The Taoudeni Basin covers over 1 000 000 km(2) of the West African Craton, bounded by Pan-African orogenic belts. Four supergroups separated by craton-scale unconformities are recognized, with Neoproterozoic glaciogenic deposits occurring at the base of Supergroup 2. The Jbeliat Group occurs along a continuous, 1300-km-long, narrow belt from the Adrar region of Mauritania to the eastern limit of the Hank in Algeria and comprises thin glacial drift capped widely by periglacial polygonal structures, with more complex glacial sequences preserved in palaeo-depressions. A thicker, variously marine and continental glaciogenic succession can be found in southern parts, while fully marine, glacially influenced successions are only known from the extreme SW of the basin. The 'triad' sequence of diamictites overlain by barite-bearing 'cap' dolostones and then by green shales and/or bedded cherts (silexites) is ubiquitous and has long been used to correlate the Supergroup 1/2 boundary across the basin and into the surrounding orogenic belts. The bedded cherts commonly show a volcanic influence and are cemented by early marine calcite at their base at Adrar, Mauritania. Although fossil-based age constraints are scarce and ambiguous, regional tectonic events indicate that 'triad' deposition occurred between the Bassaride (665-655 Ma) and Dahomeyide (610-580 Ma) orogens. Recent U-Pb zircon studies of ignimbrite tuffs provide a minimum age for the glaciation of c. 600 Ma. Correlation of supergroup 2 glacial deposits with the c. 635 Ma end-Cryogenian ('Marinoan') glaciation is likely and is supported by limited carbon and strontium isotope data. Barite is commonly found within the cap carbonate and may relate to methane seepage and/or unusual oceanographic conditions after deglaciation. Several studies have attributed sequence complexity within the post-glacial succession to isostatic reequilibration. The Taoudeni Basin represents a rare Neoproterozoic example of terrestrial tillites and associated periglacial facies.

The Late Cenozoic Antalya Basin developed unconformably on a foundered basement comprising Mesozoic autochthonous carbonate platform(s) overthrust by the Lycian Nappes, the Antalya Nappes and the Alanya Massif metamorphics within the Isparta Angle, southern Turkey. The present configuration of the basin consists of three distinct parts, referred herein as the Aksu, Koprucay and Manavgat sub-basins, respectively, which are divided by the north-south-trending Kirkkavak Fault and the westward-verging Aksu Thrust.The Miocene fill of each sub-basin is characterized by thick accumulations of non-marine to marine clastics with locally developed coralgal reefs and reefal shelf carbonates. Based on lithostratigraphic and chronostratigraphic considerations, integrated with previously established data, the Miocene fill of the Antalya Basin is reorganized into nine formations and twelve members. A total of nineteen facies have been distinguished within this stratigraphic framework. The stratigraphic organization and the time and space relationships of these facies indicate contrasting styles of sedimentation characterized by several facies associations representing deposition in colluvial and alluvial fan/fan delta with coralgal reefs, reefal shallow carbonate shelf, base of fault-controlled fore reef slope and clastic open marine shelf environments in the tectonically active sub-basins. The coralgal reefs, which occur as small, isolated patch reefs developed on progradational alluvial fan/fan delta conglomerates, and the reefal shelf carbonates represent small to large scale, transgressive-regressive cycles which are closely associated with the complex interaction between sporadic influxes of coarse terrigeneous clastics derived from the tectonically active basin margins and/or related to the eustatic sea level changes during Late Burdigalian-Langhian and Late Tortonian-Messinian times.With regard to structural history, the Antalya Neogene basins exhibit contrasting behaviour according to their position within the Isparta Angle. West of Antalya, the Lycian Basin is linked to the eastwards advance of the overlying Lycian Nappes up to the Burdigalian; in the centre of the Isparta Angle, the Aksu and Koprucay sub-basins are younger (Serravalian-Tortonian) and exhibit intense deformation, reflecting west-directed compressional -events of Late Miocene to Lower Pliocene age. In contrast, the Manavgat sub-basin situated further east is only weakly deformed, and even farther east, the Ermenek and Mut basins are almost undeformed. Thus the evolution of the Neogene Antalya basins highlights the fundamental structural asymmetry of the Isparta Angle.

