Abstract The Hebron Fault in SW Namibia is associated with a <1 m to 9.6 m high scarp displacing Proterozoic basement and Middle to Late Pliocene crystalline conglomerates. The young age of strata exposed in the fault scarp together with evidence for displacement of aeolian dunes, post-dating the Middle Stone Age, suggests that latest fault displacements occurred during the Late Pleistocene to recent. Recorded historical seismic events show that the fault zone is still active. Latest movements of the fault are recorded by: down-to-the-SW offset of calcrete-cemented conglomerate; fluvially modified, asymmetric hanging wall, graben-like structures; at least two left-stepping jogs in the fault trace and structural data from basement rocks in which late-stage crush zones overprint earlier cataclasite. These features provide consistent evidence that the present scarp formed predominantly by normal dip-slip displacement on a NW-striking, steeply SW-dipping master fault with only a minor dextral strike-slip component. Strongly veined cataclastic fault rocks adjacent to the scarp in basement most probably originated at depths of 4–10 km. The conclusion is therefore that recent fault activity has reactivated a pre-existing, much older fault. Aerial photographic lineaments and similar fault scarps identified NW and SE of the present study area are interpreted as extensions of the same fault structure. Hence the total length of the Hebron Fault is at least 300 km subparallel to the Atlantic margin of southern Africa. Our observations confirm that the Hebron Fault is a neotectonic feature of regional significance that may relate to late Cenozoic and particularly Quaternary neotectonic activity in NE Namibia and NW Botswana.

Abstract The Permian (299-251 Ma; Wardlaw et al. 2004 ) succession of Central Europe records the change from a Pangaea configuration and compressive tectonic regime inherited from the Variscan Orogeny, to the development of the broad thermal subsidence-controlled Southern Permian Basin and its inundation by the Zechstein Sea. During latest Carboniferous-Early Permian times, the final phase of Variscan orogenic extension produced a series of small strike-slip and extensional continental basins across central and western Europe. Within these basins Stephanian and Lower Rotliegend continental successions were deposited. Subsequent thermal subsidence led to the gradual coalescence of these isolated basins to form the large Southern Permian Basin which extended across much of central and western Europe (Fig. 10.1 ). Early Permian sedimentation was predominantly fluvial and lacustrine, changing later to aeolian. This change was due either to a significant climate change, or the result of a decline in relief of the surrounding uplands. By the end of the Early Permian extensive dunefields occupied the basin margins with saline lakes (playas) in the basin depocentres ( Verdier 1996 ). A regional, possibly glacio-eustatic, rise in sea level later in Permian (Zechstein) times resulted in the rapid flooding (from the north) of the Southern Permian Basin. The Zechstein succession comprises a series of evaporitic cycles, and associated carbonates and muds, reflecting progressively greater evaporation and the shallowing either of the whole basin or the margins of the basin. There has been a considerable amount of interest in the Permian in recent years, with a number

The Carboniferous-Permian Dwyka Group in southern Namibia is subdivided into four upward-fining deglaciation sequences, each of which is capped by fine-grained glaciolacustrine or glaciomarine deposits. Both the second and the third deglaciation sequences are associated with mudstone units that are particularly widespread—the Ganigobis Shale Member and the Hardap Shale Member. An abundance of marine macrofossils and ichnofossils and extrabasinally derived fallout tuff horizons characterize these mudstones and provide the basis for an integrated high-resolution biostratigraphic and tephrostratigraphic framework. Juvenile magmatic zircons separated from tuff horizons at the base of the Ganigobis Shale Member (top deglaciation sequence II) yield 206 Pb/ 238 U sensitive high-resolution ion microprobe (SHRIMP) ages of 302.3 ± 2.1, 302.0 ± 3.0 Ma, and 299.5 ± 3.1 Ma, whereas a tuff associated with the upper part of the Hardap Shale Member (top deglaciation sequence III) reveals a SHRIMP age of 297.1 ± 1.8 Ma. Since macrofaunal occurrences reveal the Hardap Shale Member to be a correlative of the Gondwana-wide Eurydesma transgression, this datum is an important age calibration for a well-established global event. Tuff beds sampled next to the boundary between the glacial Dwyka Group and the postglacial Ecca Group yield SHRIMP ages of 290.9 ± 1.7 Ma and 288.5 ± 1.6 Ma, providing an age proxy for the end of the late Paleozoic ice age in southern Africa.

Abstract The separation of South America from Africa during the Early Cretaceous isolated equivalent stratigraphic sequences on both continents. This is well established for rock sequences, including flood basalts, which were deposited prior to oceanic onset; however, earlier extensional events are also recorded by the resulting intracontinental basins. Of these, the depositional area containing the Late Permian-earliest Triassic Gai-As Lake is a prime example. The aims of this paper are (1) to record facies generated within and outside the lake body and (2) to compare them with correlative bodies on the other side of the present-day South Atlantic Ocean, and (3) to record the controls of fault structures on facies architecture and lake margins. The advantages of good exposures produced by river dissection of the continental margin in northern Namibia allows good access for identifying synsedimentary fault controls on theGai-As Lake. We suggest that these can be extrapolated to correlative sequences at the conjugate South American side where exposure and thus the potential for recognition of synsedimentary structural activity is limited; consequently, the Parana "basin," commonly dealt with as an intracratonic sag basin, may be underlain by a complex of stacked rift and thermal subsidence-controlled depositional centers.

Abstract The lake sediments are preserved as two separate layers interleaved with Early Jurassic Kalkrand flood basalts (Duncan et al., 1984; Cerschutz, 1996) and are best exposed around Hardap reservoir, 15 km north of Mariental town in southwestern Namibia (Figure1). The 55-300 m thick volcano-sedimentary sequenceun conformably oversteps underlying Triassic(Stormberg) and latest Carboniferous-Early Permian(Dwyka and Ecca) sediments in the east onto latest Proterozoic-Early Cambrian (Nama) basement toward the west (Heath, 1972; Schalk and Germs,1980). The top of the sequence is defined by the erosive Cretaceous land surface with continental sediments of the Cenozoic Kalahari thermal sag basin draped thinly over the top. The 183.0 0.6 Ma to 186.0 0.8 Ma dated olivine-tholeiitic basalts (Duncanet al., 1997) of the Kalkrand Formation were extruded during extensional rifting between South America and Africa (Miller, 1992; Dingle, 1993). This was one of a series of early rifting episodes from the Permian onward (Figure 2) prior to ultimate extensional rift phases during the Early Cretaceous. The latter caused extrusion of the Etendeka-Parana flood basalts and onset of South Atlantic oceanic opening(Hawkesworth et al., 1992; Renne et al., 1996; Gladczenkoet al., 1997). Extensional tectonism was experienced in the study area along a northerly trending set of extensional167faults dipping toward the east. This is inferred (Stollhofenet al., 1998) to be conjugate to a westerly dipping break-away detachment system that connected with the more major detachment toward the west,along which oceanic opening was eventually effected(Maslanyj et al., 1992; Light et al., 1992, 1993).The Hardap area is therefore characterized by