Abstract The focus of this chapter is the West Congo Supergroup in the West Congo Belt (WCB), which extends along the western margin of the Congo Craton from Gabon in the north to northern Angola in the south, and the Lindi/Ubangi Supergroup of the Lindian and Fouroumbala – Bakouma Basins exposed on the northern margin of the craton. In both regions, up to two distinct diamictite horizons have been recognized, the younger of which is often associated with carbonate rocks. Geochronological constraints are generally rather poor, many of the deposits lack modern sedimentological analysis, and the glacial versus non-glacial genesis of the diamictites is a matter of debate in the literature. However, recent studies suggest a periglacial influence of diamictite deposition, particularly for the sequences in the WCB. The stratigraphy of the various basins is described, available geochemical and geochronological information collated, and recent work regarding the periglacial nature of the diamictites discussed. Finally, an updated chronostratigraphic correlation between the basins is presented. However, much more work is required, particularly in the Neoproterozoic basins on the northern margin of the Congo Craton, and more accurate geochronological constraints are required before the Neoproterozoic palaeogeography and depositional environments of the western and northern Congo Craton can be fully understood.

Abstract The Carboniferous (359.2–299 Ma, Gradstein et al. 2004 ) succession of Central Europe records one of the most important time periods with respect to European geology, since it marks the final collision of Gondwana with the northern continent of Laurussia (i.e. Laurentia, Baltica and Avalonia). Oblique convergence resulted in collisional processes which created a mountain belt extending from Russia, through western Europe and into North America. The climax of the Variscan Orogeny was the formation of the supercontinent Pangaea leaving a relict Palaeo-tethys to the east ( Scotese & Langford 1995 ) (Fig. 9.1 ). The Variscan belt is a broad (c. 1000 km) complex curvilinear feature extending across Europe and marking the zones of Variscan-age deformation (Figs 9.2 & 9.3 ). The final phase of Variscan activity was also a period of terrane mobility and tectonic instability in the Central European region with sinistral wrench faulting causing widespread rifting of the northern European crust ( Pegrum 1984 a, b ; Ziegler 1990 ). The Carboniferous succession in Central Europe is generally dominated by marine sediments (both clastic and carbonate) in the lower part of the succession¨ The clastic sediments tend to be deeper-water shelf or turbiditic successions, although in some areas (e.g. Belgium, northern Germany) limestones are locally important or even dominant, particularly during the Tournaisian and Visean. In late Carboniferous times, successions are predominantly continental with some coal-bearing units being deposited (particularly in Westphalian times). An exception to the dominantly sedimentary record is provided

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

Abstract Neoproterozoic to Late Palaeozoic times saw the break-up of the supercontinent Rodinia, and the subsequent construction of Pangaea. The intervening time period involved major redistribution of continents and continental fragments, and various palaeogeographical models have been proposed for this period. The principal differences between these models are with regard to the drift history of Gondwana, the timing of collision between northern Africa and Laurussia, and formation of Pangaea. Palaeomagnetic evidence provides basically two contrasting models for the Ordovician to Late Devonian apparent polar wander (APW) path for Gondwana involving either rapid north and southward movement of this continent, or gradual northward drift throughout Palaeozoic time. In contrast, palaeobiogeographical models suggest contact between Laurussia and Gondwana as early as mid-Devonian time with the continents basically remaining in this configuration until break-up of Pangaea in the Mesozoic era. This is in conflict, however, with most palaeomagnetic data, which demonstrate that in Late Devonian time, north Africa and the European margin of Laurussia were separated by an ocean of at least 3000 km width. This is also in agreement with the geological record of present-day southern Europe, which argues against any collision of northern Africa with Europe in Devonian time. With regard to formation of Laurussia, however, palaeobiogeographical and palaeomagnetic data are in excellent agreement that by mid-Devonian time the oceanic basins separating Baltica, Laurentia, Gondwana-derived Avalonia and the Armorican Terrane Assemblage (ATA) had all closed. Palaeomagnetic and geological data are also in agreement that the Palaeozoic basement rocks of the European Alpine realm formed an independent microplate, which was situated to the south of Laurussia. In Late Silurian times it was separated by an ocean of c. 1000 km, and by Late Devonian time was approaching the southern Laurussian margin. According to palaeomagnetic data, the northern margin of Gondwana was still further to the south in Late Devonian time, and according to the geological record in southern Europe, the main continent–continent collision of northern Africa with European Laurussia and closure of the intervening ocean occurred in Late Carboniferous times. Location of this suture is situated to the south of the Palaeozoic alpine units (e.g. the Greywacke zone, Carnic Alps, Sardinia and Sicily), but has been obscured by younger deformational events and cannot be precisely positioned. Assessing available evidence and as discussed in the text, it is proposed that the most likely scenario is that the northern margin of Gondwana drifted gradually northwards from Ordovician to Late Carboniferous times when it collided with Laurussia, resulting in formation of Pangaea.