The Late Ordovician (Hirnantian) glaciation is examined through the North Gondwana record. This domain extended from southern high palaeo-latitudes (southeastern Mauritania, Niger) to northern lower palaeo-latitudes (Morocco, Turkey) and covered a more than 4000 km-wide section perpendicular to ice-flow lines. A major mid-Hirnantian deglaciation event subdividing the Hirnantian glaciation in two first-order cycles is recognised. As best illustrated by the glacial record in western Libya, each cycle comprises 2-3 glacial phases separated by ice-front retreats several hundreds kilometres to the south. From ice-proximal to ice-distal regions, the number of glacial surfaces differentiates (i) a continental interior with post-glacial reworking of the glacial surfaces), (ii) a glaciated continental shelf that is subdivided into inner (1-2 surfaces), middle (2-5 surfaces) and outer (a single surface related to the glacial maximum) glaciated shelves, and (iii) the non-glaciated shelf. Ice-stream-generated glacial troughs, 50-200 km in width, cross-cut these domains. These troughs are zones of preferential glacial erosion and subsequent sediment accumulation. A glacial depositional sequence, bounded by two glacial erosion surfaces, records one glacial phase. The position either within or outside a glacial trough controls the stratigraphic architecture of a glacial sequence. Glaciomarine outwash diamictites are developed at or near the maximum position of the ice-front. During ice-sheet recession, and in an ice-stream-generated trough, a relatively thin sediment cover blankets the foredeepened erosion surface. An initial rapid ice-sheet withdrawal is inferred. Marine-terminating ice fronts then evolve later into more slowly retreating, land-terminating ice fronts. In adjacent inter-stream areas where a more gradual ice-sheet recession occurred, fluvioglacial deposits prevailed. The progradation of a delta-shelf system, coeval with fluvial aggradation, that may be locally interrupted by a period of isostatic rebound, characterises the late glacial retreat to interglacial conditions. This model should facilitate the sequence stratigraphic interpretation of Late Ordovician glacial deposits and other ancient glacial successions.

The Neoproterozoic-age Mali Group of the southwestern Taoudeni Basin, NW Africa, represents, in the Walidiala Valley, a glaciogenic and post-glacial succession that brackets the Cryogenian-Ediacaran period boundary. At its base, debris flows and turbidite-like, sandy units of the Pelel Member pass upward into siltstone and shale of the Diagoma Member. These two units represent the progressive evolution from some portion of a fan delta fed by a nearby ice shelf to a more distal environment disturbed only by the occasional fallout from passing icebergs. The appearance of coarse-grained, cross-bedded sandstone beds and gravels of the overlying Tanague Member heralds a return to a shallower, fluvially influenced environment before abrupt transgression caps the glaciogenic succession. The transgressive unit consists of a regionally extensive, 2-7 m-thick, silty dolostone, the Bowal Member, which is isotopically and petrographically indistinguishable from ca. 635-Ma cap dolostone units elsewhere in NW Africa and worldwide. The Bowal Member comprises microcrystalline dolomite in turbidite-like depositional sheets disrupted by internal brecciation, fracturing and cementation by first chert and then dolomite. The stratigraphic succession in the Walidiala Valley closely resembles facies models relating to glacial retreat in a proximal glaciomarine environment affected by glacioeustasy. A large volcaniclastic debris flow has caused slumping and soft-sediment deformation within the cap dolostone of the Bowal Member. The widespread association of pyroclastic deposits with cap dolostone throughout the Taoudeni Basin implies that volcanism and deglaciation were roughly contemporaneous across a huge area. We consider that the volcaniclastic debris flow and soft-sediment deformation within the underlying Tanague Member were possibly triggered by seismic activity during deglaciation, caused by isostatic relaxation of the lithosphere. However, fitted brecciation of cap dolostone beds here and elsewhere in the world is more consistent with pervasive dolomite cementation.

