Tahalra volcanic field
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| Tahalra volcanic field | |
|---|---|
  Tahalra volcanic field | |
| Highest point | |
| Elevation | 1,467 m (4,813 ft)[1] |
| Coordinates | 22°40′N 5°00′E / 22.67°N 5°E[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.
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]