Proterozoic limestones at several localities in southwestern Spitsbergen contain karst-related features (layered clastic infillings, collapse breccias, deeply weathered depressions) which overprint the Caledonian deformational fabric in the rocks. These features apparently developedbetween middle Devonian and mid-Carboniferous time when the Precambrian basement complex stood high above sea level. Recognition of these karst features may shed light on depositional and tectonic events in post-Caledonian Spitsbergen.

A provenance study was conducted on the Mid-Proterozoic Newland Formation, in which petrographical features of sandstones and geochemical characteristics of shales were integrated to arrive at an internally consistent interpretation.

Sandstones of the Newland Formation are typically arkosic sands and arkoses with very-well-rounded quartz and feldspar grains and only minor amounts of extrabasinal rock fragments. The predominant feldspar types are K-spar and microcline, feldspar grains are smaller than quartz grains, and feldspars show little alteration due to weathering. Detrital modes of Newland sandstones (QFL diagrams) indicate that they were derived from a stable cratonic source. These petrographical features imply a source area dominated by granites and granitoid gneisses, semi-arid to arid climate, tectonic quiescence, and overall peneplain conditions.

Shales of the Newland Formation are dominated by illite, quartz silt, and fine crystalline dolomite. They have small La/Th rations, relatively large Hf contents, and small contents of Cr, Co, and Ni, all indicative of derivation from crust of granitic composition. Small Tio2/Al2O3 ratios also suggest source rocks of granitic composition. The average chemical index of alteration (CIA) for Newland shales is 71.8, which in light of the probable granitoid source indicates modest amounts of chemical weathering. Relatively large SiO2 contents and large K2O/Na2O ratios reflect derivation from stable cratonic areas and tectonic quiescence.

Thus, in general, the petrography of sandstones and geochemistry of shales provides the same provenance clues for the Newland Formation. One notable discrepancy between the two approaches is that the sandstones indicate an arid to semi-arid climate with very minor chemical weathering, whereas the CIA of the shales indicates at least modest amounts of chemical weathering. This indicates on one hand the need to better calibrate the CIA with a large variety of muds from modern climatic settings, and on the other hand the possibility that this discrepancy is due to transport segregation.

Use of the nautiloid cephalopod generic names Orthoceras and Michelinoceras is briefly reviewed. Two new genera, Imbricatoceras (upper Ordovician-Silurian) and Radnoroceras (Wenlock-Ludlow), are proposed for common taxa with distinctive ornamentation.

Geochemical data on the Dhanjori volcanics of the Singhbhum craton indicate that they range from basalt to andesite and show an iron-enrichment trend. Various chemical characteristics suggest that they are differentiated along the trend similar to that of orogenic suites and have a strong affinity with island arc tholeiites. The field relationships as well as other geological information also support this conclusion and indicate their eruption on a thin continental margin. It is inferred that the Dhanjori volcanics were probably erupted as a result of plate convergence in northern Singhbhum with subduction of oceanic crust below the Singhbhum craton.

New evidence, provided by bracketing marine molluscan faunas, suggests a Late Albian age for fossil forests in the upper part of the Fossil Bluff Group of Alexander Island. These in situ forests are underlain by Late Aptian and Late Albian strata containing faunas including ammonites (the last of which is Lechites), inoceramid bivalves, dimitobelid belemnites and trace fossils. The tree-bearing levels occupied a fluvial dominated environment, subject to periodic major floods. They were transgressed during late Albian time by returning marine conditions with diverse faunas, including hamitid and puzosiid ammonites. The increased precision in dating of the fossil forests will improve palaeobotanical contributions to climate and environmental studies.

The age of formation of the Büyük Menderes graben (middle Burdigalian-middle Serravallian) is earlier than previously considered (Tortonian). This supports the contention of Seyitogˇlu & Scott that north-south extensional tectonics in west Turkey commenced at the latest during early Miocene time, following a Palaeogene compression.

The lithostratigraphic and biostratigraphic subdivisions of the Cambrian sequence in the Holy Cross Mountains of Poland are briefly presented and discussed. In accordance with recent progress in Cambrian stratigraphy and correlation in Great Britain and Scandinavia, a new proposal for chronostratigraphic stages is made. It is suggested that these stages are suitable for the Cambrian areas of central and northwest Europe, comprising Great Britain, Scandinavia and Poland. The formal establishment of the stages, a task for the Commission on Cambrian Stratigraphy, could be made using British or Scandinavian stratotypes.

A pilot study has demonstrated that heavy mineral analysis is a useful guide to the provenance of Silurian turbidites in the Southern Welsh Basin. The results confirm the sedimentological evidence for two distinct source areas of coarse clastic detritus, one lying to the south and the other to the east. They also provide mineralogical criteria by which the two source areas may be distinguished. The southern area provided material with relatively low mineral diversity, and is characteristic in having low rutile/zircon ratios, whereas the eastern source provided more diverse assemblages, generally with high rutile/zircon ratios. The southern source shows variations in terms of apatite/tourmaline ratio, with the older Aberystwyth Grits Group tending to contain relatively low apatite compared with the younger Cwmystwyth Grits Group (Rhuddnant and Pysgotwr Grits formations). There is evidence for polycyclic material and volcanic detritus in both southerly and easterly derived samples; however, easterly-sourced sandstones apparently tapped a more lithologically-diverse terrain.

