Two new genera and species of Middle Cambrian sphinctozoans, Jawonya gurumal and Wagima galbanyin, are described from the Tindall Limestone of the Daly Basin, Northern Territory, within continental platform successions of the northern Australian craton. They are ambisiphonate sebargasiids, coeval with the island-arc shelf fauna from the Ordian Stage of western New South Wales. Additionally, a new Early Cambrian (Atdabanian equivalent) species, ?Jawonya tiro, displaying some sphinctozoan and some archaeocyathan features, is documented from the Ajax Limestone of the Arrowie Basin, South Australia. It is tentatively regarded as the oldest known sphinctozoan, but raises the possibility of the derivation of sphinctozoans from archaeocyaths. A brief review charts the Early–Middle Palaeozoic history of the sphinctozoans. The use of filling tissue type as a family-level criterion in sphinctozoan classification needs some reappraisal, as some types are of secondary origin.

Numerous acritarchs and stromatolites have been discovered and studied from the Proterozoic Datian Formation of the Kunyang Group and the Meidang Formation of the Dongchuan Group in Sichuan–Yunnan area, southwestern China, and more than 80 oxygen isotope data have been obtained from the sediments. Based on size-range and variation of non-filamentous acritarchs, the development of columnar stromatolites and the 18O/16O values of stromatolitic and nonstromatolitic carbonate rocks, the author proposes, for the first time, a palaeoenvironmental framework of the Kangdian area during Datian–Meidang time.

Although the usefulness of Precambrian acritarchs and oxygen isotope values in palaeoenvironmental analysis of a sedimentary basin is just beginning to be understood, it is evident that these data are an important basis for palaeoenvironmental studies.

Early petrofabric studies of quartz c axis preferred orientation within the Tarskavaig Nappe, located at the southern end of the Moine thrust zone, have been interpreted as indicating that structures within the nappe have been produced by tectonic movements acting at right angles to those responsible for formation of structures within the overlying, but immediately adjacent, Moine Nappe. Such a dramatic contrast in inferred transport direction has not been recognized within the rest of the thrust zone.

Re-examination of the microstructures and c axis fabrics within mylonitic metasediments from the western part of the Tarskavaig Nappe has revealed that these tectonites are characterized by maximum principal extension axes which trend sub-parallel to the WNW-trending Moine thrust zone transport direction. Later folding has reorientated and modified these structures within the eastern part of the nappe producing fabrics which have erroneously been taken to indicate a transport direction orientated sub-perpendicular to that of the rest of the Moine thrust zone.

WNW-trending maximum principal extension axes and WNW-directed overthrust senses are indicated by microstructures within schists from the adjacent Moine Nappe, suggesting that structures within both the Tarskavaig and Moine nappes may be associated with a common west-northwest transport direction.

Essentially coaxial (pure shear) strain paths (indicated by symmetrical c axis fabrics) dominate the internal parts of the Tarskavaig Nappe. Close to the base of the nappe, non-coaxial strain paths, originally associated with WNW-directed overthrusting, are indicated by asymmetrical c axis fabrics and oblique grain shape alignments. Strain compatibility considerations indicate that the lower kinematic domain (which must either be contemporaneous with, or later than, formation of the upper domain) must be characterized by a combination of pure and simple shear deformation.

Previous views on the relationship between the thick continental deposits of the Dingle Group and the older fossiliferous Silurian rocks of the Dunquin Group are briefly reviewed. Detailed field evidence is presented showing that in the coastal sections of Coosgorrib, Coosglass, and Coosshaun there is faulting between the two groups. The same situation obtains at the northern end of the Great Blasket island. Fortunately inland exposures are sufficient to show that there is stratigraphical continuity from the lower Ludfordian (Ludlow) beds of the Croaghmarhin Formation, at the top of the Dunquin Group, into the purple siltstones of the Dingle Group. The Dingle Group is followed uncomformably by Upper Old Red Sandstone (essentially Upper Devonian).

