Crustal evolution and stabilization of the Arabian-Nubian Shield: Constraints from whole-rock Sr Nd and zircon U-Pb-Hf-O isotopes of bimodal volcanics

The Neoproterozoic Arabian-Nubian Shield (ANS) is one of the largest juvenile crustal provinces on Earth, providing a natural laboratory for investigating the processes of continental crust formation and stabilization. Although arc accretion is widely regarded as a key mechanism of crustal growth in the ANS, the subsequent transformation of juvenile terranes into stable continental lithosphere remains poorly constrained. Here, we present integrated geochemical, Sr Nd isotopic, and in-situ zircon U–Pb–Hf–O data from the Ranga volcanic suite to evaluate the tectono-magmatic evolution of the late Neoproterozoic ANS. The Ranga volcanic rocks are bimodal with a tholeiitic affinity and yield a crystallization age of ~585 Ma. The mafic rocks are characterized by low SiO 2 (49.8–54.1 wt%), high MgO (5.9–9.4 wt%), a negligible Eu anomaly (1.05–1.22), low initial 87 Sr/ 86 Sr ratios (0.702829–0.703946), and positive εNd(t) (+6.39 to +7.84), indicate that the mafic rocks formed through fractional crystallization of melts derived from a juvenile depleted source. The felsic rocks display high SiO 2 (72.5–78.9 wt%), low MgO (0.3–1.4 wt%), a negative Eu anomaly (0.50–0.79), low initial 87 Sr/ 86 Sr ratios (0.702994–0.703364), positive εNd(t) (+5.94 to +7.13), zircon εHf(t) (+7.38 to +15.14) values, and zircon δ 18 O signatures (4.37–6.18 ‰), consistent with partial melting of hydrothermally altered, MORB-like lithosphere. These results highlight juvenile magmatism and reworking of pre-existing juvenile crust as key drivers in the stabilization and maturation of juvenile crust within the ANS. Collectively, these data define an autogenic, two-step pathway in which juvenile arc addition is followed by intracrustal melting to yield felsic additions converting juvenile provinces into stable continents, a process likely widespread across accretionary orogens.