Structural Meaning of East-Central Afar Volcanism (Ethiopia, T.F.A.I.)

• Published in: The Journal of geology 1975-01, Vol.83 (3), p.363-373
• Main Authors: Civetta, L., de Fino, M., Gasparini, P., Ghiara, M. R., La Volpe, L., Lirer, L.
• Format: Article
• Language: English
• Subjects: Basalt; Geochemistry; Geology; Igneous petrology; Olivine; Plagioclase; Plumes; Tectonics; Volcanism; Volcanoes
• ISSN: 0022-1376; 1537-5269
• DOI: 10.1086/628098

The volcanic units outcropping in southeastern central Afar include a sequence of thick, stratoid lava flows with interbedded acidic rocks, ranging in age from 25 to 1 m.y. This sequence is overlain by a number of volcanic ranges, some of them in axial position (Manda-Inakir) and others trans-versally oriented in respect to the axis of the depression (Assab, Edd). The age of all these volcanic ranges seem to be younger than 0.6 m.y. The flood basalts sequence is not well defined from a petrological and geochemical standpoint: its products range from mildly alkaline to alkali-basaltic terms. On the contrary, each volcanic range is well characterized in terms of the nature of its products; Manda-Inakir products form a series starting from mildly alkaline basalts and the transversal volcanic ranges consist of typical alkaline series. The geochemical characters of these rocks seem to be roughly consistent with the general evolution pattern inferrable for a spreading area.