Manzaz volcanic field

Manzaz volcanic field is a volcanic field in Algeria. It consists of scoria cones with lava flows and has been active until recently.

Manzaz volcanic field
Manzaz seen from space
Highest point
Elevation1,672 m (5,486 ft) [1]
Coordinates23.92°N 5.83°E / 23.92; 5.83 [1]
Geography
Manzaz volcanic field

Geography and geomorphology

The field lies in Hoggar, close to the Atakor volcanic field.[1] A dome-like uplift has been associated with the volcanism in the region.[2] The presence of volcanism has been explained by tectonic events associated with the collision between Europe and Africa, and the resulting reactivation of ancient tectonic lineaments.[3]

The field consists of scoria cones and covers a surface of 1,500 square kilometres (580 sq mi). Many of these have breaches[1] and are heavily eroded. The cones were strombolianically active[4] and have erupted lava flows.[1] Volcanic ash and pyroclastics are also found.[5] Oukcem is a maar in the field[1] that consists of two separate craters with diametres of 500 metres (1,600 ft) and 700 metres (2,300 ft) respectively. They are surrounded by tuffs and natron is found at the bottom of the larger crater.[6]

Geology

The basement consists of metamorphic and plutonic rocks of Precambrian age, which are part of the Tuareg shield.[1] Outcrops of granite are found in some places.[7] These were first buried by tholeiitic basalts between 35 and 30 million years ago.[2]

The field has mostly erupted basalt and basanite. Xenoliths include peridotite and pyroxenite,[1] and amphibole and feldspar form megacrysts in the rocks.[4] Xenoliths appear to, in part, originate from a metasomatized mantle.[8] The total volume of erupted rocks is about 175 cubic kilometres (42 cu mi).[9]

Eruptive history

Three phases of volcanic activity have been distinguished at Manzaz, the first between 20 and 12 million years ago, the second between 7 and 4 million years ago and the third between 3 and 0.01 million years ago.[9] Volcanic activity continued into the Holocene. Some young volcanoes developed on terraces of Neolithic age.[1]

References
  1. "Manzaz Volcanic Field". Global Volcanism Program. Smithsonian Institution.
  2. Beccaluva et al. 2007, p. 483.
  3. Beccaluva et al. 2007, p. 492.
  4. Foulger 2005, p. 388.
  5. Foulger 2005, p. 387-388.
  6. Benhallou, Amel (2004-06-02). "Twin maars of Oukssem (Manzaz, Northern Tamanrasset, Hoggar): a volcanic curiosity". Cite journal requires |journal= (help)
  7. Foulger 2005, p. 387.
  8. Beccaluva et al. 2007, p. 490.
  9. Foulger 2005, p. 383.

Sources
  • Beccaluva, L.; Azzouni-Sekkal, A.; Benhallou, A.; Bianchini, G.; Ellam, R.M.; Marzola, M.; Siena, F.; Stuart, F.M. (August 2007). "Intracratonic asthenosphere upwelling and lithosphere rejuvenation beneath the Hoggar swell (Algeria): Evidence from HIMU metasomatised lherzolite mantle xenoliths". Earth and Planetary Science Letters. 260 (3–4): 482–494. doi:10.1016/j.epsl.2007.05.047. ISSN 0012-821X.CS1 maint: ref=harv (link)
  • Foulger, Gillian R. (2005-01-01). Plates, Plumes, and Paradigms. Geological Society of America. ISBN 9780813723884.CS1 maint: ref=harv (link)
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