Peak metamorphic conditions (up to sillimanite grade) in a unit of rocks beneath the evolving Kalak Nappe Complex (Finnmarkian Caledonides) developed prior to its incorporation as a nappe within the complex. The presence of displacement textures in peak metamorphic por-phyroblasts indicates that they grew in a hydrostatic stress regime and thus that the emplacement of tectonically higher units caused little or no deviatoric stress in the footwall rocks except close to the thrust plane.

The developing geotherm in the incipient nappe was disrupted by the onset of thrusting (D2 deformation), which placed hot rocks on colder rocks. This led to the cessation of prograde metamorphism and accounts for the ubiquitous association of nappe emplacement and the meta morphic peak. Later deformation (D3/D4) occurred at lower grades (biotite/chlorite). Consideration of nappe translation rates and the likely erosion/cooling rates indicates that nappe movements must have occurred ‘continuously out-of-sequence’ within the Kalak Nappe Complex.

Archaean sedimentary and volcanic successions in the Lalla Rookh Basin and c. 2950 Ma old Whim Creek Belt in the Pilbara Block, Western Australia, were deposited in basins with roughly the same configuration as their present outcrop. Basins were fault-bounded and developed in an ensialic setting, overlying older (3500 to 3300 Ma old); deformed and metamorphosed supracrustal rocks and granitoids. The basin margin faults are now part of a pattern of strike–slip faults which were active during the later stages of regional batholith emplacement. In both cases, structural patterns and style of basin filling are similar to younger basins related to strike–slip faulting. The Lalla Rookh Basin was dominated by coarse clastic sedimentation, comprising alluvial–fan, braided–stream, fan–delta and lacustrine facies. The Whim Creek Belt contains bimodal volcanics and clastic sediments, which comprise alluvial, subaqueous fanglomerate, submarine-fan and basinal facies. Regional strike–slip faulting and the development of the Lalla Rookh Basin and Whim Creek Belt, in response to externally imposed deformation, records an important step in the cratonization of the Pilbara Block. Late Archaean sedimentary basins, dominated by coarse clastic facies and situated adjacent to major strike–slip faults, in other cratons may have a similar origin.

The Lower Carboniferous (Asbian) sediments and volcanics of the Pettycur region in Fife, Scotland, yield several important anatomically preserved floras including that from the famous ‘Pettycur Limestone’. The plant fossils are preserved as calcareous permineralizations and fusain within limestone blocks which occur at the base of basaltic lava flows or within pyroclastic sequences. The geology and sedimentology of these plant deposits have been investigated, and it is demonstrated that a number of plant-bearing facies can be recognized which reflect different modes of transport, deposition and fossilization. Of these facies the ‘Pettycur Limestone’ is the most well known. The lithology is composed of a distinct assemblage dominated by lycopods and the pteridosperm, Heterangium. Other assemblages include a limestone dominated by zygopterid ferns which are frequently fusainized and the Kingswood Limestone which contains a completely different flora to that at Pettycur, being dominated by pteridosperms, other gymnosperms and the lycopod Oxroadia. Each sediment type is characterized by a distinct mineralization history of the plants reflecting different sites of fossilization.

A hypothesis concerning the original ecology of the plant assemblages within the basaltic volcanic terrain is proposed. It is suggested that the Pettycur Limestone represents an established original peat within which the plants were permineralized. The zygopterid ferns occupied sites which were susceptible to wildfire and did not establish long-lived peat-forming communities. The Kingswood flora was established in a region where plants were prone to fire and then subsequently transported into an area of limestone deposition along with unburnt plant fragments. This flora was separated by space and/or time from the Pettycur floras. Lakes developed on lava surfaces and provided sites of fossilization for plant fragments as compressions.

