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The Baringo Trachyte Fault System is located within the central Kenya Rift and forms part of a N–S-trending linked extensional fault network. This fault system bounds to the west the 8 km deep Baringo Basin which itself lies within the axial valley of the central Kenya Rift. It mainly affects a middle Pleistocene trachytic dome (510 ka), the so-called Baringo Trachyte (BT). A morphotectonic study of the 10 km long BT master fault and associated downthrow geometries provides constraints on the evolution of a magma-type rift fault system from an initial stage of crack opening through to propagation. A model of radial fault growth is proposed in order to account for the longitudinal segmentation of the main fault escarpment from the median part to the tips. The small-scale half-graben geometry developed in the median high-strain zone is progressively accommodated laterally by both flexure and related narrow compensation grabens. The resulting crack swarms are well-developed at the free southern tip zone. Both the spatial distribution of rock-breaking products and their relations to the immediate hangingwall provide further evidence for this hypothesis. Well-developed screes and other gravity-driven structures (slumps) preferentially occur along the median part of the Baringo Trachyte Fault Escarpment, probably as earthquake-induced features. The hangingwall fault zone shows an asymmetrical triangular-shape with a maximum width of about half the length of the main scarp. This zone of maximum deformation and subsidence appears to be laterally controlled by two major, conjugate, transverse basement discontinuities lying with a conjugate geometry. Its internal architecture is dominated by antithetic westerly-dipping normal faults bounding discrete half-grabens, locally infilled by syn-tectonic volcaniclastics. Chronological data on hydrothermal silica filling open cracks on the BT footwall suggest that the master fault evolution occurred from 345 to 198 ka, as the possible result of at least four major normal faulting earthquakes.

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