The Taoudeni Basin of the West African craton contains one of the few genuine terrestrial records of a Neoproterozoic ice age. In the Adrar region of Mauritania, an extensive permafrost landscape, lithified moraines (tillites) and striated pavements are draped by a thin, generally < 5-m thick dolostone, which is lithologically and isotopically similar to other basal Ediacaran cap dolostones worldwide. In Adrar, the cap carbonate unit exhibits a complex depositional history with significant lateral facies variation related to the irregular post-glacial, topographic relief and the complex interplay between glacioeustasy and isostatic rebound. The Adrar cap carbonate package consists of one or two dolostone units, with an intervening siliciclastic package of up to 40 m thickness, and a laterally extensive, thin limestone bed that disconformably overlies the uppermost dolostone. The cap dolostone comprises mechanically laminated beds that are disrupted by fitted-brecciation, sheet cracking, tepee formation, karstic dissolution and chaotic vein networks of silica calcite and barite. The overlying thin bed of limestone breccia comprises volcaniclastic and detrital debris and authigenic barite crystals, cemented and commonly replaced by marine calcite. The close association between relative sea-level changes, glacier retreat and cap dolostone deposition across the Taoudeni Basin implies that cap dolostones formed largely over a period of similar to 10(4) years, the maximum interval over which isostatic rebound is likely to operate.Barite has been reported from identical stratigraphic levels overlying terrestrial glacial deposits throughout NW Africa and formed locally during fluid mixing on, and in cavities beneath the seafloor during late stages of the post-glacial marine transgression. Samples of barite were collected from two distant localities in the Taoudeni Basin, in Mauritania and Mali. (87)Sr/(86)Sr ratios exhibit an unusually narrow range for barite that closely matches contemporaneous seawater (87)Sr/(86)Sr (0.7077-8). Barite delta(34)S values range widely between 20 parts per thousand and 45 parts per thousand CDT, which indicates that sulphate derived from seawater and was subsequently modified by microbially mediated sulphate reduction. The consistent stratigraphic level and irregular distribution of barite deposits are consistent with a sedimentary exhalative origin for the barite, whereby Ba-rich fluids from shallow locations within the rock pile interacted with sulphate-bearing seawater; a hydrothermal origin for these fluids can be excluded. Isotopic constraints and the association of barite with terrestrial glacial deposits across the West African craton suggest that methane seepage from underlying permafrost may be one possible mechanism for Ba sequestration. The occurrence of seafloor barite precipitates at the contact between cap dolostones and overlying post-glacial limestones worldwide implies that changes in ocean composition, in particular increases in the sulphate content of ambient seawater provided an overriding control on barite mineralisation. (c) 2006 Elsevier B.V. All rights reserved.

This paper attempts to describe the Neoproterozoic–Cambrian lithostratigraphic successions occurring on the West African craton and in the surrounding Pan-African fold belts, with special reference to glacial or glacially influenced deposits. It provides a brief synthesis of these terrains in order to propose inter-regional correlations, and to place the glacial events already described in the literature within the tectonic framework of this part of the world. Correlations are based on facies associations and isotopic databases, and supported by the occurrence of glacial deposits when these are ascribed to continental-scale glaciation. As expected, there is a diachronism of the main tectonic events around the craton when the mobile belts display a roughly similar overall facies trend reflecting the successive stages of the Pan-African orogenic cycle from rifting to collision. Contrary to most of the Neoproterozoic glacial strata elsewhere, which consist generally of marine diamictites preserved in marginal basins, West Africa displays the cratonic counterpart (tillites and associated terrestrial facies) deposited on exposed land surface by continental ice sheets. Lithostratigraphic correlations and a combination of relative dates on sedimentary rocks and on tectonic markers show that a major West African glaciation occurred between 630 and 610Ma and can be correlated with the Marinoan ice age. This major climatic event is contemporaneous with the final stages of the Pan-African orogenic cycle. Under favourable climatic conditions (mid to high latitudes), the presence of surging reliefs at the rim of a wide cratonic platform may account for the development of the West African Marinoan ice sheet. The diachronism around the craton of collision-surrection events may also account for the occurrence of unrelated local mountain-type glaciation that could be mistaken with the craton-scale glaciation.

Abstract The Manavgat Basin is a northwest-southeast oriented basin that developed on the eastern side of the Isparta Angle, south of the Late Eocene thrust belt of the western Taurides. The Miocene fill of the basin lies unconformably on an imbricated basement, comprising a Mesozoic para-authocthonous carbonate platform overthrust by the Antalya Nappes and Alanya Massif metamorphics. The sedimentary fill is represented by clasticdominated deposits consisting of, in ascending order, a conglomeratic wedge, reefal shelf carbonates, limy mudstones, and calciturbidites with subordinate breccias and conglomerates. Process-oriented facies analysis of the basin fill indicates a variety of depositional environments ranging from fluvial/alluvial fan and fan-delta complexes through reefal carbonate shelf and forereef slope to slope fan and basin floor. Fluvial/alluvial fan and fan-delta deposits are Burdigalian-Early Langhian in age and represent the initial conglomeratic valley-fill sedimentation during a relative sea-level rise balanced by important sediment supply from relief in the north-northeast hinterland. The continuous relative sea-level rise and a decreasing rate of sediment supply allowed the deposition of transgressive reefal shelf carbonates of Langhian age. Tectonic activity demonstrated by synsedimentary faults resulted in block faulting of the narrow carbonate shelf and foundering of the basin. The rest of the sedimentation consists of the fill of newly created accommodation space. The overall coarsening-upward succession consists of Upper Langhian-Serravallian limy mudstones-calciturbidites and debris flows, overlain by Tortonian coarse-grained fan-delta deposits. The gravity induced character of most of this progradational wedge implies a progressive uplift of the hinterland.

