Petrogenesis and tectonic setting of the Pan-African Deng-Deng intrusive complex in the Lom series, Eastern Cameroon

The Deng-Deng intrusive complex belongs to the Central African Fold Belt (CAFB) in eastern Cameroon and includes granodiorite and diorite. Both rocks are classified as metaluminous to slightly peraluminous, high-K calc-alkaline, and I-type granitoids (A/CNK <1.1). Primitive mantle-normalized trace-element patterns display large-ion lithophile elements (LILE) enrichment, such as Rb, Cs, Ba and K, and depletion in high-field-strength elements (HFSEs), such as Nb, Ti, Ta and P. The studied rocks are enriched in LREEs relative to HREEs and exhibit weak negative Eu anomalies (Eu/Eu* = 0.61-0.92 and 0.59-0.67 for the granodiorite and diorite, respectively), suggesting active continental margin arc affinity. The emplacement temperatures of these granitoids are estimated between 775 and 806 degrees C. Combined with their diagnostic ratios (e.g., Th/Ta, Rb/Sr, Nb/La, and La/Sm), we propose that the Deng-Deng granitoids were sourced by mixing between mafic magma derived from the lithospheric mantle and felsic magma derived from partial melting of a lower crust in a convergent margin setting.