Akademik Veri Yönetim Sistemi
Lithos, cilt.532-533, 2026 (SCI-Expanded, Scopus)
Understanding melt source evolution during arc–back-arc magmatism is essential for resolving crustal growth processes and the development of felsic-hosted volcanogenic massive sulfide (VMS) systems. Here we integrate new zircon Hf-O isotope data with published geochronological and whole-rock geochemical datasets to reassess the petrogenesis of Late Cretaceous arc and back-arc magmatic flare-ups in the eastern Sakarya Zone (ESZ), NE Türkiye. Two high-flux magmatic episodes are recognized: a Turonian–Santonian pulse (∼92–86 Ma) forming the lower volcanic sequence (LVS), and a younger Campanian pulse (∼84–75 Ma) forming the upper volcanic sequence (UVS), accompanied by contemporaneous arc-related granitoids. Zircons from both LVS and UVS display predominantly positive εHf(t) values (+2 to +12) coupled with mantle-like δ18O (5.0–5.6‰), but contain abundant inherited Mesoproterozoic–Paleozoic cores and show variable two-stage model ages (TDMC = 0.4–1.4 Ga). Together with the peraluminous affinity of many felsic units, these features indicate that the dacite–rhyolite suites hosting VMS deposits were generated by melting of compositionally heterogeneous lower crust variably hybridized by juvenile basaltic inputs. Arc granitoids likewise record a transition from dominantly juvenile, I-type magmatism during the Coniacian–Santonian to more evolved, crust-influenced signatures during the Campanian. We propose that both flare-ups reflect repeated episodes of basaltic underplating and deep-crustal heating, producing voluminous felsic magmas capable of sustaining long-lived hydrothermal systems. The spatial and temporal coincidence between felsic-dominated flare-ups and VMS mineralization suggests that hybridized felsic magmas, rather than purely juvenile mantle melts, played a central role in generating the physiochemical conditions required for metal-bearing hydrothermal fluids in the ESZ.