The regionally metamorphosed, Riphean–Cambrian Argyll Group Dalradian rocks of NW Achill Island, western Ireland are disposed in a large-scale, regionally west-facing, tight, recumbent F2 curvilinear fold, with which two ductile shear zones are associated. Clasts in conglomerates within the Dalradian sequence that are deformed by the shear zones preserve evidence for a constrictional overprint of earlier plane strain as the fold became curvilinear, while stretched clasts maintained a constant orientation as the hinge curvilinearity developed. During the constrictional overprint a crenulation fabric, S2b, overprinted a penetrative foliation, S2a, in the shear zones. The S2b has an orientation that varies systematically with that of the fold hinge. It is inferred that, although the S2b surfaces initiated as a dip-slip fabric, there was an increasing degree of strike slip on these surfaces as the fold hinge approached parallelism with the direction of tectonic transport. It is possible that many curvilinear folds have an early history involving plane strain, but that increasing constrictional strain is intrinsic to the later stages of their development.

An alteration zone at the base of a Carboniferous lava flow on the island of Bute resembles modern and ancient weathering profiles, but it is ‘upside down’ in the sense that alteration is most intense at the base and decreases upwards. Values for a Chemical Index of Alteration (CIA) increase from fresh lava and corestones downwards to fine-grained structureless material. The altered material is Mg- and Cu-rich, possibly as a result of migration of these elements from underlying sediments. Rare earth elements (REE) display considerable and systematic mobility and fractionation. In general heavy rare earth elements (HREE) are concentrated during alteration, whereas the light rare earth elements (LREE) are lost. Mobility of the REE appears to be related to atomic weight, with La (the lightest REE) being the most depleted through to Lu, which is the most concentrated REE in the highly altered material. Similar systematic fractionation is shown by some weathering profiles developed on mafic igneous rocks. Movement of water into the volcanic rocks was probably driven by a steep thermal gradient between the hot lava and its sedimentary substrate.

The Palaeogene volcanic succession of the Faroe Islands in the NE Atlantic Ocean is formalised using a purely lithostratigraphic approach and following international guidelines. The Faroe Islands Basalt Group (FIBG) has a gross stratigraphic thickness of ∼6·6 km, dominated by subaerial basalt lava flows, and is subdivided into seven formations. The Lopra Formation forms the basal ∼1·1 km of the Lopra-1/1A borehole, dominated by hyaloclastites, volcaniclastic sandstones and invasive basaltic lavas/sills. It is overlain by the ∼3·25 km-thick Beinisvørð Formation, dominated by laterally extensive basalt sheet lobes separated by minor volcaniclastic lithologies. The Beinisvørð Formation is overlain by the <15 m-thick, inter-eruption, coal-bearing facies of the Prestfjall Formation and the <50 m-thick, syn-eruption, pyroclastic and sedimentary facies of the Hvannhagi Formation. Lava flow volcanic activity resumed with the <1·4 km-thick Malinstindur Formation, dominated by thinly bedded compound basalt lava flows. The top of this formation is marked by a regional disconformity surface, overlain by sandstone and conglomerate deposits of the maximum 30 m-thick Sneis Formation, a newly recognised stratigraphic unit. The final phase of volcanism recorded on the Faroe Islands consists of the >900 m-thick Enni Formation composed of a mixture of basalt sheet lobes and compound flows with abundant volcaniclastic units, e.g. the Argir Beds, that may require a further subdivision at this stratigraphic level. The new lithostratigraphy allows for more refined biostratigraphical and sequence stratigraphic correlations and prepares for a revised geological map of the Faroe Islands.

A revision of the Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic) is presented. The subfamily Odontochilinae Šnajdr is considered a synonym of Dalmanitidae Vogdes. Twenty-one previously and five newly described (three in open nomenclature) species and subspecies occur in the Prague Basin from the lowermost Pragian (one problematic specimen possibly comes from the uppermost Lochkovian) to the Lower Emsian; the last questionable record is from the Upper Emsian. The species have been assigned to four genera and subgenera: Odontochile Hawle & Corda, Reussiana Šnajdr, Zlichovaspis (Zlichovaspis) Přibyl & Vaněk and Zlichovaspis (Devonodontochile) Šnajdr. These trilobites are considered as scavengers or opportunistic predators, living most of their lives as vagrant benthos burying in the muddy substrate to find organic remains. The first undoubted adult-like meraspid specimens are described.

