A 35km diameter polygonal ring complex.
The complex covers an approximate area of some 418km2.

This region forms a roughly triangular area of about 622 km2, with approximately 183 km2 underlain by units of alkaline granite. The Complex is notable for its mineralization and contains economically valuable minerals, such as tin and columbite.

Encircling the Ropp Complex is an arcuate and polygonal ring dyke that encompasses a basement and a prominent central massif of rugged younger granite hills. Some of these central hills rise over 300 m above the plateau, creating prominent landmarks. The Ropp Complex features distinct volcanic and plutonic cycles. The granitic intrusion cycle began with coarse-grained granite porphyry, akin to the Jos-Bukuru Complex, followed by a series of biotite and riebeckite granites. Later stages included recurring granite porphyry, hornblende–biotite granite, and late biotite granites. The volcanic cycle comprises quartz porphyries, rhyolites and explosion breccias, and early basic dykes.

The Ropp Complex predominantly consists of biotite granite along with minor albite arfvedsonite granites, which occasionally show rare metal Nb-Sn mineralization. The biotite granite in Bukka Bakwai village holds the highest primary columbite, while the Ropp biotite granites rank second in tin production after the Jos-Bukuru biotite granites. The Ropp alkaline A-type granites have coeval intrusive ages ranging from 161.1 ± 1.7 Ma to 162.3 ± 5.1 Ma, with chemical characteristics indicative of alkaline ferroan granites.

Other Regions, Features and Areas containing this locality

References