Tectonic joints localized within deformation band shear zones on the Kaibab uplift in Utah, USA, show the same spacing and distribution characteristics as joints controlled by primary lithological mechanical stratigraphy, despite the fact that deformation band shear zones are secondary structural features oblique to primary sedimentary layers. The spacing and distribution of joints that traverse deformation band shear zones are important factors in the permeability and connectivity of sandstone reservoirs compartmentalized by deformation band shear zones.

Major and trace element data on Tertiary continental basalt flows from the Shalatein area, Red Sea coastal plain of Egypt, have been presented and used to obtain more information about their source region and the processes involved in their generation. The rocks are mainly alkali olivine basalt with MgO and Mg no. in the range of 9.8–5 wt % and 65–46, respectively. They display wide variations in incompatible element concentrations, particularly LREE, Zr, Nb, K, Y, Ba and Sr. There is no evidence of significant crustal contamination or a lithospheric mantle signature in these rocks. Normalized trace element patterns and diagnostic elemental ratios are very similar to those of modern ocean-island basalts (OIB) a feature which suggests that the mantle source region was the asthenosphere. Comparison with the different types of OIB indicates that the basalts may be derived from a high U/Pb (HIMU) source with slightly elevated K and Ba contents. The basalts show general trends of increasing incompatible elements (K2O, Nb, Y, Sr and Yb), and decreasing contents of compatible elements (Cr, Ni, Sc and Ca) with decreasing Mg no. Furthermore, TiO2, P2O5, LREE and Th define maxima at about Mg no.=56, suggesting late fractionation of Fe–Ti oxides and apatite. Although these variations are consistent with fractional crystallization processes, the wide variations in LREE contents and the incompatible trace element ratios Ce/Y (1.2–3.8), Zr/Nb (2.3–7.1) and Nb/Y (0.6–4) in the least fractionated samples (Mg no. > 56) suggest that fractional crystallization involving the observed phenocryst assemblage (olivine and clinopyroxene) cannot fully explain such compositional variations. Modelling of the mafic rocks (Mg no. > 56) using REE suggests varying degrees of partial melting of an enriched mantle source region in the garnet stability field. Partial melting is attributed to plume-related mantle upwelling beneath the Red Sea rift system.

Heavy minerals in Ordovician successions in western Ireland record, in the Upper Arenig Sheeffry Formation, the erosion of an ophiolite/island arc complex. The appearance of staurolite and garnet at a basin-wide horizon in the Lower Llanvirn Upper Derrylea Formation signals the unroofing of the Dalradian metamorphic complex. Parts of the Ordovician sequence on Inishturk and in two small inliers are correlated with the standard sequence with unexpected results. The garnet-, sillimanite-, and staurolite-bearing Letter Formation correlates with the Upper Derrylea Formation and, on Inishturk, heavy minerals in south-younging turbidites reveal a sinistral ramp zone, that places the Sheeffry Formation structurally above and to the south of the younger Derrylea Formation.

The Volkhov Regional Stage (Middle Ordovician) in the East Baltic preserves diverse fossil assemblages dominated by epibenthic suspension feeders. Brachiopods, ostracodes, conodonts, echinoderms and bryozoans are the main components of palaeocommunities obtained from clay horizons in the Putilovo section (St Petersburg region, Russia), whereas trilobites, machaeridians, hyolithids, graptolites, benthic foraminifers and gastropods are rare or occur sporadically. Brachiopod bioclasts volumetrically dominate the debris of the studied sediments. Quantitative faunal data are used to assess species diversity patterns, as expressed by the species richness (total number of species in the standardized sample size) and by the evenness or equitability of the community. The numerical abundance of particular taxa in each standardized sample was used to evaluate the density of the fauna. The communities in the Volkhov Stage in Putilovo Quarry reveal a remarkable stability throughout the studied interval and are characterized by high density (1000–6000 specimens per 100 g), relatively moderate species richness (10–15 species) and a moderately variable equitability (0.3–0.7) for the dominant fossil groups (conodonts, ostracodes and brachiopods). Ostracodes significantly increase in numbers within the upper part of the section. This confirms a shallowing of the basin during the late Volkhov interval. Small-scale variability of the diversity estimates does not correlate with the small-scale sea-level changes reconstructed for this part of the basin. It may be connected with error in diversity measurement, or the result of undetected environmental parameters. Variability estimates for different faunal groups are poorly correlated because particular groups have different environmental tolerances.