A comparative study of three main igneous rock associations that plot in the K2O–SiO2 diagram shoshonite field: shoshonite series absarokites–shoshonites–banakites (henceforth referred to as shoshonites s.l.), vaugnerites, and potassic lamprophyres, reveals that similarities between the associations are superficial. Vaugnerites and lamprophyres are more magnesian, richer in large ion lithophile and high field strength elements and have higher light rare earth/heavy rare earth ratios than shoshonites. Furthermore, shoshonites have low radiogenic heat production, typical of subduction-related rocks, but most vaugnerites and some lamprophyres are highly radioactive. Relative to bulk-Earth, shoshonites have depleted, asthenospheric mantle-like Sr and Nd isotope signatures, whereas vaugnerites and potassic lamprophyres have enriched, crust or lithospheric mantle-like compositions. Though vaugnerites and some lamprophyres show evidence of crustal contamination, the contaminated magma was not originally shoshonitic. Their composition is consistent with derivation from a metasomatised upper mantle source enriched long before melting, thus precluding an active subduction setting. In conclusion, the term shoshonite, implying late-stage arc magmas, cannot be applied to a rock series simply because it plots into the K2O–SiO2 diagram shoshonite field. Shoshonites with a subduction-related source may, however, be identified by discriminant function analysis.

New three-dimensionally preserved specimens of two euthycarcinoid arthropods, namely Schramixerxes gerem and Sottyxerxes multiplex, allow complete description of both the dorsal and ventral sides of the exoskeleton. The functional morphology is tentatively interpreted for the first time. In S. gerem, the ‘thirteenth somite’, or ‘monosomite’ is fully described and re-interpreted as the main articulatory process of the body, between the cephalic region and the preabdomen. The morphology and arrangement of the two parts of the process clearly indicate that the anterior cephalic region of the body could move laterally and bend ventrally, while posterior somites could only move ventrally. Unlike several other euthycarcinoid species, the ventral side of the head area exhibits one or two plates instead of mandibles; such distinct morphologies are indicative of different feeding mechanisms and behaviours among euthycarcinoid arthropods. Possible homologies with the labrum of Hexapoda support the hypothesis that euthycarcinoids have hexapod affinities.

Microzarkodina is a genus of mainly Middle Ordovician conodonts that has its centre of distribution in Baltoscandia, and much less commonly occurs in southern China, Australia, Argentina and Laurentia. In Baltica a series of species, Microzarkodina russica n. sp., M. flabellum, M. parva, M. bella, M. hagetiana and M. ozarkodella, established themselves successfully. The succession of species ranges from just below the base of the Middle Ordovician (M. russica) to the upper part of the Middle Ordovician (M. ozarkodella). The species are frequently used for biostratigraphical purposes. The largely contemporaneous species Microzarkodina bella and M. hagetiana probably both evolved from M. parva and mostly occurred in separate areas. Microzarkodina ozarkodella probably evolved from M. hagetiana. This present investigation is based on a total of 94,208 elements, collected from 20 sections and one drill-core site in Sweden, one drill-core site and one outcrop in Estonia and two sections in the St Petersburg area in Russia. The Microzarkodina apparatus probably consisted of 15 or 17 elements: four P, two or four M and nine S elements. The S elements include different Sa, Sb1, Sb2, and Sc element types.

A number of approaches to interpreting geochemical data for categorising and correlating metabentonites are presented. Bulk rock geochemistry, combined with data from cognate minerals, provides the most robust means of characterising an altered ash bed. While it is not possible at present to identify one single parameter which can uniquely fingerprint an altered ash bed, it is possible to come close to an unique fingerprint, or ‘Golden Spike’, by utilising an array of geochemical parameters comprising bulk rock element ratios, Rare Earth Elements, Sr and Nd isotopic ratios in apatite, composition of sandine phenocrysts, and the chemical composition of melt inclusions.

A diverse, previously undescribed trilobite fauna from northwest Iran sheds new light on the Early Palaeozoic geography of the Alborz terrane. The structural history of the Alborz region is well known, though faunal data for the area are sparse, especially for the Ordovician. Trilobites, brachiopods, conodonts, bryozoans and echinoderms occur in a red grainstone/packstone near the village of Tatavrud, 35 km southwest of Bandar-e-Anzali. The fossils indicate a Late Ordovician age, although lithologically similar outcrops in northern Iran have previously been considered Silurian. Trilobite genera occurring include Trinodus, Geragnostus, Illaenus, Panderia, Phorocephala, Ovalocephalus, Dicranopeltis, Symphysops, Cyclopyge, and Sphaerexochus. Similar assemblages have been reported from the Late Ordovician of Ireland, Spain, Poland, Norway, northwest China, Kazakhstan and the Turkistan–Alai Ridge (Uzbekistan–Kyrgyzstan border). Reconstructions of Late Ordovician geography place the Alborz terrane near the eastern margin of Gondwana, but there is doubt as to its precise location. Some workers have considered it part of the margin while others have considered it a separate terrane. Several species present, including Mezzaluna tatavrudensis n. sp. and Phorocephala cf. ulugtana (Petrunina, 1975) are very similar to taxa described from the Turkistan–Alai Ridge. In addition, the isocolid genus Paratiresias has only been reported from Iran, the Turkistan–Alai Ridge and northwest China. The presence of these taxa indicates that the Alborz terrane was in close proximity to the eastern margin of Gondwana at this time.

