Petrogenesis and Geodynamic Significance of the Younger Granites of the Jos Plateau: New Isotopic and Geochemical Evidence

The Jurassic Younger Granites of the Jos Plateau, North Central Nigeria, represent one of Africa's most distinctive anorogenic ring complex provinces, but unresolved debates regarding their mantle versus crustal source, the role of lithospheric extension versus plume activity, and their correlation with contemporaneous magmatic events elsewhere in the West African Craton limit their utility as tectonic probes of Mesozoic geodynamics. This study reinvestigates the petrogenesis and geodynamic significance of the Jos Plateau Younger Granites through comprehensive new isotopic and geochemical data from eight previously unsampled ring complexes. In-situ zircon U-Pb dating by laser ablation inductively coupled plasma mass spectrometry provides high-precision emplacement ages for each complex, establishing the duration and progression of magmatic activity. Whole-rock major and trace element geochemistry is combined with Sr-Nd-Pb-Hf isotope data to fingerprint mantle source characteristics and quantify crustal contamination. Zircon oxygen and hafnium isotope compositions measured in-situ provide complementary constraints on source heterogeneity. The compiled dataset is evaluated using petrogenetic modelling of fractional crystallisation and partial melting to reconstruct source compositions. The study tests competing geodynamic models including lithospheric delamination, mantle plume activity, and post-collisional extension against the derived geochemical and geochronological constraints. An original petrogenetic model is proposed that reconciles the unusual A-type granitic compositions with a lithospheric delamination trigger. Keywords: Younger Granites, Jos Plateau, petrogenesis, A-type granite, isotope geochemistry.