A comment on “Geomorphic development of the escarpment of the Eritrean margin, southern Red Sea from combined apatite fission-track and (U–Th)/He thermochronometry” by Balestrieri, M.L. et al. [Earth Planet. Sci. Lett. 231 (2005) 97–110

Abstract

Published without an abstract. From the introduction: The western Red Sea margin in Eritrea comprises 25 km of coastal lowlands backed by a deeply eroded escarpment that rises > 2.2 km in 40 km. The plateau atop this zone of Neogene uplift is capped by 30 Ma continental flood basalts (CFB). The CFBs rest conformably on thin Palaeogene (> 40 Ma) lateritic palaeosols [1], beneath which is a Neoproterozoic metamorphic complex. In the southern part, the laterites are separated from basement by discontinuous patches of Jurassic sandstones. The laterites observed in the field and on satellite images occur in this stratigraphic position throughout the hinterland of the western Red Sea margin from eastern Sudan [2] through Eritrea and northern Ethiopia [3] and [4] to the Blue Nile Gorge [5] (a N–S range of > 800 km), and further to the south [6]. Because they formed on a low-relief surface close to sea-level [7] across most of NE Africa and western Arabia [4], the laterites are an important datum for assessing the later effects of regional tectonics [3] and [8]. Post-30 Ma tectonics has displaced occurrences of this datum on the plateau and coastal lowlands by 2.2–2.8 km vertically. The opportunities presented by the laterite datum clearly encouraged Balestrieri et al. [9] and Abbate et al. [10] to analyse geomorphic processes at the western Red Sea margin thermochronologically. So too did previous work on the initiation of rifting in the Red Sea and Gulf of Aden areas [7], [11], [12] and [13], which converged on initiation of uplift and erosion from 25 to 20 Ma. On the basis of 13 apatite (U–Th)/He cooling ages (apatite He ages) from the Eritrean escarpment, Balestrieri et al. [9] conclude a 10 Ma younger age for the start of rifting in the southern Red Sea.