Oyma
Oyma is a rhyolitic volcano, probably of peralkaline composition, with a partial summit caldera.
Complete list of alkaline rocks and carbonatites
Oyma is a rhyolitic volcano, probably of peralkaline composition, with a partial summit caldera.
A rhyolitic volcano, probably of peralkaline composition, lying immediately south of Oyma (No. 10). There are spatter cones and associated basaltic flows.
This is a small rhyolitic volcanic centre which is probably of peralkaline composition.
Gabal is a volcano which includes peralkaline rhyolites. An analysis of a pantellerite is given in Barberi et al. (1975a).
Ela comprises flows, domes, ignimbrites and tuffs of rhyolitic, and probably peralkaline, composition.
Lying just to the southwest of 'Ela (No. 14), Gad 'Elu is probably of similar composition but is a much bigger centre. Obsidian flows are particularly abundant. Analyses of comenditic rhyolites, in which generally K2O>Na2O, are in Barberi et al. (1975a).
Dawa Ale is a rhyolitic volcano, probably of peralkaline composition, of flows, domes, ignimbrites and tuffs. There is a well developed caldera and peralkaline microgranite feeder dykes for the volcanics have been observed.
The Affara Dara peralkaline granite is exposed over 35x25 km but to the west is partially covered by younger basalts that emanated from the Alayta and Boina eruptive centres.
This is a rhyolitic volcanic centre which is of peralkaline composition. There are spatter cones and associated basaltic flows. Analyses of two pantelleritic obsidians are given by Barberi et al. (1975a).
The name Dabbahu is a general one for this volcanic region the upper part of which is called Boina. Barberi et al. (1975b), however, proposed that the term Boina be applied to the whole volcanic unit.