Timing and evolution of structures within the southeastern Greater Caucasus and Kura Fold-Thrust Belt from multiproxy sediment provenance records
Year: 2024
Type: article
Abstract: The Greater Caucasus (GC) mountains are the locus of post-Pliocene shortening within the northcentral 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 associated 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 sandstone petrography, whole-rock geochemistry, and detrital zircon (DZ) U-Pb geochronology. To define source terranes for these sediments, we integrate additional new whole-rock geochemical analyses with published DZ results and geological mapping. Our analysis reveals an apparent discrepancy in up-section changes in provenance from the different methods. Sandstone petrography and geochemistry both indicate a systematic up-section evolution from a volcanic and/or volcani-clastic source, presently exposed as a thin strip along the southeastern GC, to what appears similar to an interior GC source. Contrastingly, DZ geochronology suggests less up-section change. We interpret this apparent discrepancy to reflect the onset of sediment recycling within the KFTB, with the exhumation, weathering, and erosion of early thrust sheets in the KFTB resulting in the selective weathering of unstable mineral species that define the volcaniclastic source but left DZ signatures unmodified. Using the timing of sediment recycling and changes in grain size together as proxies for structural initiation of the central KFTB implies that the thrust belt initiated nearly synchronously along strike at ~2.0–2.2 Ma.
Source: Geosphere
DOI: 10.1130/ges02704.1
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,750
Funder: National Science Foundation
Awards: Collaborative Research: Magnitude and timing of shortening in the Greater Caucasus: Locus of Late Cenozoic Arabia-Eurasia convergence?, Reconciling Invariant Topography with Along-Strike Gradients in Climate and Tectonics in the Greater Caucasus Mountains, Collaborative Research: From subduction to suture: testing collisional stage and lithospheric strength as controls on orogenic structure in the Caucasus, Collaborative Research: A Structural, Thermochronologic, and Provenance Investigation of a Hypothesized Transition From Subduction to Slab Breakoff in the Greater Caucasus
OpenAlex ID: W4403757102