Late Quaternary glacial features have been found in the Central Taurid Mountains, in U-shaped valleys located at an altitude of more than 2000 m and surrounded by mountain ranges reaching 2850 m. No present day active glaciers exist in this area where the snowline elevation lies at about 3500 m. The Namaras Valley and its tributary Susam Valley are characterized by coarse loose material forming chaotic knob-and-kettle topography. Mounds, 1-10 m high and 10-30 m wide, are separated by 5-30 m wide, several meters deep, irregular depressions. The upper surfaces of the mounds are covered by angular to subangular limestone pebbles and blocks and internal sediments show a typical diamicton appearance with pebbles suspended in a muddy to sandy matrix. These chaotic structures are interpreted as hummocky disintegration moraines from former active glaciers. Successive cross-valley morainic ridges, up to 200 m high and several hundreds of meters long, limit the down-valley extension of these hummocks, and are interpreted as ice-marginal moraines. In the tributary Susam Valley, part of the coarse loose material forms a 200-250 m long and 90-120 m wide tongue-shaped structure with successive arcuate ridges and furrows at its down-valley reach. This structure, which is connected upward to a talus slope and perched cirque, ressembles the morphology of a periglacial rockglacier but is interpreted as the disintegration moraine controlled by small periodic retreat and readvance of the last active ice-front in this region. (C) 1999 Elsevier Science Ltd. All rights reserved.

Late Ordovician siliciclastic glacial and related deposits on the North Gondwana continental shelf comprise striking incised features referred to as large-scale channel-fill structures. These are described from exposures and aerial photographs in two areas (Adrar and Hodh) in Mauritania. The channel-fill structures an up to several kilometres in length and several hundred metres wide. They are slightly sinuous narrow sandstone bodies deeply incised into the Late Ordovician glacial drift and the Cambro-Ordovician bedrock. Palaeogeographical reconstructions indicate that these structures were located in the ice-marginal zone. They are preferentially oriented parallel to palaeo-ice-flow directions. Sedimentary facies analysis reveals three vertically stacked architectural units infilling a U-shaped erosional basal unconformity. Unit 1 is thin and made up of conglomeratic sandstones of various origins comprising debris-flows, deltaic-like progradational foresets and trough cross-stratified sands. In Adrar, architectural unit 2 shows sheet-like, evenly laminated, fine- to medium-grained, well sorted sandstones characteristic of a high-energy marine environment. In contrast, in the Hodh area, unit 2 displays vertically stacked successions of coarse-grained sandstones that indicate high-discharge sediment-laden flows; these are interpreted as meltwater sediments. In both Adrar and Hodh, architectural unit 3 is made up of gravelly coarse-grained, trough cross-stratified sandstone emplaced in a braided, low sinuosity fluvial environment. The three-stage infilling history and the palaeogeographic location combined with size and shape criteria make it possible to compare the channel-fill structures with Pleistocene tunnel-valleys found in areas of low-relief in cool temperate and low Arctic zones. Such features are incised by high-pressure subglacial meltwater and later infilled by proglacial to postglacial deposits. Based on this comparison, architectural unit 1 represents subglacial or proglacial outwash, high sediment discharge in unit 2 took place in a proglacial environment in the Hodh area while an isostatically downwarped shelf was responsible for a marine incursion in the Adrar channels, and deposits in unit 3 are fluvial postglacial sediments. Identification of preserved channel-fill structures may be useful in reconstructing Late Ordovician ice-sheet dynamics. (C) 1998 Elsevier Science B.V. All rights reserved.

