Facies analysis suggests that Westphalian (Upper Carboniferous) Coal Measure sequences on the Isle of Arran, Scotland, were deposited in a proximal alluvial plain environment close to the basin margin. Detailed examination of well exposed coastal sections has revealed the existence of six laterally and vertically interrelated sedimentary facies. Facies 1 to 3 are interpreted as fluvial channel deposits. Low sinuosity multistorey (facies 1), low sinuosity vertically accreted (facies 2), and rare high sinuosity laterally accreted channel deposits (facies 3) are developed. Associated overbank sediments comprise the deposits of crevasse splays (facies 4), flood plains (facies 5) and shallow lakes (facies 6). In terms of the spatial distribution of facies, a relatively high proportion of fluvial channel and floodplain deposits (facies 2 and 5) occur in the more proximal sequence at Laggan compared with the more distally located sequence occurring at Corrie. Palaeocurrent measurements from fluvial channel sandstones indicate that sediment source areas and the Westphalian basin margin lay to the north and northwest. Down palaeoslope towards the southeast, normal coal-bearing Westphalian sediments formed penecontemporaneously on the Scottish mainland in Ayrshire.

A sedimentological model is presented for the proximal non-coal-bearing Westphalian sequences of Arran. This model can explain the differences observed between the Arran sediments, and contemporaneous normal coal-bearing Westphalian sediments of the Scottish mainland.

Microfossils of plant protists called acritarchs occur embedded in, mostly, authigenic chlorite cement in sandstones of the Visingsö Group (Upper Proterozoic; southern Sweden). These microfossils are commonly encrusted by a Mn-oxide layer. Similar Mn-oxide was not observed elsewhere in the sandstones, thus suggesting that certain acritarchs have played a role in the transfer and precipitation of Mn in ancient sedimentary environments. In the light of available information on the role of extant protists in biomineralization, possible mechanisms for the precipitation of Mnoxide in the Visingsö Group are discussed.

Results are presented of thin-section, SEM, X-ray and microprobe investigations on problematical phosphatic accretions (‘ Bolopora ’) from the St Tudwal's area of North Wales. The data supplement investigations made by H. J. Hofmann on the genesis of the accretions, and indicate a microbial (bacteriogenic) origin. The bacteriogenic pebble coats are of dahllite. Microbial relics suggest water–sediment interface-linked formation of the coatings under subtidal, and oxic to anoxic, environmental conditions during a sedimentary hiatus.

Several phosphatic zones are associated with the oldest remains of shelly fossils on the arctic island of Spitsbergen. The phosphate occurs as reworked nodules and layers associated with a disconformity. A gap in the acritarch biostratigraphic record supports a hiatus associated with the phosphatic zone. Palaeogeographic positions for Svalbard, both (1) as a single unit, and (2) as three isolated parts prior to Caledonian tectonism are consistent with conditions favourable to at least minimal amounts of upwelling. However, upwelling may not have been a prerequisite for development of these phosphate deposits. These phosphates were deposited in a nearshore shelf environmnt which contrasts with the outer shelf setting of many modern and recent phosphate deposits.

Geochemistry of the Lower Cambrian phosphates of Spitsbergen varies with the mode of phosphate occurrence. Concretionary phosphate clasts are chemically zoned such that their centres are enriched in P2O5 and CaO and are depleted in A12O3, SiO2, and K2O. Laminated and thinly bedded phosphate shows no chemical zonation within clasts. Phosphate cements are the most pure with respect to calcium phosphate.

This thin phosphatic zone of Svalbard is minor when compared with thicker and richer Lower Cambrian phosphate deposits, particularly those in the Soviet Union, Southeast Asia, and Australia. Coupled with the near absence of phosphate in some extensive Proterozoic to Lower Palaeozoic successions (e.g. western North America), this emphasizes the fact that widespread Lower Cambrian phosphate deposition was unevenly distributed. Althouth the Upper Proterozoic and Lower Cambrian are characterized by enhanced phosphogenesis, palaeogeographic position was also apparently critical to deposition of phosphatic sediments.

