Tahalra volcanic field
Tahalra volcanic field is located in Algeria
Tahalra volcanic field
Tahalra volcanic field
Highest point
Elevation1,467 m (4,813 ft)[1]
Coordinates22°40′N 5°00′E / 22.67°N 5°E / 22.67; 5[1]

Tahalra volcanic field is a volcanic field in Algeria. It consists of a Miocene lava plateau and a number of Pliocene to Holocene age individual vents, including cinder cones.

Geography and geomorphology

Tamanrasset lies east-northeast from the field. Cinder cones, lava domes, lava flows and maars form the field, which covers a surface of 1,800 square kilometres (690 sq mi)[1] elongated west to east.[2] There are about 132 individual vents[1] in the area measuring 30 by 80 kilometres (19 mi × 50 mi).[3]

Geology

Tahalra is part of a province of volcanic fields in the Hoggar, which has been active since the Mesozoic.[3] Seismic tomography has shown the existence of low-velocity mantle beneath the Tahalra and Atakor volcanic fields, sign of the presence of recent volcanism.[4]

The basement beneath the field consists of rocks of Precambrian age, mostly metamorphic rocks and plutons[1] which are part of a mobile belt at the margin of the West African Craton. Parts of the basement are covered with Paleozoic rocks.[3]

The field has erupted basalt, basanite, rhyolite and trachyte.[1] They contain amphibole, clinopyroxene, magnetite and olivine phenocrysts.[3] Patterns in trace element composition and isotope ratios imply that the magmas either developed from variable starting material or from metasomatized mantle.[5]

Eruptive history

Volcanic activity started in the Miocene and led to the development of a lava plateau up to 100 metres (330 ft) thick.[3] Eruptions continued in the Pliocene and the Pleistocene,[1] forming many individual vents.[3] Maars and cones in the northern part of the field are of Pleistocene and Holocene age (Paleolithic to Neolithic[3]).[1]

References

  1. 1 2 3 4 5 6 7 8 "Tahalra Volcanic Field". Global Volcanism Program. Smithsonian Institution.
  2. ↑ Dautria et al. 1988, p. 19.
  3. 1 2 3 4 5 6 7 Dautria et al. 1988, p. 18.
  4. ↑ Ayadi, A; Dorbath, C; Lesquer, A; Bezzeghoud, M (February 2000). "Crustal and upper mantle velocity structure of the Hoggar swell (Central Sahara, Algeria)". Physics of the Earth and Planetary Interiors. 118 (1–2): 120. Bibcode:2000PEPI..118..111A. doi:10.1016/S0031-9201(99)00134-X. ISSN 0031-9201.
  5. ↑ Dautria et al. 1988, p. 33.

Sources

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.