Timing and Evolution of Structures within the Southeastern Greater Caucasus and Kura Fold-Thrust Belt from Multiproxy Sediment Provenance Records

The west-northwest trending Greater Caucasus (GC) mountains locally represent the main locus of post-Pliocene shortening within the north central Arabia-Eurasia collision. Although recent low-temperature thermochronology constrains the timing of orogen formation, the evolution of major structures remains enigmatic - particularly regarding the internal kinematics within this young orogen and the Kura Fold-Thrust Belt (KFTB), which flanks its southeastern margin. Here we use a multiproxy provenance analysis to investigate the tectonic history of both the southeastern GC and KFTB by presenting new data from a suite of sandstone samples from the KFTB, including point counts, whole-rock geochemistry, and detrital zircon (DZ) U-Pb geochronology. To define source terrains for these sediments, we integrate additional new whole-rock geochemical analyses with published DZ results and geological mapping. Our analysis reveals a progressive change up-section from a dominantly volcanic or volcaniclastic source, presently exposed as a thin strip along the southeastern GC, to a flysch source, now exposed in the core of the GC. In detail, while point counts and geochemistry suggest a consistent history of changing sediment sources, more limited DZ geochronology suggests less up-section change. We interpret this apparent discrepancy to reflect the onset of sediment recycling and local reworking of sediments within the KFTB, selectively weathering unstable mineral species that define the volcaniclastic source terrain. We conclude that this transition constrains the timing of the initiation of the central KFTB, which we argue initiated nearly synchronously along-strike.