Zircon petrochronology of Upper Devonian–Lower Carboniferous sandstones from Armenia: New insights into the evolution of the northeastern margin of Gondwana

Zircon petrochronology provides key insights into the sedimentary evolution of ancient terranes. We analyzed ∼470 detrital zircons from two Upper Frasnian–Lower Famennian and one Upper Famennian–Visean sections of the South Armenian Block (SAB) using U–Pb geochronology, Lu–Hf and O isotopes, and trace-element geochemistry. These successions document the final episodes of siliciclastic deposition along northeastern Gondwana. All sandstones are highly quartz-rich (>90%), reflecting long-distance transport. About 350 concordant U–Pb ages define older clusters (∼19%), Neoproterozoic (∼63%), and Paleozoic (18%), with peaks at ∼2.5 Ga, ∼910 Ma, ∼600 Ma, and ∼350 Ma, consistent with eastern Gondwanan provenance. Zircon ɛHf(t) (up to –30) and δ 18 O data (up to 12) for the 600–500 Ma and 900–700 Ma groups indicate derivation from highly evolved sources. Trace-element proxies (U/Yb, LREE/HREE, Ce/Y) display bell-shaped distributions peaking at 700–500 Ma, further pointing to a mixture of evolved and mildly juvenile sources. Zircon petrochronological constraints suggest that the main contributors were likely the sedimentary cover of the Arabian–Nubian Shield, supplemented by more distal Pan-African basement domains such as the Saharan Metacraton and Mozambique Belt. A relative scarcity of 600–500 Ma age zircons, together with recycled ɛHf(t) values, indicates only minor input from the Cadomian arc. The increase in zircon ɛHf(t), together with the marked decrease in U/Yb, LREE/HREE, and Ce/Y after 500 Ma, indicates a shift toward more oceanic-like geochemical signatures, reflecting attenuation of the continental contribution during the early rifting of northern Gondwana terranes. Taken together, the high maturity, peripheral Gondwanan setting, stratigraphic facies, age spectra, and isotopic signatures of the SAB sandstones support their interpretation as very distal representatives of the eastern Gondwana super-fan system.