Remnants of Cretaceous volcanic rocks are preserved in a collar along the western and southern margins of the massif. Their angle of dip increases towards the contact where clasts of country rock occur within the granite forming a magmatic breccia. The origins of the magmas that formed the Brandberg intrusion are related to emplacement of mantle-derived basaltic magma during continental break-up which led to partial melting of crustal rocks resulting in a hybrid granitic magma.
Cretaceous volcanic rock remnants persist in a ring along the western and southern periphery of the massif. Their orientation increases towards the boundary where clasts from the surrounding rock are embedded within the granite, creating a magmatic breccia. The origins of the Brandberg intrusion's magma are linked to the insertion of mantle-derived basaltic magma during continental rifting, leading to partial melting of crustal rocks and forming a hybrid granitic magma.