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In the central sector of the Main Ethiopian Rift, the Ziway–Shala lake basin system includes four present-day residual lakes, from north to south, lakes Ziway, Langano, Abijata, and Shala. This region of East Africa is under the influence of the Intertropical Convergence Zone seasonal migration. Thus it has been designated as a potential core site by the ERICA Project (`Environmental Research for Intertropical Climate in Africa'). The four lakes have been subjected to strong changes in water level and water salinity at least during the Late Pleistocene. The purpose of this study is to produce a model of basin formation and sediment accumulation for this system of lakes, in order to separate the effects of climatic change from environmental variations induced by local or regional factors such as volcano-tectonic forcings. In addition to an exhaustive synthesis of available data, various investigations have been used to develop this model: 3D remote sensing, high-resolution seismics, coring, and structural, sedimentological, and hydrological field studies. New AMS radiocarbon dating helped to refine the pre-existing stratigraphic framework for this region, and basin age estimations were calculated using mean sediment accumulation rates. The history of the Ziway–Shala lake basin system has been reconstructed from the Late Pliocene–Early Pleistocene period (106 yr), mainly characterized by catastrophic explosive volcanic eruptions. The early-middle Pleistocene–Late Pleistocene period (104–106 yr) was marked by a regional volcano-tectonic paroxysm, resulting in major changes in the morphology of the area, with the formation of the Abijata, Ziway and Shala lake basins. From ∼0.20 Ma, the Ziway–Shala basin history is marked by the eastward migration of volcano-tectonic activity, resulting in the development of the youngest basin of the Ziway–Shala system, the Langano Basin. The joint history of sedimentation in the Ziway, Langano, Abijata, and Shala lake basins started during the early-Late Pleistocene period (101–104 yr) and is characterized from this period up to the present-day by a series of climatically controlled rises and falls of lake level.

The Mesozoic-Tertiary Aquitaine basin overlaps the Aquitaine block and the northern edge of the Iberian margin. Both units are situated in the southwesternmost part of the European Continent. The Aquitaine shelf is a stable platform overlying a relatively thin crustal segment; it underwent extensional block faulting and many of its folded structures are related to salt tectonism. The Iberian block is a thicker lithospheric unit that acted as a buttress. At the junction of these two structural domains the South Aquitaine or North Pyrenean area developed, where crustal stretching, rifting, wrenching, and orogenic compression were maximal from the Mesozoic to the Tertiary. The history of the basin has been a suite of rifting attempts, in the context of the progressive opening of the Bay of Biscay, which never completely succeeded. The relative plate motions and the later convergence led, nevertheless, to the formation of the Aquitaine basin and to the emergence of the Pyrenean fold belt. The Mesozoic-Tertiary sedimentary infill of the basin is mostly marine, with thick evaporites, stable platform carbonates, subsiding platform shaly-calcareous deposits, and a characteristic, diachronous turbiditic (flysch) and molasse complex. Events during the basin-forming, extensional, and translational periods contributed more to the generation of the hydrocarbon accumulations than did the effects of the subsequent compressive structural regime. The latter, however, may have enhanced thermal flow and, thus, maturation of hydrocarbon source rocks.

a UMR CNRS 6538 ‘‘Domaines Oceaniques’’, Institut Universaire Europeen de la Mer, Universite de Bretagne Occidentale, place Nicolas Copernic, 29280 Plouzane, France b EP 1748 CNRS, Equipe Hydrologie, Paleohydrologie et Paleoenvironnement, Universite Paris-Sud, Bâtiment 504, 91405 Orsay Cedex, France c Laboratoire d’Hydrogeologie, Universite d’Avignon et des Pays du Vaucluse, 33 rue Louis Pasteur, 8400 Avignon Cedex, France d 3 Rue des Ajoncs, 64160 Morlaas, France e CEREGE, B.P. 80, 13545 Aix-en-Provence Cedex 04, France f Laboratoire ‘‘Environnements sedimentaires et Stratigraphie’’, Universite de Perpignan, 52 avenue de Villeneuve, 66860 Perpignan, France g Department of Geology and Geophysics, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia h Royal Belgian Institute of Natural Sciences, Freshwater Biology, Vautierstraat 29, B-1000 Brussels, Belgium i Department of Earth Sciences, Via Universita 4, 41100 Modena, Italy