Touchard, Yannick; Rochette, Pierre; Aubry, Marie-Pierre; Bassinot, Franck (1999): Global tephra layers from the Ethiopian Traps; a clue to evaluate trap climatic impact. IUGG, [location varies], International, In: Anonymous, IUGG 99; abstracts, 99, Week A, 113, georefid:2003-008286

A precise stratigraphic study of the Ethopian traps has demonstrated that the emplacement of the main flood sequence has occurred at 30 + or -0.5 Ma (Ar/Ar dating) and within magnetochron 11, with a maximum duration of either 0.8 or 1.9 Myr, depending on when magnetostratigraphic solution is chosen. Four acidic tephra layers have been found in leg 115 sediments, 2600 km to the SE, with magnetostratigraphic ages synchronous with acidic layers of the traps section (in the 0.8 Ma solution). This supports the "short" hypothesis, leading to magma production rate >1.6km3/yr. The Ethiopian origin of the tephra material (glass shards) has been confirmed by distribution of major and trace elements together with isotopic studies. For the first time, trap products are found within distant marine sequences, allowing one to discuss with much more confidence the climatic impact of trap atmospheric emissions. Perfectly synchronous susceptibility peaks--interpreted as the results of volcanic input--are found in the South Atlantic 522 site. Together with the characteristics of intertropical global atmospheric circulation, this strongly suggests that the glass shards have been disseminated globally, at least in the intertropical band, during explosive eruptions largely exceeding the Toba tuff eruption. A sudden global cooling should therefore be associated with each tephra layer. However the well established global cooling event Oi2 appears below the tephra layers, that is during the early flood basalts emplacement. Micropaleontological evidences and deltaO18 stratigraphy will be used to discuss these correlations.
West: -5.0647 East: -5.0646 North: -26.0650 South: -26.0651
Expedition: 73
Site: 73-522
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