Petrogenesis and Tectonomagmatic Evolution of the Neoproterozoic Jabal Sayid Metavolcanic Rocks, Arabian Shield, Saudi Arabia: Implications for Arc Magmatism and VMS Mineralization

The Jabal Sayid metavolcanic succession in the western Arabian Shield records Neoproterozoic arc magmatism and hosts a major VMS Cu-Zn-Au deposit in Saudi Arabia. This study investigates 31 volcanic samples, ranging from basalt to rhyolite, using petrography and whole-rock geochemistry to evaluate their petrogenesis, evolution, tectonic setting and metallogenic significance. The studied rocks belong to a subalkaline, calc-alkaline suite and show geochemical features typical of a subduction-related volcanic arc, including LREE enrichment, negative Eu and Nb anomalies, and LILE enrichment. Magma evolution was primarily controlled by the fractional crystallization of amphibole, clinopyroxene, plagioclase, and Fe–Ti oxides, although potential contributions from crustal interaction and/or crustal partial melting cannot be excluded. Widespread chloritic, sericitic, silicic, epidotic, and carbonate alteration reflects prolonged hydrothermal activity associated with felsic volcanism and favorable for VMS mineralization. These outcomes indicate that the Jabal Sayid succession formed within a juvenile Neoproterozoic volcanic arc and provide useful geochemical indicators for VMS exploration across the Arabian-Nubian Shield.