Synmagmatic and solid-state structures within the Naxos pluton and its rim may provide insight into the interplay between plutonism and regional deformation at upper-crustal level. Within the hornblende–biotite granite of western Naxos, synmagmatic foliations display two distinct patterns, onion-skin in the north and tangential to the rim in the south. The two areas are separated by the NE-trending Glinadon fault. Deformed mafic enclaves in the pluton are prolate, with their long axes parallel to the synmagmatic lineation. In contrast, phenocryst distribution analysis, using the Fry method, defines an apparent oblate strain with a horizontal stretching lineation. Planar markers within the pluton progressively steepen through the vertical at the east pluton border. Several lines of evidence, such as dykes intruding axial areas of rim-parallel folds, foliated or folded aplite veins, folds and spaced cleavage in the mollase, and inverted stratigraphy, suggest pluton emplacement and deformation during transpressional deformation. A northward divergent flow regime with magma spreading out mainly from the Naxos fault, and the deflection of both the synmagmatic foliation pattern and the flow lines at the Glinadon fault, suggest that the NE–SW- and N–S-trending faults were active during pluton formation. In the south the pluton has grown by the expansion of dykes occupying P-shear positions with respect with the Naxos fault; in the north a piecemeal block down-drop complements this process and favours voluminous magma concentration. During the late evolutionary stages of pluton construction, the magma chamber was compartmentalized into NE-trending sectors affected by block rotation in an anticlockwise manner. Understanding the role of faults in the emplacement of the Naxos pluton is important for understanding emplacement of other plutons in the Aegean Sea region, since most of them are controlled by N–S- (Ikaria pluton) or NE- (Tinos, Serifos and Delos plutons) trending faults.

Abundant arthropod trackways, assigned to Diplichnites gouldi, are described from the Lower Old Red Sandstone (Early Devonian; Lochkovian) of Pant-y-Maes quarry, Brecon Beacons, South Wales. The trackways are preserved on bedding planes of finely laminated planar and rippled siltstones. The sedimentology of the succession indicates that these units represent bar top and marginal deposits in a braided fluvial setting. Two trackway types are recognized (Type A and B); comparisons with contemporaneous myriapodous producers favour kampecarid and eoarthropleurid myriapods, respectively. Functional analysis of the trackways indicates that the producers were not using the most efficient, stable, walking techniques, but instead utilized in-phase ‘swimming stroke’-like gaits. Together with their occurrence on rippled surfaces, and lateral displacement of some trackways (attributed to currents), this indicates that they were produced sub-aqueously.

The relationship between the Dalradian Supergroup and the Highland Border Complex in Scotland has remained contentious for over a century. In western Ireland, the contact between the Dalradian Supergroup and the Clew Bay Complex (a correlative of the Highland Border Complex) is superbly exposed on the island of Achill Beg on the North Mayo coast. The unfossiliferous South Achill Beg succession has been traditionally assigned to the Clew Bay Complex, and this interpretation is supported by a combination of Sm–Nd model age data, heavy mineral analysis and lithostratigraphic correlation. TDM ages range from 1.99–2.66 Ga (mean=2.28 Ga, n=6). Detailed structural mapping shows that both the Dalradian and the Clew Bay Complex share the same structural history. A D1 high strain event is common to both units, and is associated with the development of tectonic slides. The D2 event is responsible for the formation of crustal-scale nappes. In both units, beds are consistently downward facing on the S2 foliation. Later dextral shearing (D3) resulted in the tilting of the originally recumbent, S-facing D2 nappes into this downward-facing orientation. Rb–Sr and 40Ar–39Ar radiometric dating of muscovite confirms that both units were deformed contemporaneously as the S2 nappe fabric in each is dated at c. 460 Ma. This Middle Ordovician age for deformation of the Clew Bay Complex is highly significant, not least because published microfossil data suggest a Silurian age.

Many late Mesozoic lamprophyre dykes occur in the Taihang Mountains (north China). These lamprophyres are rich in large ion lithophile elements (e.g. Rb, Sr, Ba and K) and light REE, and have highly differentiated REE patterns. They show large but regular variations in chemical and Nd–Sr isotopic compositions. All these suggest that the lamprophyres were produced from differentiation of a parental magma, coupled with contamination by lower crust. The parental magma was derived from melting of a long-term enriched sub-continental lithospheric mantle source as is indicated by the highly enriched isotopic signatures of the lamprophyres. Mantle enrichment in the area was probably produced by interaction of volatile-rich melts released from the asthenosphere with the above lithosphere in middle Proterozoic times.