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Surface ruptures associated to the July–August 2007 Gelai volcano-tectonic event, North Tanzania. Journal of Petrology, 36, 797–826.ĭelvaux, D., Smets, B., Wauthier, C., Macheyeki, A. Petrology and mineral chemistry of plutonic igneous xenoliths from the carbonatite volcano, Oldoinyo Lengai, Tanzania. Keller (Eds.), Carbonatite volcanism (pp. Petrology and geochemistry of Oldoinyo Lengai lavas extruded in November 1988: Magma source, ascent, and crystallization. Bulletin of Volcanologique, 33, 791–8172.ĭawson, J. The Engaruka-Natron explosion crater area, northern Tanzania. Contribution to Bulletin of the Global Volcanism Network, 32, 14–15.ĭawson, J. Geological Society London Memoir.ĭawson, J. The Gregory Rift Valley and Neogene-recent volcanoes of northern Tanzania (Vol. Bulletin of Volcanologique, 27, 81–92.ĭawson, J. Carbonatitic volcanic ashes in northern Tanganyika.

Bulletin of Volcanologique, 24, 349–387.ĭawson, J. Sodium carbonatite lavas from Oldoinyo Lengai, northern Tanganyika. , and also to aircraft as ash columns may attain heights of tens of kilometres. Lengai presents a potential hazard to the local Maasai who live in the proximity of Lake Natron Lengai erupts on average every 15–20 yr, although some of the recent eruptions have been of nephelinite rather than natrocarbonatite. This feature overflowed and collapsed during violent eruptions between 2007–2008 and the new crater is too deep and unstable to enter. Flows of natrocarbonatite associated with eruptions from the early 1990s could formerly be observed in a shallow summit crater which had remained intact since 1960. The altered, white or pale grey natrocarbonatite ashes that partially cloak the upper slopes resemble an ice cap when seen from distance. The high sodium contant of the natrocarbonatitite lavas and ashes reacts rapidly with meteoric waters to create secondary, white coloured minerals within a few days. The natrocarbonatite is erupted at temperatures considerably lower than silicate lavas. Silicate magmas are the most abundant, but it is the highly unusual natrocarbonatite magmas for which Lengai is so well known. Oldoinyo Lengai is one of the most famous Holocene volcanoes on Earth as it was here the coexistence of two immiscible magmas with radically different compositions was first observed in nature. (3,188 m) rises some 2.5 km above the valley floor to the southwest of Lake Natron. Natron is an extraordinarily toxic, soda lake (pH of 12) with extensive sodium carbonate salt flats. The lake is bordered to the west by the Western Escarpment, a major rampart constructed of layer upon layer of Pliocene-age volcanic lavas and tephra, and to the east by the giant Gelai

Is located in a desolate, relatively low-lying section of the Gregory Rift Valley, northern Tanzania.