Monograptus chrysalis sp. nov. from the magnus Zone (Aeronian) of central Wales shows a previously unrecognized combination of thecal types. Distally, the thecae possess marked lappets and short lateral horns, and approximate to those of the revolutus group of monograptids and some described examples of Pribylograptus. Proximally, the thecae are elongate and slender, and possess slit-like apertures below a distinct geniculum. They resemble the proximal thecae of Monograptus imago sp. nov., one of the earliest recognized British monoclimacid monograptids, from the succeeding leptotheca Zone of central Wales and the Lake District. It is suggested that M. chrysalis arose from a graptolite of the revolutus group by retraction or suppression of the hooked proximal thecae, while the distal thecae remained constant, and that M. imago then evolved from M. chrysalis by a spreading of the proximal end characteristics distally. The proximal morphology and overall record of the monoclimacids, though, suggests that they may be polyphyletic; in this paper, the generic name Monoclimacis is reserved for the late Telychian graptolites of the vomerina group.

Recent studies indicate that the Rum Tertiary ultrabasic intrusion formed in situ, and was not emplaced as a fault-bounded plug. The suggestion that the Main Ring Fault was the primary pathway for the flow of meteoric-hydrothermal fluids on Rum is therefore seriously flawed. Oxygen isotope evidence is presented indicating that the contact zone of the intrusion was the major pathway for meteoric fluids during cooling of the pluton. δ18O depletions of over 12‰ correlate with hydrothermal alteration assemblages, indicating that the bulk of the interaction with meteoric fluids took place at low temperatures (200–450 °C).

Oolitic ironstones are described from the early Cretaceous non-marine Wealden sediments of southeast England. The recognition of non-marine oolitic ironstones in the geological record is rare and, therefore, warrants further study. The oolitic ironstones described take two forms, named here type-I and type-2 ironstones.

Type-1 ironstones contain pisoids and ooids of berthierine together with sandstone fragments and detrital quartz grains. The pisoids (up to 0.5 cm in size) vary from subspherical to highly irregular. The smaller ooids (up to 1 mm in size) are generally ellipsoidal but strongly asymmetrical forms are also present. The form of these pisoids and ooids suggest that mechanical accretion was not the dominant mechanism controlling their formation. It is proposed that this ironstone type formed from the reworking and redeposition of local soil material.

Type-2 ironstones, of which only one unequivocal example has been studied, is composed of iron oxide ooids set in a detrital matrix. The ooids are most commonly regularly ellipsoidal and exhibit a decrease in iron at their centres. It is proposed here that the ooids suffered post-depositional iron depletion at their centres, in a similar fashion to that proposed for the recent Lake Chad oolites. There is no unequivocal evidence as to the origin of the ooids.

This study is important in that it shows that different ironstones can be formed by different processes essentially within the same environment. Comparison of non-marine oolitic ironstones with the better-developed marine examples should prove a valuable exercise.

Major, trace and REE geochemistry, together with Nd isotope determinations, provide new insights into the provenance of seven pebbles of igneous origin from an early Silurian facies of the Caban Conglomerate Formation from central Wales. The geochemical composition of the pebbles supports formation in a subduction related environment on an active continental margin. Biotite whole-rock Rb-Sr systematics constrain the age of a granite pebble to 650±38 Ma. The pebbles provide discrete examples of Avalonian basement which contributed to the isotope composition of sedimentary rocks in the Welsh Basin and one granite pebble provides a rare example from the Welsh Basin of an igneous rock with a Palaeoproterozoic depleted mantle model age.

The Bedded Series of the Mona Complex at Rhoscolyn comprises two groups of clastic metasediments: the Holy Island Group, consistingof quartzites, impure psammites and pelites, with well-preserved bedding, is overlain conformably by the New Harbour Group, which is for the most parthomogeneously semi-pelitic without surviving bedding. Both groups have undergone the same two major tectono-metamorphic episodes, but with differing response. In the Holy Island Group the first episode (Dx) produced nearly upright and upward-facing folds (Fx) with an axial planar foliation (Sx), which varies from an anastomosing or rough-spaced cleavage in quartzites to a penetrative phyllitic schistosity in pelites. In the New Harbour Group Dx has generally obliterated original bedding surfaces, replacing them with a composite foliation (Sx) of fine compositional banding and a penetrative schistosity, together with a stretching lineation (Lx), the latter being at a high angle to the Fx axial direction. The Dx structures are attributed to a major episode of compressional tectonics.

