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2005
- handle: 10670/1.wzsttl
- halshs: halshs-00004023
info:eu-repo/semantics/OpenAccess
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Ethiopia Awash basin Melka Kunture Balchit ICP-MSSujets proches
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Jean-Paul Raynal et al., « Balchit Obsidian (Upper Awash, Ethiopia) », HAL-SHS : archéologie, ID : 10670/1.wzsttl
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The small volcanic massif of Balchit is one of the Pliocene silicic centers of the Wechecha Formation (Addis Ababa Rift Embayment). It is located some 25 km SE of Addis Ababa and 7 km NE of Melka Kunture, on the left interfluve of the Awash river. and has recently been dated at 4.37±0.07 Ma by K-Ar. It constitutes a major obsidian source-area. In the vicinity of Melka Kunture, obsidian is a major component of lithic series since the Oldowayan. Since 1999, new investigations have been undertaken on the prehistory and volcano-sedimentary environments of Melka Kunture and a special attention was paid to obsidian artefacts and its primary and secondary sources. Analyses were performed on several obsidian samples from various locations, both in situ from a lava flow of Balchit and reworked debris or pebbles from different alluvial formations of the Awash river and its tributaries. The trace element contents of two Balchit samples from the main obsidianbearing lava flow and of nine obsidian pebbles from alluvial deposits were determined by ICP-MS at LGCA (Grenoble) and at SOCFAC (Southampton), using the same experimental procedure. Six obsidians pebbles were found to present the same (type A) elemental composition as the two Balchit obsidians and therefore might come from this mother-rock. The three other obsidians present specific trace element systematics dubbed respectively as types B, C and D.