Evaporites within Upper Triassic to Lower Cretaceous sequences in the Atacama region of northern Chile are interpreted as the deposits of continental and coastal saline lakes. Halite casts and finely laminated calcareous evaporites, intercalated with alluvial and fluvial sediments, are probably playa lake deposits. These continental evaporites have been recognized in Upper Triassic alluvial sediments (Cifuncho Formation), in Upper Triassic–Lower Jurassic braided river deposits (basal unit of the Pan de Azúcar Formation), and within a sequence of Lower Cretaceous aeolian, alluvial and playa lake mudflat sediments (Quebrada Monardes Formation). Lower Cretaceous evaporites between marine limestones (Lautaro Formation) and continental redbeds (Quebrada Monardes Formation) were probably deposited in coastal saline lagoons, produced during a regionally extensive marine regression.

These sequences, and other similar successions in northern Chile, provide a record of almost continuous evaporite deposition, and hence of arid to semi-arid conditions, since Upper Triassic times. These conditions were primarily the result of a constant latitudinal position within the subtropical zone. A contributary factor was the geographical position of the area, initially on the west coast of Gondwanaland and subsequently on the coast of South America, with cold, northward-flowing ocean currents and offshore winds.

In every correlation exercise the diachroneity of the lithostratigraphic boundaries determines the discrepancy between lithostratigraphic correlation and time-correlation. Here it is shown that diachroneity varies in degree as a simple function of the direction in which correlation is made, and hence that stratigraphic correlation must take that direction into account. When the direction of correlation is not known, a sound strategy for time-correlation of lithostratigraphic boundaries is to assume that each is at its most diachronous.

The Armorican Quartzite (Lower Ordovician) is a very extensive sandstone body found throughout a large part of Iberia and Brittany; similar quartzites are present in north Africa and elsewhere. In Iberia it generally lies unconformably on a thick, folded, late Precambrian to Cambrian turbidite sequence (the Complexo Xisto-Grauváquico (CXG)), but there are some places where the quartzite has a conformable relationship with the underlying CXG. Where conformable the whole succession shows varied facies sequences including: (i) a regressive mud–sand sequence as a precursor to the main quartzite development, (ii) submarine fan sediments of the CXG passing up into slope and then shallow marine facies, or (iii) fluvially influenced breccio-conglomerates of a marginal fan delta passing up into shallow marine sediments.

The inferred development of alluvial fans associated with fan deltas prograding into shallow marine environments implies steep slopes and the likelihood that faulting controlled some of the uplift. The mozaic pattern of differential uplift and subsidence throughout the region suggests that the CXG was affected by local block movements rather than by regional folding.

The presence of upstanding blocks during the initial sedimentation of the Armorican Quartzite suggests that the quartz sand might have been derived from multiple sources dispersed throughout the area rather than from sources along a single shoreline at the margin of the depositional area.

Clay minerals from Middle Jurassic lagoonal mudrocks, siltstones and silty fine-grained sandstones of the upper Great Estuarine Group (Bathonian) are divided into four assemblages. Assemblage 1, the most common assemblage, is rich in mixed-layer illite–smectite with attendant illite and kaolinite. Assemblage 2 is dominated by smectitic clay. These assemblages are indicative of primary Jurassic deposition. Illite and kaolinite were probably derived from the weathering of older rocks and soils in the basin hinterland and were deposited in the lagoons as river-borne detritus. The majority of smectite and mixed-layer illite–smectite is interpreted as the argillization product of Jurassic volcanic dust, also deposited in the lagoons by rivers. Near major Tertiary igneous intrusions these depositional clay mineral assemblages have been altered. Assemblage 3 contains smectite-poor mixed-layer illite–smectite, whilst Assemblage 4 contains no smectitic clay at all. Destruction of smectite interlayers occurred at relatively shallow burial depths (< 2500 m) due to enhanced geothermal gradients and local convective hot-water circulation cells associated with the major Tertiary igneous intrusions.

