Tahalra volcanic field

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.

Tahalra volcanic field
Tahalra volcanic field
Highest point
Elevation	1,467 m (4,813 ft)[1]
Coordinates	22.67°N 5°E / 22.67; 5[1]

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]

See also

• List of volcanic fields