Kerimasi Volcano, also known as Kerimasi (''Mlima Kerimasi'', in

Swahili Swahili may refer to: * Swahili language, a Bantu language official in Kenya, Tanzania and Uganda and widely spoken in the African Great Lakes * Swahili people, an ethnic group in East Africa * Swahili culture Swahili culture is the culture of ...

) at is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

located in Monduli District of Arusha Region in Tanzania. The majority of the mountain lies in Engaruka Ward, and a quarter of it is in the Ngorongoro Conservation Area. The volcano is located in the geographic area known as the

Crater Highlands The Crater Highlands (Ngorongoro Highlands) are a geological region along the East African Rift in the Arusha Region and parts of northern Manyara Region in north Tanzania. Geology The highlands are located in a spreading zone at the intersec ...

and is a shield volcano that last erupted in the Pleistocene.

Geology and Mineral composition

Kerimasi, an extinct nephelinite volcano in northern Tanzania's eastern rift valley, emitted carbonatite tephra during its final eruptive phase. The tephra was primarily composed of alkali carbonatite, making it the earliest well-documented example of premodern natrocarbonatite volcanism. The main carbonate mineral was nyerereite, which is also the major mineral in present natrocarbonatite lava flows from the neighboring volcano

Oldoinyo Lengai Ol Doinyo Lengai (Oldoinyo Lengai), "Mountain of God" in the Maasai language, is an active volcano located in the Gregory Rift, south of Lake Natron within the Arusha Region of Tanzania, Africa. Part of the volcanic system of the East African R ...

. Kerimasi's nyerereite was leached of its alkalis by meteoric water, and it is currently represented by

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

pseudomorphs.Richard L. Hay; Natrocarbonatite tephra of Kerimasi volcano, Tanzania. Geology 1983;; 11 (10): 599–602. doi: https://doi.org/10.1130/0091-7613(1983)11<599:NTOKVT>2.0.CO;2

References

Volcanoes of Tanzania Geography of Arusha Region Pleistocene shield volcanoes {{Arusha-geo-stub