Geodynamic Evolution of the Northern Pan-African Belt Revealed by Petrography and Geochemistry of the Laddé-Goré Granitoids

The Laddé-Goré granitoids, located in the northern Pan-African Belt of Cameroon, comprise a compositionally and mineralogically diverse suite of plutonic rocks that offers key insights into the magmatic and tectonic evolution of Central Africa during the Neoproterozoic. This study integrates petrographic observations with major and trace element geochemistry, as well as REE patterns, to decipher their petrogenesis and geodynamic setting. The suite includes amphibole-bearing granites, amphibole-biotite-muscovite granites, muscovite leucogranites, and quartz diorites. Whole-rock analyses show SiO2 contents ranging from 63.9 to 71.2 wt%, with high K2O + Na2O (7.2–8.6 wt%) and metaluminous to weakly peraluminous signatures (A/CNK = 0.97–1.04). The rocks display magnesian affinities, and high-K calc-alkaline to shoshonitic trends. Trace element data reveal high contents of LILEs (Rb = 45–147 ppm, Ba = 1090–2458 ppm), moderate REE enrichment (La = 20.8–168 ppm, Ce = 34.2–346 ppm), and negative anomalies in Nb, Ta, Ti, and P, suggesting derivation from a subduction-modified source. Eu anomalies (Eu/Eu* = 0.36–1.85) and fractionation indices (La/Yb)N = 19.4–41.1; (Gd/Lu)N = 2.1–4.4) imply variable degrees of plagioclase and amphibole fractionation. Geochemical modeling supports magma generation from a metasomatized lithospheric mantle, followed by fractional crystallization and limited crustal assimilation. The granitoids evolved in a transitional setting between an active continental margin and early post-collisional extension. Comparative data from Pan-African suites in Nigeria, Sudan, and northeastern Brazil further confirm that Laddé-Goré magmatism is part of a broader crust–mantle interaction regime during the final stages of Gondwana assembly. The associated enrichments in Sn (Nb = 12-32ppm; Ta = 0.5-1.3ppm; W = 0.5ppm) suggest potential for specialized mineralization.