Tahalra Volcanic Field

The large E-W elongated Tahalra volcanic field covers an area of about 1,800 km2 in the Hoggar Province of southern Algeria. It lies WSW of the town of Tamanrasset and was active from the Miocene to the Holocene, producing alkaline Strombolian cones and lava flows. The field was constructed over Precambrian metamorphic and plutonic rocks of the Tuareg shield. A dozen trachytic-to-rhyolitic lava domes and spines formed during the Pliocene, and Pliocene-to Pleistocene activity formed about 100 small basaltic (mostly basanitic) cones. The most recent activity, during the Pleistocene and Holocene, produced about 20 maars and cones along the northern margin.