Facies associations of the northern Dandiero Basin (Danakil depression, Eritrea, including the Pleistocene Buya homo site)

摘要

The Dandiero Basin is located on the northern part of the 300?km-long Danakil depression. The geologic succession filling the Dandiero Basin is up to 1000?m thick and consists of three synthems, inascending order: the Early-to-Middle Pleistocene Maebele Synthem of fluvio-lacustrine origin; the Late Pleistocene Curbelu Synthem of alluvial deposits and the Late Pleistocene to Holocene Samoti Synthem alluvio-eolian sand. This study and map (1:5000 scale) focuses on the Maebele Synthem exposed in a 3.8?km~(2) area near Mt. Alat. Regionally, the Maebele Synthem consists of six lithostratigraphic units, in ascending order: (1) the Bukra Sand and Gravel, (2) the Alat Formation, (3) the Wara Sand and Gravel, (4) the Goreya Formation, and (5) Aro Sand, (6) Addai Fanglomerate. The Bukra Sand and Gravel is about 150–200?m thick and made up mainly of fluvial sand. The Alat Formation is 70–100?m thick and consists of alternating fluvial, lacustrine and deltaic deposits. Fluvial deposits consist of sand-filled channels that occur as amalgamated or isolated bodies within floodplain mud. Lacustrine sediments consist of mud, whereas deltaic deposits are represented by sandy shallow-water and Gilbert-type deltas. The Wara Sand and Gravel (250?m thick) is made up of fluvial sand. The Goreya Formation (50?m thick) consists of lacustrine, deltaic and fluvial deposits. The fluvial deposits consist of sand-filled channels the lacustrine sediments consist of mud with subordinate limestone, and the deltaic deposits are represented by sandy shallow-water deltas. The Aro Sand consists of fluvial sand up to 120?m thick. The Addai Fanglomerate (250–300?m thick) consists of coarse-grained alluvial fan.