Abstract The central Kenya Rift extends from about 1"N to0010'N and is bounded by the Elgeyo fault scarp in the west and the Laikipia fault scarp 70 km to the east (Figure1). Within this semi-arid region, there are a series of geographically and temporally distinct fault-bounded basins with fluvial and lacustrine sediments that have developed and been destroyed because of combined tectonic, volcanic, and climatic controls. These Neogene basins have tended to shift eastward with time as rift extension has progressed (Chapman and Brooke,1978; Chapman et al., 1978). Their sediments include the Miocene Kimwarer and Tambach Formations along the Eigeyo border-fault (Murray-Hughes, 1933; Shackleton,1951; Lippard, 1972; Ego, 1994; Renaut et al.,1999), several Miocene-Pliocene successions exposedin the Tugen Hills (King and Chapman, 1972; Chapmanet al., 1978; Hill et al., 1985; Hill, 1995), and the Pleistocene Kapthurin Formation and modern Lake Baringo in the eastern axial part of the rift (Figure 1)(Tallon, 1978; Renaut et al., this volume). The Tugen Hills, also known as Kamasia, is a largenorth-south trending tilt block that dips westward and rises to more than 1000 m above the rift floor. Pleistocenefaulting and erosion have exposed a sequence of more than 3000 m (Hill et al., 1986) of interbeddedfluvial and lacustrine sedimentary rocks and lavas,principally phonolites, trachytes, and basalts (Figures1, 2). Lacustrine sedimentary rocks, includingdiatomaceous shales, silts, and weakly lithified siltstones, are found in the Miocene Ngorora and Lukeinoformations and the Pliocene-Pleistocene Chemeron Formation (Figure 1). To date, few detailed mineralogical and paleolimnological studies of these sediment shave been undertaken.

Abstract A revised amphibian zonation for the European Pennsylvanian and Cisuralian (Upper Carboniferous to Lower Permian) with nine amphibian zones is presented. The index fossils belong to species-chronoclines with two or three closely related species. The time resolution of these amphibian zones is about 1.5–3.0 Ma. Biostratigraphical correlations with amphibian zones are applicable to 16 basins in the Czech Republic, Poland, France, Italy and Germany. The biostratigraphical potential of other tetrapods is discussed.

Abstract The northern (NKR) and central (CKR) segments of the Kenya Rift are among the most important areas of the East African rift system for hydrocarbon prospecting because they offer the oldest and longest lived sedimentary basins and they are a crossover area between Ce-nozoic and Cretaceous rifts. During the 1970s and 1980s, the interest of oil companies focused in the Turkana depression and the northeastern region of Kenya. Seismic reflection surveys and several exploration wells enabled the identification of several deeply buried basins: (1) In the NKR, three strings of north–south-oriented half grabens, the oldest known basins being of Cretaceous?–Paleogene to middle Miocene age; (2) In the CKR, two north–south half grabens, the Baringo-Bogoria Basin (Paleogene–Present), and the Kerio Basin (Paleogene–upper Miocene). All basins are filled by up to 8 km (5 mi) thick sediments of alluvial, fluviodeltaic, or lacustrine origin and volcanics of late Eocene to Neogene age. New studies have focused on reservoir and/or source rock quality in several of these basins. In terms of hydrocarbon potential, arkosic sand stones in CKR or NKR demonstrate a fair to good reservoir quality, with porosity up to 25%. Strong changes in terms of diagenetic alteration relate to deformation events or change in sediment source as a result of tectonic activity and hydrothermal fluid circulation associated with volcanism. High-quality source rocks were deposited in freshwater lake environments under a tropical climate. Such environments have been identified during the Paleogene in the NKR and lower Neogene in the CKR. The combination of reservoir and source rock characteristics results in a provisional classification of each studied basin, in terms of very high to medium potential for hydrocarbons.

Abstract During Late Carboniferous-Early Permian times dextral transtensional movements along the NW-trending Franconian Fault System and parallel faults caused complex block faulting in the Thuringian Forest region, Germany, accompanied by intense magmatism. This is well constrained by geochronological data ( 207 Pb/ 206 Pb single zircon, SHRIMP, 40 Ar/ 39 Armica, zircon fission-track ages), field relations, and the sedimentary record from the Ruhla Crystalline Complex (RCC) and surroundings. The combined dataset indicates that the Ruhla Crystalline Complex was faulted into three nearly N–S-trending segments, which underwent different exhumation histories during Late Carboniferous–Permian times. The central segment of the RCC was exhumed by several kilometres as a horst block, while the eastern and western segments subsided simultaneously, forming the basement to the Oberhof and Eisenach molasse basins, respectively. Late Carboniferous–Permian uplift of the central segment is constrained by 40 Ar/ 39 Ar cooling ages of 311 ± 3 (muscovite) and 294−288 ± 3 Ma (biotite), a weighted zircon fission-track age of 272 ± 7 Ma and overlying Zechstein sediments. In contrast, the eastern segment shows much older 40 Ar/ 39 Albiotite cooling ages between 336 ± 4 and 323 ± 3 Ma, was exposed at c. 300 Ma, and subsequently covered by molasse sediments and volcanic rocks between 300 and c. 275 Ma. A similar Late Carboniferous evolution is inferred for the western segment, as it is also overlain by Lower Permian volcanic rocks and has a 297 ± 29 Ma single zircon fission-track age. Simultaneous horst and basin formation is additionally constrained by granite pebbles in conglomerates of the Oberhof and Eisenach basins. These pebbles can partly be derived from granites in the central segment of the RCC. Age data and the orientation of granitoid bodies and dykes in the Ruhla Crystalline Complex and its surroundings provide evidence for the opening of NE-trending structures between 300 and 294 Ma, and formation or reactivation of W- to NW-trending structures between 290 and 275 Ma. Magmatic activity in the Thuringian Forest region may have been caused by widespread mantle upwelling in central Europe during the Late Carboniferous-Early Permian.

Abstract In order to take into account the studies of the European and American (USA) collections carried out by one of the authors, and of the recent nomenclatural revisions from new footprint discoveries, which have occurred during the last decade, the authors present a critical review of the French Permian palichnofauna. The distribution of the ichnospecies in the stratigraphy of the Lodève Basin, taken as a reference, is outlined. The ichno-associations are then compared with those of other French (Provence), European (Italy, Germany) and USA basins. Based on the ages of different ichnofossiliferous formations, three successive ichnofaunal units can be distinguished in the Permian of Europe. The first developed in the Cisuralian (Asselian to Kungurian). The second is found in the south of France in Kazanian to Lower Tatarian strata, equivalent to the Roadian-Wordian. The third and youngest, dated as Lopingian, is only found in Italy, in the Bolzano Basin. Because of sedimentary gaps, limited observations, sometimes erroneous determinations, and ichnospecies with great vertical distribution, it currently appears that footprints have a low utility for biochronological resolution. Nevertheless, they allow us to discriminate three time intervals in the Permian, as is also the case for skeletal remains.