Stratigraphic framework of pulsed volcanism in central Ethiopian plateau

Abstract This paper presents new stratigraphic correlation and naming for younger basalt lavas (<24 Ma) and enclosed rhyolites near the intersection of the southern Red Sea rift and the Ethiopian rift valley, based upon three volcano-stratigraphic sections located over about 30 kilometres, and they bracket the timing of eruption of the upper sequence with existing geochronology. The correlations are based on the petrography (thin sections) of ca. 32 samples taken from these three sections, combined with outcrop description. The stratigraphy is proposed as 5 new formations, partially placed into an existing stratigraphic framework, based on the dominant unit-basalt or rhyolite in the package of sequences. These new stratigraphic columns also include non-volcanic units (interlayered sedimentary strata, paleosols and weathering surfaces), which are not usually described in the volcanic pile, showing that there was more complexity in this succession than previously known. This new stratigraphic framework will encourage more geochronology and geochemistry studies that are sorely needed.