Geochemical and mineralogical characteristics of upper cretaceous sediments in the Lok-Karabakh zone (Azerbaijan): implications for provenance, paleoweathering, paleoclimate and reservoir prediction

This study investigates the tectonic setting, sediment provenance, paleoweathering, paleoclimate, and hydrothermal influences on the Upper Cretaceous deposits of the Lok-Karabakh Zone using geochemical and mineralogical data. The results indicate that the sediments were primarily derived from volcanic arc-related mafic to intermediate rocks and deposited in an arc-related basin. Major and trace element analysis suggests that the sediments originated predominantly from volcaniclastic and terrigenous sources. The Chemical Index of Alteration (CIA) values range from 52 to 95, indicating a low to moderate degree of weathering, with most samples reflecting a cold and arid climate. Mineralogical data further support moderate chemical weathering, with montmorillonite as the dominant clay mineral, along with kaolinite, chlorite, and illite. The A-CN-K ternary diagram suggests plagioclase weathering as the dominant alteration pathway, with limited potassium enrichment. Elemental discrimination diagrams confirm a minimal hydrothermal influence, as evidenced by the Al–Fe–Mn ternary diagram and metalliferous index values exceeding 0.4. Tectonic discrimination diagrams reveal that the sediments were deposited in an arc-related basin influenced by subduction-driven processes. The geochemical proxies indicate that the Lok-Karabakh sedimentary basin was characterized by a scarcity of coarse-grained sediments, leading to a predominance of fine-grained, feldspar-rich deposits such as greywackes, which adversely affected reservoir properties. These findings contribute to a better understanding of the geodynamic evolution of the Lok-Karabakh zone during the Late Cretaceous, highlighting the interplay of arc volcanism, climate, and weathering processes in shaping the sedimentary record. Additionally, the results provide insights into sedimentary basin evolution and reservoir potential in similar geological settings. Keywords: Upper Cretaceous, Lok-Karabakh zone; paleoweathering; hydrothermal influence; provenance; tectonic setting.