The Ndembera volcanic rocks are calc-alkaline trachyandesites-dacites-trachytes-rhyolites.
The volcanics are intruded by calc-alkaline I-type granites.
Both the volcanics and granites form a co-genetic suite that was emplaced at 1.89–1.87 Ga.
A similar 1.87 Ga co-magmatic event occurred in the nearby Ubendian belt suggesting a regional thermal event.
The pluto-volcanic suite was generated by crustal anatexis of basic meta-igneous rocks mixed with a minor sedimentary component.