An encysted portion of a crustoid stolotheca of Graptoblastoides sp. has revealed possible cellular tissue, but no gross zooidal morphology. Two explanations are suggested: one regarding the cellular complex as remnants of entrapped soft parts; the other, less likely, indicating a local disturbance in the secretion of the blastocrypt material. The cellular tissue is figured and described, and the opportunity is taken to review the extent of knowledge with respect to graptolite soft parts, and to compare the structures described with features of extant Rhabdopleura species.

The Castores and probably the Santa Rosa plutons of north-west Isla Navarino, southern Chile, have been emplaced by in situ diapirism into metasedimentary rocks of the Upper Jurassic (?)–Lower Cretaceous Yaghan Formation. For the former, this model is consistent with the concentric foliation paralleling the margin of the pluton and the foliation and stratification planes in the metamorphic aureole. Only the southern part of the Santa Rosa Pluton is preserved, and it has some structures similar to those of the Castores Pluton, which can also be interpreted as produced by an inflating diapir. The main intrusive rocks of these plutons are quartz-monzodiorites and quartz-diorites with synmagmatic foliation. They were preceded by minor bodies of hornblende gabbros, and followed by dykes and small bodies of non-foliated granodiorites. Non-foliated to weakly foliated granodiorites, forming the centre of the Castores Pluton, probably represent a younger intrusive pulse.

Twelve K–Ar mineral dates from 10 specimens of plutonic rocks, interpreted as near crystallization ages, span the period 80–90 Ma. These dates do not show the sequence of intrusion of the different rock-types, which may suggest that all of them were intruded and cooled in a short period of time. The timing of emplacement of these plutons in relation to tectonism is difficult to determine; however, a post-tectonic emplacement for at least the Castores Pluton, is proposed.

Large-scale sedimentary structures are described from the Lough Muck Formation (Wenlock) of north Galway, Ireland. They consist of bed packages separated by truncation surfaces of varying orientations. They had previously been interpreted as rotational slumps generated on a shelf–slope interface. It is shown that the structures formed in a tidally influenced environment far removed from a slope. They bear strong similarities to structures described from other tidal channel environments and it is proposed that they represent deposition on aggradational margins of such channels. The supposed slope–shelf transition is therefore not present at this level in the Silurian succession and much of the Lough Muck Formation may be of a dominantly shallow-marine origin.

The stratigraphy of the Hawasina Complex is redefined and rationalized to conform with standard stratigraphical nomenclature. Previously proposed tectono-stratigraphical units are abandoned in favour of a system that relies on the lateral correlation of lithofacies between structural units. To this end, the Dibba, Dhera, Wahrah and Al Ayn Formations are incorporated into an expanded Hamrat Duru Group. This group is divided into five formations, the Zulla, Guweyza Sandstone, Guweyza Limestone, Sid'r and Nayid and spans Triassic to Mid Cretaceous (Cenomanian) time. It locally passes up into the syn-orogenic sediments of the Riyamah Member of the Muti Formation. The nomenclature of the deeper-water, chert-dominated formations is left unaltered.

The belemnite genus Pseudohibolites Blüthgen, 1936 was erected without designation of a type species and is invalid according to Article 13b of the International Code of Zoological Nomenclature. The species P. nathorsti Blüthgen and P. caroli Blüthgen are reinterpreted using topotypes from Kong Karls Land and are considered species of Hibolithes Montfort, 1808.

A specimen of the trepostome bryozoan Orbipora from the Lower Arenig of south Wales is described and figured. This is currently the oldest unequivocal bryozoan recorded in the literature. Although mostly decalcified, the colony preserves clear remnants of the large styles which characteristically indent the zooecial apertures in Orbipora. The wide palaeogeographical distribution of Orbipora in the early Ordovician is consistent with the hypothesized planktotrophic larval phase. Theoretical considerations and evidence from the occurrence of Orbipora in south Wales suggest that nearshore clastic environments would be fruitful settings in which to search for further early bryozoans, although quality of preservation may be poorer than in offshore carbonates.