Geodynamic record of Rodinia breakup to Gondwana formation: Insights from bulk geochemistry, whole-rock Sr-Nd isotopes, and zircon U-Pb-Hf data of Katherina Ring Complex, Sinai Peninsula, Egypt

Abstract

• Precise timing of Precambrian tectonism (∼755 to 594 Ma) for the Northern Arabian-Nubian Shield. • Four phases of Neoproterozoic granitoids are identified in the Katerina Ring Complex, Sinai, Egypt. • First detection of the earliest magmatism (∼755 Ma) linked to Mozambique Ocean closure in Sinai. • Wadi Rofaiyed plutons exhibit diagnostic signatures of continental adakitic granitoids. The Arabian-Nubian Shield (ANS) serves as a key geological archive, preserving the tectono-thermal evolution associated with the Rodinia breakup (∼900–800 Ma) and Gondwana formation (∼800–620 Ma). The Katherina Ring Complex (KRC), located in the Sinai Peninsula, Egypt (northern ANS), exemplifies continental growth through multistage magmatism and orogenesis, spanning the Tonian to Ediacaran periods (∼900–530 Ma). Despite its importance, debates persist regarding the nature, age, crustal characteristics, and magma source evolution of its constituent units. Situated in the northwestern part of the KRC, the Wadi Rofaiyed Cu deposit offers an exceptional natural laboratory for investigating continental crust formation during this interval, owing to its superb exposure and preservation. This study integrates detailed fieldwork, petrographic analyses, whole-rock geochemistry, Sr-Nd isotopes, and in situ zircon U-Pb-Lu-Hf isotopic data. It aims to (i) establish a robust chronological framework for the unmetamorphosed plutonic rocks of the KRC, (ii) advance the understanding of associated geodynamic processes, and (iii) elucidate the episodic magmatism events. The findings show that Wadi Rofaiyed juvenile crust developed in four main phases: (i) a subduction-accretionary phase (∼755 Ma) characterized by intense calc-alkaline magmatism, originating from the partial melting of mafic lower crust; (ii) a syn -collisional phase (∼630 Ma) occurred during the collision between the Saharan metacraton and the younger ANS crust, producing I-type granitoids formed through magma mixing and crustal anatexis; (iii) a post-collisional phase characterized by intermediate I-type (∼595 Ma) to felsic A-type alkaline magma (∼594 Ma), originated from the partial melting of the overthickened lower crust corresponding to lithospheric delamination; and (iv) an anorogenic phase (∼530 Ma) related to the final amalgamation of Greater Gondwana. Isotopic analyses across all four magmatic phases reveal low initial 87 Sr/ 86 Sr (0.702648 to 0.703311) and positive ε Hf ( t ) (+2.84 to +7.78) and ε Nd ( t ) (+2.61 to +5.21) values, consistent with lower crustal sources with depleted mantle-like signatures. The model ages ( T DM2 ) for these magmatic rocks derived from zircon Hf (1.2–1.5 Ga) and whole-rock Nd isotopes (0.96–1.17 Ga) support a predominantly juvenile crustal origin. These findings underscore the multistage tectono-magmatic evolution of the northern ANS, advancing our understanding of obduction-accretion dynamics and crustal development during the Neoproterozoic.