Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12136/317
|Title:||The geology and chronology of the acheulean deposits in the Mieso area (East-Central Ethiopia)|
Barfod, Dan N.
McHenry, Lindsay J.
Torre, Ignacio de la
|Keywords:||Alluvial sequence;40Ar/39Ar dating;Tephrochemistry;Pleistocene;SE Afar margin|
|Citation:||Journal of Human Evolution, 2014, 76, 26-38|
|Abstract:||This paper presents the Quaternary sequence of the Mieso area of Central-East Ethiopia, located in the piedmont between the SE Ethiopian Escarpment and the Main Ethiopian Rift-Afar Rift transition sector. In this region, a piedmont alluvial plain is terraced at +25 m above the two main fluvial courses, the Mieso and Yabdo Rivers. The piedmont sedimentary sequence is divided into three stratigraphic units separated by unconformities. Mieso Units I and II contain late Acheulean assemblages and a weakly consolidated alluvial sequence, consisting mainly of fine sediments with buried soils and, to a lesser degree, conglomerates. Palaeo-wetland areas were common in the alluvial plain, represented by patches of tufas, stromatolites and clays. At present, the piedmont alluvial surface is preserved mainly on a dark brown soil formed at the top of Unit II. Unit III corresponds to a fluvial deposit overlying Unit II, and is defined by sands, silty clays and gravels, including several Later Stone Age (LSA) occurrences. Three fine-grained tephra levels are interbedded in Unit I (tuffs TBI and TA) and II (tuff CB), and are usually spatially-constrained and reworked. Argon/argon (40Ar/39Ar) dating from tuff TA, an ash deposit preserved in a palustrine environment, yielded an age of 0.212 ± 0.016 Ma (millions of years ago). This date places the top of Unit I in the late Middle Pleistocene, with Acheulean sites below and above tuff TA. Regional correlations tentatively place the base of Unit I around the Early-Middle Pleistocene boundary, Unit II in the late Middle Pleistocene and within the Late Pleistocene, and the LSA occurrences of Unit III in the Late Pleistocene–Holocene.|
|Appears in Collections:||Geocronología y Geología|
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