There are two thrust systems in the Southwest Pyrenees: a NW-SE trending, thin-skin system exposed in the post-Triassic cover and a larger, thick-skin system of NE-SW thrusts in the Palaeozoic basement. The ‘cover’ thrust system propagated and migrated both southward and westward in response to the non-orthogonal collision of Iberia with Europe during Palaeogene mountain building. The ‘basement’ thrust system is interpreted to be a longer-lived structure, initiated during the extensional tectonic regime in mid Cretaceous time, and inverted during the main episode of Pyrenean collision. A model in which interaction of the two thrust systems controlled the timing and magnitude of thrust-induced, flexural subsidence is presented. The development of the basement thrust system caused regional subsidence along the South Pyrenean foreland margin that was subsequently halted by local uplift associated with the west-migratingcover thrust system.

The Yangtze Platform (Yangtze Palaeoplate) drifted into the area of southern China following late Silurian tectonism. In late Palaeozoic to early Mesozoic time the Yangtze Platform was subjected to strong extensional movements in its southeastern region within Yunnan, Guizhou, Guangxi and Hunan provinces, and along its northwestern margin in the Songpan-Ganzi area. Taphrogenesis (intracontinental extension) began in Devonian times, climaxed with the late Permian eruption of the Emeishan basalts, and ended in mid Triassic times. Therefore, the senior author (LZL) has named this extension the ‘Emei Taphrogenesis’, a phenomenon that was constrained by the neighbouring tectonic units of the Yangtze Platform. The platform has been substantially affected by the early Palaeozoic south China fold zone along its eastern margin, and by the late Palaeozoic opening of the Tethys Ocean on the northwestern margin. This paper delineates the tectonic patterns associated with the Emei Taphrogenesis.

The western part of the Fintona Block is divided into four fault-bounded segments that contain red-bed sediments formerly assigned to the Lower Old Red Sandstone.Dating by miospores indicates the presence of deposits of early Devonian age in the Irvinestown Segment, late Viséan–early Silesian age in the Tempo–Lisbellaw Segment, and late Viséan–early Silesian and late Silesian ages in the Milltown Segment. Northward migration of the early Carboniferous marine transgression in the northern part of Ireland coincided with the sequential propagation of back-stepping faults and resulted in the development of diachronous facies belts between late Courceyan and Arundian times. Tectonic uplift, of a possible southwesterly extension of the Tyrone Igneous Complex, gave rise to the deposition of Asbian to Pendleian red-beds to the south of a massif. An interface between these red-beds and contemporaneous marine sediments farther to the south is recognized and dated. A new non-marine basin, containing Brigantian and Pendleian red-beds, also developed to the north of the massif A waterlogged floodplain that developed during Westphalian A times may be coeval with more widespread coal-bearing sequences elsewhere in Ireland. Alluvial fans prograded southwards over this plain during Westphalian B times when faults bordering a northern landmass were reactivated.

New radiometric age data are reported for alkaline centres in southern Namibia, and are discussed together with published age data in terms of models put forward to account for post-Karoo (Mesozoic–Recent) alkaline magmatism within the African plate. Agreement between K–Ar and Rb–Sr ages indicate emplacement of the Dicker Willem carbonatite in southern Namibia at 49 ± 1 Ma. Alkaline rocks associated with the Gross Brukkaros volcano show a discordant radiometric age pattern, but the best estimate for the age of this complex is 77 ± 2 Ma, similar to that obtained for the neighbouring Gibeon carbonatite-kimberlite province. The Dicker Willem carbonatite is therefore younger than the Luderitz alkaline province (133 ± 2 Ma), and the Gross Brukkaros volcano, but is older than the Klinghardt phonolite field (29–37 Ma). The new age data argue against a distinct periodicity in alkaline igneous activity in southern Africa, thereby ruling out possible controls by episodic marginal upwarping of the subcontinent. Although the available age data do not appear to be consistent with the passage of one or even two hotspots under southern Namibia, it is argued that the surface expression of hotspots under continents may be so large and overlapping that within-plate magmatism attributed to these thermal anomalies need not necessarily be confined to narrow linear belts or show an age progression. The role of hotspots in continental alkaline magmatism is most likely one of melt generation, while local crustal structure probably controls the distribution and timing of eruption. Major tectonic boundaries in the Precambrian basement underlying southern Namibia seem to have controlled the development of Tertiary alkaline centres in that region.

A new early Cambrian sponge of sphinctozoan organization named Polythalamia americana nov. gen. et sp. is described from Nevada and Alaska, U.S.A. P. americana nov. gen. et sp. shows little resemblance to other Cambrian reported sphinctozoans, but is similar to late Palaeozoic to early Mesozoic forms from Europe and Asia, e.g. Stylothalamia and Amblysiphonella. The polyphyletic origin of sphinctozoans based upon spicule criteria from younger examples is therefore corroborated by the varied morphology and clearly widespread palaeogeographic distribution of Cambrian forms, which were hitherto recognized only from Australia. P. americana nov. gen. et sp. possesses a relatively small, globular multi-chambered calcareous skeleton, with thin but densely perforate walls and a central retrosiphonate, perforate spongocoel. The skeleton is composed of an irregular microstructure of unknown, but probable calcitic, original mineralogy. There are no spicules or primary internal structures, but secondary vesicular filling tissue is present. The pore organization, however, it directly comparable to archaeocyaths, e.g. coscinocyathines, and this character is taken to be the only synapomorphy available for taxonomic and phylogenetic purposes. Indeed, P. americana nov. gen. et sp. is closely associated with a diverse archaeocyath assemblage and draws attention to morphological similarities between some archaeocyaths and sphinctozoans, thus questioning the criteria at present used to distinguish between these groups. Accordingly, a list of nomenclatural synonymies is given to aid comparison. Coscinocyathine archaeocyaths possess chambered juvenile stages and P. americana nov. gen. et sp. is suggested to represent an aspiculate lineage of sphinctozoan grade which may be derived from forms such as Clathricoscinus by neoteny. It appears that at least three clades of sphinctozoan-grade calcified sponges were present by end of early Cambrian time and their occurrence in association with island arcs of the palaeopacific rim is confirmed.

An exceptionally well-preserved synsedimentary deformation feature is described from uppermost Miocene fluvio-lacustrine coastal plain sediments, exposed in lignite mines of the Lower Rhine Basin, Germany. The feature is interpreted as a complex, multi-stage channel-bank collapse structure. Rotational slumping of bank material into the channel along two failure surfaces extending below the channel toe generated a series ofminor compressional ‘thrust/backthrust’ structures within the muddy channel-fill sediments. A reconstruction of the failure event is proposed which is linked toa lowering of river stage and subsequent channel abandonment. The accurate description of this unusually well-preserved channel-bank collapse structure may have general application in the interpretation of similar, but less-well-exposed-preserved phenomena elsewhere.

Investigations of the March Gravels of Northam Pit, Eye, Cambridgeshire, have provided previously undescribed molluscan, ostracod and foraminiferal faunas together with pollen spectra, which enable a detailed palaeoenvironmental synthesis to be developed. The sediments were laid down in brackish-water conditions and a temperate environment, during a Late Pleistocene temperate stage.