The Ituwa Surge deposits of the Holocene Ngozi caldera, Mbeya Region, Tanzania
The Ituwa Surge deposits belong to the Holocene Ngozi volcano (volcano number 222164 of the Smithsonian Institute Global Volcanism Program; Siebert et al. 2010) of the Rungwe Volcanic Province (RVP; Harkin 1960; Lenhardt and Oppenheimer 2014). They are named after their type locality and place of best exposure, the village of Ituwa in the Mbeya Region of southwestern Tanzania. Volcanism within the RVP started approximately 9 Ma ago and can be divided into a Late Miocene (~9.2–5.4 Ma), a Late Pliocene-Early Pleistocene (~3–1.6 Ma) and a Mid-Pleistocene-recent (<~0.6 Ma) phase (Ebinger et al. 1989, 1993; Ivanov et al. 1999).
The trachytic-to-phonolitic Ngozi volcano contains a 3-km-wide caldera with a 1.5 × 2.75 km lake in the southern part of the caldera. Ngozi lake is the second largest crater lake in Africa. The caldera is bounded by steep-walled cliffs 150–300 m high and could be of Holocene age due to its irregular shape (c.f. Fontijn et al. 2012). Only two of Ngozi’s deposits...
KeywordsHolocene Debris Flow Tephra Late Miocene Pyroclastic Density Current
- Harkin DA (1960) The Rungwe Volcanics at the Northern End of Lake Nyasa. Geol Surv Tanganyika Mem 2:1–172Google Scholar
- Ivanov AV, Rasskazov SV, Boven A, Punzalan L, Brandt IS, Brandt SB, Fernandez-Alonso M (1999) Timing and Late Cenozoic volcanic activity and rift basin formations in the Rungwe province of Tanzania substantiated by K–Ar and 40Ar/39Ar dating. In: Proceedings of Rifting in Intracontinental Setting: Baikal Rift System and other Continental Rifts, 22–30 August 1999, Irkutsk and Lake Baikal, Russia, pp 75–79Google Scholar
- Lenhardt N, Oppenheimer C (2014) Volcanism in Africa: geological perspectives, hazard assessment and societal implications. In: Ismail-Zadeh A, Urrutia-Fucugauchi J, Kijko A, Takeuchi K, Zaliapin I (eds) Extreme natural hazards, disaster risks and societal implications, IUGG Special Publication Series. Cambridge University Press, Cambridge, pp 169–199CrossRefGoogle Scholar
- Morrissey M, Zimanowski B, Wohletz K, Buettner R (2000) Phreatomagmatic fragmentation. In: Sigurdsson H, Houghton B, McNutt SR, Rymer H, Stix J (eds) Encyclopedia of Volcanoes. Academic Press, London, pp 431–445Google Scholar
- Schmincke H-U, van den Bogaard P, Freundt A (1990) Quaternary Eifel Volcanism. Excursion guide, workshop in explosive volcanism. IAVCEI International Volcanology Congress Mainz (FGR), Pluto Press, Witten, pp 1–188Google Scholar
- Siebert L, Simkin T, Kimberly P (2010) Volcanoes of the World, 3rd edn. University of California Press, BerkeleyGoogle Scholar
- Wohletz KH (1998) Pyroclastic surges and compressible two-phase flow. In: Freundt A, Rosi M (eds) From magma to tephra. Elsevier, Amsterdam, pp 25–51Google Scholar
- Wohletz KH, Sheridan MF (1979) Model of pyroclastic surge. Geol Soc Am Pap 180:177–194Google Scholar