In the recently completed and formally ratified new series and stage classification of the Ordovician System, the base of the Middle Ordovician Series coincides with the base of the global Dapingian Stage. In the Global Stratotype Section and Point (GSSP) of this stage, which is located at Huanghuachang in southern China, the base of the Dapingian Stage is defined as the level of first appearance of the conodont Baltoniodus triangularis. The fact that this species, along with some other taxa present at the Dapingian GSSP, occurs in many sections in Baltoscandia makes it possible to recognise with considerable precision the level of this global stage boundary in Sweden, Estonia, northwestern Russia, and Denmark. In several, but not all, regions, especially in the East Baltic, the global stage boundary coincides with the base of the regional Volkhov Stage and can be tied to the base of the Megistaspis polyphemus Trilobite Zone. The regionally somewhat different relationships between the position of the global stage boundary and a very widespread hardground complex are probably due to the occurrence of local and/or regional unconformities in the upper Floian–lower Dapingian interval. Although biostratigraphically important graptolites are present in the study interval in some Baltoscandic sections, the precise graptolite correlation of the base of the Dapingian Stage remains somewhat unclear, although it appears to be near, or at, the base of the Isograptus victoriae victoriae Zone (Ca 2).

The early Cambrian Chengjiang biota in Yunnan, southern China has yielded many articulated exoskeletons of the spiny redlichiid trilobite Eoredlichia intermedia, of which some have their appendages exceptionally well preserved. Both of the paired uniramous antennae of a medium-sized holaspis consist of 46–50 short segments (articles), each of which bears a fine spine near its inner edge. Behind the antennae there are twenty-one pairs of biramous limbs: three pairs are situated underneath the cephalon, one pair underneath each of the fifteen thoracic segments, and probably three pairs underneath the small pygidium. The endopod consists of a broad basis and seven podomeres, of which the last is divided into three terminal spines. The exopod is blade-like, and according to one interpretation, is dorsally hinged to the basis of the endopod; an alternative suggestion being that both the endopod and exopod are split from the basis, the latter being independent and not forming part of the endopod. The exopod has a prominent anterior rim, and possesses about forty long filaments along the posterior margin, and short setae along the rounded distal lobe. The basic appendage features of the redlichiid trilobites, and likewise the gut, are comparable to those of other known Cambrian polymerid trilobites that belong to more distantly related clades.

Regional scale biotite and cordierite-bearing granites (s.l.) in the Variscan of the Central Iberian Zone (CIZ) are spatially closely associated with cordierite-rich nebulites and cordierite-bearing two-mica granites, and with cordierite-rich high grade hornfelses and cordieritites (>60% cordierite) that are relatively common in the aureoles of these granites. Building on published field evidence, petrological data are presented which, combined with new chemical and isotopic (Sr–Nd) modelling, indicate that the cordierite-bearing granites cannot be derived by simple anatexis of regional sedimentary protoliths; but the data are consistent with a process of reactive assimilation that involves the interaction of biotite granite magma with high-grade host rocks ranging from cordierite nebulites to andalusite-bearing cordieritites. The contribution of the postulated cordierite-rich contaminants to the diversity of cordierite granite compositions is modelled using the compositions of regional Lower Cambrian–Upper Neoproterozoic metasedimentary rocks that are generally chemically mature (CaO very rarely exceeds 1·4%). These rocks include specific horizons in which extreme chemical alteration is attributable to sediment reworking during eustatic falls in sea level. Such compositions may account for the presence of the high concentrations in Al that later produced cordieritites. Fractional crystallisation is also important, particularly in generating the more evolved cordierite granite and cordierite biotite muscovite granite compositions. Although assimilation in situ is normally regarded as a minor contributor volumetrically to evolving plutons, in this instance the emplacement of large volumes of granite magma into a high-T–low-P environment significantly increased the potential for reactive assimilation.

Though little is known of the graptoloid reproductive mechanism, graptolites with putatively sac-like appendages, supposedly ovarian vesicles, have been known from the Moffat Shales Group, Southern Uplands, Scotland, for over 150 years. Locally, these co-occur with isolated, two-dimensional, discoidal or ovato-triangular fossils. In the 1870s, Nicholson interpreted these isolated fossils as being graptoloid ‘egg-sacs’ detached from their parent and existing as free-swimming bodies. He assigned them to his genus Dawsonia, though the name was pre-occupied by a trilobite, and named four species: D. campanulata, D. acuminata, D. rotunda and D. tenuistriata. A reassessment of Nicholson’s type material from the Silurian of Moffatdale, Scotland, and from the Ordovician Lévis Formation of Quebec, Canada, shows that Dawsonia Nicholson comprises the inarticulate brachiopods Acrosaccus? rotundus, Paterula? tenuistriata and Discotreta cf. levisensis, the tail-piece of the crustacean Caryocaris acuminata and the problematic fossil D. campanulata. Though D. campanulata resembles sac-like graptolite appendages, morphometric analysis reveals the similarity to be superficial and the systematic position of this taxon remains uncertain. There is no definite evidence of either D. campanulata or sac-like graptoloid appendages having had a reproductive function.