A Lower Cretaceous mixed carbonate-siliciclastic sequence is well exposed in the Zaraya Mountains in Guipuzcoa Province, northern Spain. The sequence begins with interfingering deltaic platform facies and marine patch-reef carbonates. This unit is dominated by mudstones and sandstone with minor interbeds of shallow-water carbonates (calcareous mudstones and sandstones and grainstone-packstones). A thick mixed carbonate-terrigenous unit overlies the siliciclastics and is composed principally of limestones and marls. Periodic influx of terrigenous sediments over a dominantly carbonate sea-floor gave rise to repeated cycles typical of a mixed shallow-water platform. Demise of the southerly derived deltaic input allowed the development of a mainly carbonate third unit. Large (several metres across) bioherms resulted from high in situ organic productivity (mechanical breakage of bioclasts, algal-induced precipitation, trapping and baffling of lime mudstone). The mounds grew making up a coral carbonate mound complex. This prograded to the south, towards a small backreef basin, and slightly retreated in its forereef margin. A period of tectonic instability is thought to have been responsible for the drowning of the shallow-water complex, which was unable to keep pace with relative sea-level rise.

Hornblende and muscovite within high-grade Caledonian metamorphic rocks exposed in Albert I Land (northwest Spitsbergen) display internally concordant 40Ar/39Ar age spectra providing no record of any post-Silurian thermal history. Both minerals record 420−425 Ma plateau ages indicating that relatively rapid cooling followed Silurian metamorphism. Muscovite within some metamorphic sequences exposed within the Tertiary tectonic zone of Oscar II Land (west-central Spitsbergen) displays a low-temperature 40Ar/39Ar age spectra discordance suggestive of a slight, post-Caledonian thermal disturbance. This is consistent with a post-Palaeozoic thermal overprint documented elsewhere in Oscar II Land and indicates that, at least locally, metamorphism may have accompanied the Tertiary orogeny.

Thin beds and small pods of quartz-spessartine metasediments (coticules) occur in pelites of the Gamlan Formation (Cambrian) of the Harlech Dome. The original microfabric of these sediments has been largely destroyed by recrystallization under low greenschist facies conditions. The quartz-spessartine pods occur throughout the pelites and appear to have formed by the metamorphism of diagenetic Mn-carbonate concretions. The thin beds of quartz-spessartine rock appear to have formed by the metamorphism of a protolith which was deposited rapidly and repeatedly over a wide area. Although there is no direct evidence of the nature of this protolith, the presence of altered Mn-carbonate-rich tuff beds in anchizonal mudstones of similar age in the St Tudwal's Peninsula suggests that the bedded quartz-spessartine rocks are, in fact, metamorphosed Mn-carbonate-rich tuff units. Both the bedded and podiform quartz-spessartine metasediments appear to have formed by reaction between clay minerals and Mn carbonates of earlier diagenetic origin.

Although the Mesozoic sediments of the Cleveland Basin (North Yorkshire) have generally not been strongly faulted, several approximately N–S trending faults have been identified along the coast. New seismic data from adjacent coastal waters has allowed the offshore extension to the fault system to be examined for the first time. The coastal faults from Peak (Ravenscar) to Red Cliff (Cayton Bay) are shown to form part of a linked system defining a narrow graben only some 5 km wide, the Peak Trough. Faulting has been complex, with decollement levels apparently developed in weak layers at various horizons in the Triassic and Permian strata: fault geometries and regional considerations suggest that extension has been dominant. Movement occurred intermittently from Triassic to latest Cretaceous or early Tertiary times.

An acritarch assemblage from beds beneath the Ogof Hên Formation near Carmarthen (the ‘Login beds’) resembles assemblages from the Watch Hill Grits and underlying sediments of latest Tremadoc or earliest Arenig age in the Skiddaw Group of the English Lake District. We conclude that the Login acritarch assemblage is younger than at least some part of the late Tremadoc Angelina sedgwickii Biozone, but older than the early Arenig Didymograptus deflexus Biozone. Its occurrence may therefore coincide with that of the graptolite Tetragraptus approximatus. This is of particular significance in any attempt to define an internationally correlatable base for the Arenig Series in Britain.