like structures. The upper section of the complexly deformed strata, where SSDS are found, is often sharply intersected by an erosional surface. This suggests that the deformation occurred during or immediately after the deposition of these deformed layers. The types, sizes, and complex nature of the SSDS indicate a high sedimentation rate, liquefaction-fluidisation processes, and an unstable slope environment. Some deformed layers are interpreted as seismic responses to earthquakes that triggered mass flows linked to active tectonism. Overall, the characteristics of the Vezirhan Formation and the SSDS structures indicate a tectonically active deep-water slope palaeoenvironment in the Central Sakarya Basin during the Late Cretaceous.