Miocene to quaternary volcanism in eastern Kenya: Sequence and geochronology

Pliocene volcano-tectonics and paleogeography of the Turkana Basin, Kenya and Ethiopia

“…Kulal according to Ochieng' et al, 1987), although dates from Asie basalt range from at $2.7 Ma to 0.42 Ma . K/Ar dates from Huri Hills volcanic centers range between 2.3 ± 0.17 and 0.8 ± 0.3 Ma (Brotzu et al, 1984), and ages from Marsabit range from 2.5 ± 0.3 Ma (Nyamweru, 1984) to 0.6 ± 0.2 Ma (Brotzu et al, 1984). These ages overlap considerably, but volcanism at Asie, Huri Hills and Marsabit continued following the cessation of volcanism at Kulal; which may have shifted to Longipi volcano located between Kulal and the south basin of Lake Turkana (Fig.…”

Pyroxenite xenoliths from Marsabit (Northern Kenya): evidence for different magmatic events in the lithospheric mantle and interaction between peridotite and pyroxenite

“…The occurrence of deformed cumulates from alkaline melts can be explained by the long-time magmatic activity in the region of Marsabit, starting in Mesozoic-Paleogene times (i.e., diabase intrusion associated with the development of the Anza Graben; Winn et al 1993;Morley et al 2006), until the development of the Marsabit shield volcano. The xenolith-bearing basanites and alkali basalts represent the youngest volcanic products (1.8-0.5 Ma; Brotzu et al 1984;Key et al 1987) and thus potentially sampled mafic lithologies accumulated earlier. The presence of such material is supported by seismic studies providing evidence for presence of mafic material underplating the lowermost crust beneath the rift flanks of the Kenya rift (Mechie et al 1997) and by the occurrence of pyroxenite xenoliths in South Ethiopian basanites interpreted to have formed during Quaternary alkaline magmatic activity (Orlando et al 2006).…”

Mount Kenya volcanic activity and the Late Cenozoic landscape reorganisation in the upper Tana fluvial system

“…The Nyambeni Mountain Range was initiated at the same time as Mt Kenya, but its activity continued into sub-recent times Olago et al, 2000). Nyambeni eruptions took place between 4.5 and 0.5 Ma K/Ar (Brotzu et al, 1984) but the range is still considered active and includes a set of parasitic cones on the Mt Kenya slopes along a roughly SW-NE lineament which has dated eruptions from the Holocene (Mahaney, 1989;Olago et al, 1999Olago et al, , 2000.…”