Compositional Variation of Erta’ale Basaltic Eruption with Time

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa Universty


Erta’Ale lava lake is located at the center of the Erta’Ale volcanic range in the northern afar depression. Erta’Ale is known by its two active lava lake situated at northern and central part of the caldera. The thesis generally considered the compositional variation of the Erta’Ale lava through time. Field investigation, petrographic and whole rock geochemical studies have been applied to meet the objectives. The lava of Erta’Ale volcano has MgO content ranging from (4.56-6.36 wt%) and SiO2 content (47-52 wt%) which decrease with increasing of MgO. The Al2O3 and CaO contents slightly increase with decreasing MgO down to ~6 wt%, and then decrease with decreasing of MgO a general positive trend for Fe2O3 and TiO2. The variations diagram of the Erta’Ale lava show fractionation of mineral phase. In most of the Erta’Ale lava (Ce/Pb > 20) crustal contamination is not major process. However there are some samples which have low value of Ce/Pb ratio (<20) because of their high value of Pb . The Erta’Ale lava is characterized by low La/Nb (<1) and Ba/Nb (<5) which is the characteristics of mantle plume derived melts. Trace element data of the Erta’Ale basalt show that the source of the Erta‘Ale basalt is Afar Mantle plume. The La/Nb, La/Sm and Ce/Pb versus time diagram indicate that the source, depth and degree of melting of the Erta’Ale basalt don’t have a significant change with time. The geochemical results show that there is no significant compositional variation in the Erta’Ale basaltic rock. However, there is a slight chemical variation between the 2017, 2010 and the others older lava. This variation is a result of the difference in degree of fractionation.