Geodynamic and paleogeographic settings of the Upper Cretaceous terrigenous successions, northeastern slope of the Lesser Caucasus: Geochemical and mineralogical constraints

The geochemical signatures of clastic sedimentary sequences are determined by the parent rocks, weathering intensity, and the complex processes of transport and deposition. These variables define the mineralogical and chemical attributes of the basin fill, offering significant insights into the prevailing geodynamic settings and paleoclimatic conditions. The Upper Cretaceous deposits in the Lesser Caucasus are widely distributed and represent a vital geological archive for studying the region’s history. To reconstruct the paleogeographic and depositional conditions of the northeastern slope of the Lesser Caucasus, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was employed for high-precision elemental analysis, while X-ray diffraction (XRD) was utilized to determine the mineralogical composition of the sequences. The terrigenous sequences of the region comprise the diverse lithological assemblages, primarily categorized as shales, iron-rich shales (Fe-shales), and greywackes. These rocks exhibit low compositional and mineralogical maturity, indicating accumulation in high-energy environments with a significant influx of fresh volcaniclastic material. Geochemical proxies for chemical weathering reveal a transition from intensive to moderate alteration. This low maturity is further substantiated by the preservation of primary silicates, which is characteristic of rapid sediment burial. Elemental analysis indicates that the detrital material was predominantly derived from first-cycle mafic and ultramafic magmatic sources, reflecting the significant erosion of ophiolitic and associated sequences. Geochemical indicators confirm a first-cycle sedimentary regime with minimal recycling and limited hydraulic sorting. Tectonic discrimination functions identify an oceanic island arc setting, where volcaniclastic and terrigenous debris accumulated in basins governed by active subduction and convergence processes. These findings are consistent with semi-humid and semi-arid paleoclimatic conditions that prevailed during the Late Cretaceous. Collectively, these indicators elucidate the geodynamic setting of the region and emphasize the interplay between arc volcanism and the regional tectonic framework in shaping the Mesozoic sedimentary record.