stripes
Gboko Hill, situated about 2 km northwest of Gboko, and Ikyuen Hill, lying some 15 km to the east of that town, are rhyolite domes that intrude Precambrian basement rocks (Umeji and Caen-Vachette, 1983). According to Baudin et al. (1988) the rhyolites contain riebeckite, but no other information has been located.
BAUDIN, P., POPOFF, M. and COULON, C. 1988. Mesozoic magmatism of the southern part of the Benue Trough (Nigeria). Mesozoic to present-day magmatism of the African Plate and its structural setting. PICG-IGCP 227 Workshop, Giens, France. International Center for Training and Exchanges in the Geosciences, Abstracts, 34-6.UMEJI, A.C. and CAEN-VACHETTE, M. 1983. Rb-Sr isochron from Gboko and Ikyuen rhyolites and its implications for the age and evolution of the Benue Trough, Nigeria. Geological Magazine, 120: 529-33.