This study examines the paleoweathering conditions, provenance, and tectonic setting of Neocomian deposits, focusing on the Kepuch and Gyrkhbulag Formations within the Vandam tectonic zone on the northern flank of the South-Caucasian microplate, characterized by complex Cretaceous flysch and volcanogenic formations. By integrating petrographic and geochemical data, this research aims to identify distinctive geochemical features reflecting provenance, weathering processes, and depositional environments, deepening the understanding of the regional geodynamic evolution. Petrographic analysis of the sandstones reveals a composition primarily consisting of rock fragments, quartz, and feldspar, with a significant clay matrix exceeding 15%, classifying them as lithic wackes and highlighting the dominance of volcanic and metamorphic rock fragments along with authigenic calcite cement. All geochemical proxies for paleoweathering, such as the Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA), suggest that the source regions underwent a low to moderate degree of weathering. Provenance analysis suggests that the sediments are derived from a mixed source, primarily consisting of felsic and intermediate igneous rocks, consistent with a continental island arc tectonic environment. Discrimination diagrams – including SiO₂ versus K₂O/Na₂O, Al₂O₃/SiO₂ versus Fe₂O₃+MgO, La–Th–Sc, Ti/Zr versus La/Sc, and Eu/Eu*–Gd_N/Yb_N – place the samples within active continental margin and continental island arc fields, supporting a subduction-related sediment source. This analysis highlights the significant role of tectonic processes in shaping the geochemical characteristics of these siliciclastic rocks.

Keywords: provenance, tectonic setting, paleoweathering, Vandam zone, Kepuch and Gyrkhbulag Formations

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