[2] Gharyan is one among several intraplate volcanic fields in Africa, which include Haruj, Hoggar, Jebel Marra and Tibesti.

They are linked either with crustal domes or rifts and appear to be the consequence of lithosphere-mantle processes such as mantle plumes.

[5] The location of these vents appears to be controlled by a neighbouring graben and tectonic fractures.

[2] The field has erupted basanite and phonolite with a total volume of about 350 cubic kilometres (84 cu mi),[1] additional volcanic rocks are basaltic andesite, hawaiite and tephrite.

[6] Potassium-argon dating has yielded an age of about 12 to 1 million years ago for the field;[1] activity commenced in the Eocene with the basaltic plateau and continued in the late Eocene and later with lava domes and individual volcanoes.