The Haymana basin in central Anatolia (Turkey) formed on a Late Cretaceous to Middle Eocene fore-arc accretionary wedge. A sequential model is proposed for the 1-km-thick Lutetian Yamak turbidite complex (YTC) which is the youngest paleotectonic unit of the basin. The YTC represents a prograding submarine fan subdivided into three depositional sequences (DS), each several hundred meters thick. Each depositional sequence consists of a turbidite system (TS), with sandstone and conglomeratic sandstone beds alternating with mudstones, overlain by basin plain mudstones. In each turbidite system, the sandstone and mudstone sequential organization allows the distinction of smaller subdivisions, namely, basic sequences (BS) and basic units (BU), with each basic sequence being composed of several basic units. This subdivision, associated with a two-dimensional geometric reconstruction of the YTC, leads to a better understanding of the evolution in time and space of the submarine fan system. Lower to middle fan depositional lobes, and upper fan and slope channels, are represented. As a whole, the YTC progressed from a sand-poor to a sand-rich system. Depositional sequences (DS) of the YTC may correspond to third-order sea-level cycles of tectonic origin. Accordingly, fourth- and fifth-order cycles might be proposed for the BS and BU, respectively. However, partly because of the limited extent of exposures, the allocyclic origin of these finer subdivisions remains problematic.

The Upper Permian Champenay Formation was deposited in a series of continental basins in northeastern France. Within the lower part of this formation, there is a sandstone of controversial origin. In the Champenay Basin, this sandstone of the Champenay Formation is exposed in three quarries between the towns of Champenay and Belval. In these quarries the sandstone is composed of deposits from deltaic, lacustrine, beach, alluvial, and eolian environments. Interpretation of these deposits suggests that the Champenay Basin was occupied by a lake, and that deltaic sediments prograded into this lake from the southeast. Relative changes in lake level resulted in the development of bounding surfaces among the deltaic sediments. Debris flows, ephemeral sheet flows, beach deposits, and eolian dunes were also present along the southern margin of this lake. The eolian dunes were crescentic in shape and migrated to the northwest. Sediment entered the southern margin of the Champenay Basin and was then redistributed and reworked by deltaic, lacustrine, beach, and eolian processes.

Lower Cretaceous (Valanginian to Albian) strata of the southwestern Eromanga and Carpentaria basins of central and northern Australia, respectively, provide evidence of strongly seasonal climates at high paleolatitudes. These include dispersed clasts (lonestones) in fine sediments and pseudomorphs of calcite after ikaite (glendonites), the latter being known to form only at temperatures below about 7° C. Rafting is regarded as the transport mechanism for clasts up to boulder size (lonestones) enclosed within dark mudrocks; this interpretation rests on rare occurrences of penetration by clasts into substrate layers. Driftwood and large floating algae are eliminated as possible rafts because fossil wood is found mainly concentrated in nearshore areas of the basins and large algal masses have not been observed. Rafting by icebergs is considered unlikely in view of the global lack of tillites and related glacial deposits of this age. Our interpretation is that seasonal ice, formed in winter along stream courses and strandlines, incorporated clasts which, during the melt season, were dropped into muddy sediments in both basins. Eromanga fine-sediment and lonestone clasts in places were reworked subsequently by storm activity, producing lag concentrations of large clasts and associated sand lenses, both lying above local erosion surfaces. In the Carpentaria Basin, local dumping of sediment from raft surfaces resulted in accumulation of pods of small clasts. Three zones can be identified for the Early Cretaceous climate of eastern Australia: (1) a very cold southern region, at latitudes above about 72 ° S, characterized by meteoric waters possibly originating as Antarctic glacial meltwaters; (2) a zone of strongly seasonal climates, with freezing winters and warm summers, between about 72° and 53° S. Lat.; and (3) a mid-latitude zone (below about 50° S. Lat.), where freezing temperatures were not common. However, owing to scant biostratigraphic control on the successions, the time span of specific climates in both the cold and the seasonal zones cannot be determined and probably existed only for short intervals.

Le secteur étudié, situé à proximité de la frontière mauritano-malienne, comporte de nombreux affleurements de grès argileux à blocaux à caractères glaciaires (diamictites ou tillites) dont l'interprétation sédimentologique et la position stratigraphique sont longtemps restées incertaines. En fait ils appartiennent tous à un même ensemble glaciaire, le groupe du Bakoye, dans lequel ils constituent trois niveaux glaciogéniques distincts (deux tillites terrestres et une diamictite marine) séparés par des faciès de remaniement gréso-argileux. Ce groupe, épais de 250 m, représente la période glaciaire du Précambrien terminal déjà mise en évidence dans d'autres parties du bassin de Taoudéni, et fournit un certain nombre de données complémentaires quant à la paléogéographie de l'inlandsis qui a recouvert à cette époque une grande partie de l'Ouest-Africain. Les formations encaissantes (groupes de la Kolimbiné et de Nioro) sont également étudiées et des éléments nouveaux sont apportés concernant le mode de mise en place des dolérites formant le grand massif du Kaarta et les minéralisations induites dans les roches encaissantes.