The structures attributed to the second deformation (Dy) includestrata-bound sets of quartz-filled tension fractures (attributed by most previous authors to an earlier episode), abundant NNW-verging asymmetric folds (Fy) of Sx, and a sporadically developed set of shear fractures which constitute a crenulation cleavage (Sy) axial planar to the folds. It is suggested that all these structures were produced by a single agency. One interpretation is that the observed shear fractures and folded tension fractures correspond fairly closely to and provide a natural analogy of those obtained in the classical simple shear experimentsof Riedel. In this case all the Dy structures can be accounted for by the action of a large-scale simple shear couple (Cy), whose vergence and shallow dip were both towards the NNW. Such a mechanism may imply a gravity-dominated regime of net horizontal extension in a NNW-SSE direction, with extension being less constrained to the north than to the south. J. W. Cosgrove has suggested an alternative interpretation, that all the Dy structures can be explained as reverse kink bands; the simple shear interpretation is here preferred because the angle between Sy and the estimated direction of Pmax during Dy was < 45°; the kink band model would require an angle > 45°.

The fact that cleavage vergence boundaries for both Sx and Sy occur close to the hinge zone of the Rhoscolyn Antiform is consistent with either Dx or Dy age for the initiation of this fold. However, when fold limb length (or limb rotation) vergence is considered, the presence of an Fx0 vergence boundary but absence of an Fxy vergence boundary (and by implication of an Fy0 boundary) is consistent with a Dx age but difficult to reconcile with a Dy age.

A new species of archaeocyath sponge, Dictyocyathus neptunensis, is described from the lower third of the Nelson Limestone of the Neptune Range, Antarctica. Based on the presence of the trilobites Nelsonia schesis and Amphoton oatesi, these strata are interpreted to be mid- to late middle Cambrian in age. D. neptunensis shows a branching, low integration modular form and a very simple skeletal type. Such an organization is predicted from known morphological trends within the early Cambrian Archaeocyatha. Specimens are not in life position, and probably form part of a storm deposit. The absence of Dictyocyathus from latest early Cambrian (Toyonian) strata worldwide suggests a convergent nature for this highly simplified skeletal type in archaeocyaths.

Ichthyosaur remains found in late Triassic shallow marine limestones in Quebrada Doña Inés Chica (latitude 26° 07′ S; longitude 69° 20′ W), northern Chile, are the oldest known ichthyosaur fossils from Central and South America. The previous oldest South American ichthyosaur was recorded in Hettangian rocks, also from northern Chile. The fossils comprise five worn teeth, one paddle bone and one scapula or humerus fragment, all collected from a single bed at the same locality. Although the material has not been identified to a generic or specific level, its presence alone broadens the knowledge of the distribution and habitat of Triassic ichthyosaurs. Late Triassic ammonites and brachiopods in the same stratum provide the age control.

The Ludlow Bone Bed in the Upper Silurian of the Welsh Borderland shows an anomalously high concentration of iridium (0.49 ppb) compared with background (0.040 ppb Ir). Considering the overall major and trace element pattern and the mineralogy of the bone bed, it appears that the bulk of their has precipitated from sea water and is not primarily related to an asteroid impact event. A secondary relation of the Ir to such an event, however, cannot be excluded. The profound sedimentological similarity (skeletal sands and hummocky cross-stratification) between the Ir-carrying ‘storm deposit’ at the Cretaceous–Tertiary boundary at Brazos River, Texas, and the LBB and overlying sediments may indicate such a relation.

The two most commonly used biostratigraphic standards for the Campanian–Maastrichtian boundary are the appearance of the belemnite Belemnella lanceolata (Schlotheim) and the disappearance of the planktic foraminiferan Globotruncanita calcarata (Cushman). The first is a boreal standard, the second tethyan. The assumption that the two coincide is false. In Mississippi the disappearance of G. calcarata is the same eustatic peak of sea-level which in north Germany lies near the top of the Nostoceras polyplocum Zone, within boreal nannofossil Zone CC/B22. This places the foraminiferal standard somewhere between 1.3 and 3.5 m.y. older than the belemnite standard. The belemnite standard is at or close to the appearance of Gansserina gansseri (Bolli) in Mississippi.

Preliminary results are reported of geochemical and mineralogical studies on the Nod Glas sediments of Caradoc age (clingani-linearis biozones) in Wales. Results are based on sampling at three localities in North Wales, together with a coeval section in South Wales. Data have been obtained for 21 elements by ICPAES, and for organic C, S and ignition loss. XRD analysis has provided semi-quantitative data on abundances of muscovite 2M1, quartz, albite and chlorite. Mean values of K2O, organic C, S, Cu, Zr and Ba are higher in the Nod Glas than in adjacent strata, while Fe203, MnO, MgO, CaO and P205 are lower. Analogy with the chemical composition of modern sediments reinforces the interpretation of the Nod Glas as being deposited under dysaerobic to anaerobic bottom conditions. There is considerable variation in composition between different Nod Glas sections. Analysis of mineral/chemical relationships shows some consistencies: for example, chlorite shows significant positive correlations with the heavier transition elements Mn to Zn, as well as with Li and Mg, presumably due to enrichment by adsorption of these elements onto subsequently recrystallized smectites. Other relationships are less consistent: organic C is correlated with muscovite (where it is probably held in interlayer sites as a relic from a smectite precursor) and sometimes also with albite. Inconsistencies between the sections in mineral/element interrelations may be due to diagenetic/metamorphic changes.