Facies Evolution and Lake-Type Variability Related to Climatic Cycles in the Late Triassic Çakrazboz Formation, Western Pontides, Türkiye

Authors : Gül Şen, İsmail Ömer Yılmaz

Pages : 121-168

Doi:10.25288/tjb.1765110

View : 88 | Download : 188

Publication Date : 2026-01-13

Article Type : Research Paper

Abstract :The Çakrazboz Formation, located in the Amasra–Kastamonu region of the Western Pontides (NW Türkiye), represents the only known Triassic continental sedimentary succession in Türkiye. This study integrates sedimentological, petrographic, and stratigraphic data from six measured sections to reconstruct depositional environments and evaluate paleoclimatic controls. Field and thin-section analyses reveal a complex facies mosaic comprising three major lithofacies groups: lacustrine, palustrine, and fluvial. Lacustrine facies are represented by carbonate-rich successions, including micrite, wackestone, and packstone, indicating low-energy profundal to sublittoral settings. Palustrine facies, occurring predominantly in marginal lake environments, are characterized by pedogenic overprinting, fenestral fabrics, root traces, and desiccation features, with the Bozköy and Başköy-1 sections showing more pronounced development of these features. Başköy-2 and Başköy-3 exhibit fluvial point-bar deposits with upward-fining successions and pedogenically modified mudstones, representing meandering river systems deposited during overfilled lake stages. Stratigraphic and sedimentological evidence indicates that the basin experienced repeated shifts between underfilled, balanced-fill, and overfilled lake stages. Carbonate-rich successions in the Çakrazboz and lower İncigez sections represent low-energy profundal lacustrine conditions typical of underfilled stages. The upper İncigez and Başköy-1 sections preserve features of balanced-fill conditions, with fining-upward transgressive intervals overlain by progradational littoral facies. Overfilled conditions are locally recorded in Bozköy and in the upper parts of Başköy-1, as evidenced by laterally extensive successions that thicken and coarsen upward, reflecting sustained freshwater inflow. These vertical facies transitions, stacking patterns, and diagenetic overprints are indicative of orbitally forced lake-level fluctuations under subhumid to semi-arid climate regimes, contributing to a broader understanding of Late Triassic continental basin evolution, facies architecture, and climate-controlled sedimentation.
Keywords : Fasiyes evrimi, Göl tipi değişkenliği, Yörüngesel döngüler, Çakrazboz Formasyonu, Batı Pontidler, paleoiklim

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