Protector Shoal, the northernmost and most silicic volcano of the South Sandwich arc, erupted dacite–rhyolite pumice in 1962. We report geochemical data for a new suite of samples dredged from the volcano. Geochemically, the dredge and 1962 samples form four distinct magma groups that cannot have been related to each other, and are unlikely to have been related to a single basaltic parent, by fractional crystallization. Instead, the silicic rocks are more likely to have been generated by partial melting of basaltic lower crust within the arc. Trace element and Sr–Nd isotope data indicate that the silicic volcanics have compositions that are more similar to the volcanic arc than the oceanic basement formed at a back-arc spreading centre, and volcanic arc basalts are considered to be the likely source for the silicic magmas. The South Sandwich Islands are one of several intra-oceanic arcs (Tonga–Kermadec, Izu–Bonin) that have: (1) significant amounts of compositionally bimodal mafic–silicic volcanic products and (2) 6.0–6.5 km s−1P-wave velocity layers in their mid-crusts that have been imaged by wide-angle seismic surveys and interpreted as intermediate-silicic plutons. Geochemical and volume considerations indicate that both the silicic volcanics and plutonic layers were generated by partial melting of basaltic arc crust, representing an early stage in the fractionation of oceanic basalt to form continental crust.

A description is given of a nearly complete specimen of a new Ordovician eurypterid genus belonging to the family Stylonuridae. The classification of the Eurypterida is discussed; two super-families and two new families are proposed and three new names substituted for pre-occupied generic names.

Detailed dinoflagellate cyst analysis of the Lower–Middle Miocene Berchem Formation at the southernmost margin of the North Sea Basin (northern Belgium) allowed a precise biostratigraphical positioning and a reconstruction of the depositional history. The two lower members of the formation (Edegem Sands and decalcified Kiel Sands) are biostratigraphically regarded as one unit since no significant break within the dinocyst assemblages is observed. The base of this late (or latest) Aquitanian–Burdigalian unit coincides with sequence boundary Aq3/Bur1 as defined by Hardenbol and others, in work published in 1998. A hiatus at the Lower–Middle Miocene transition separates the upper member (the Antwerpen Sands) from the underlying member. The greater part of the Antwerpen Sands were deposited in a Langhian (latest Burdigalian?)–middle Serravallian interval. The base of this unit coincides with sequence boundary Bur5/Lan1. Biostratigraphical correlation points to a diachronous post-depositional decalcification within the formation since parts of the decalcified Kiel Sands can be correlated with parts of the calcareous fossil-bearing section, up to now interpreted as Antwerpen Sands. The dinoflagellate cyst assemblages are dominated by species with a inner neritic preference, although higher numbers of oceanic taxa in the upper part of the formation indicate incursions of oceanic watermasses into the confined depositional environment of the southern North Sea Basin.

Abundant sulphur is present in the Late Miocene evaporitic sequence of the lacustrine Hellín basin in SE Spain. Weathering of Triassic evaporites controlled the chemical composition of the Miocene lake. The lacustrine deposits comprise gypsum, marlstones, diatomites and carbonate beds. Sulphur-bearing carbonate deposits predominantly consist of early diagenetic dolomite. Abundant dolomite crystals with a spheroidal habit are in accordance with an early formation and point to a microbial origin. The carbon isotopic composition of the dolomite (δ13C values between −10 and −4‰) indicates mixing of lake water carbonate and carbonate derived from the remineralization of organic matter by heterotrophic bacteria. Dolomite precipitated syngenetically under evaporitic conditions as indicated by high oxygen isotope values (δ18O between +6 and +11‰). Nodules of native sulphur are found in gypsum, carbonate beds and marlstone layers. Sulphur formed in the course of microbial sulphate reduction, as reflected by its strong depletion in 34S (δ34S values as low as −17‰). Near to the surface many of the sulphur nodules were in part or completely substituted by secondary gypsum, which still reflects the sulphur isotopic composition of native sulphur (−18 to −10‰). This study exemplifies the role of bacterial sulphate reduction in the formation of dolomite and native sulphur in a semi-enclosed lacustrine basin during Late Miocene time.

A suite of Tertiary alkaline porphyritic microgranites and hybrid and peralkaline granite from northwest Pakistan is described, with six rock analyses (five of them new). The microgranites, an earlier group of which some contain garnet, have undergone metamorphism, lacking in the granites. The microgranites are shown to be precisely similar to those from the Shewa–Shahbazgarhi area, for which four analyses (two of them new) are presented, and related to a third group from Tarbela. The mineralogy of the rocks is discussed, with seven new analyses of aegirine, riebeckite, ferrohastingsite and astrophyllite, and X-ray determinations of the feldspar compositions. The granites are considered to be related to the undersaturated syenites and associated rocks of Koga, and a petrogenetic scheme for the alkaline province is presented, with a K/Ar age determination, tentatively deriving the source magma (quartz trachytic) from a Himalayan tholeiite.

The discovery of marine fossils in the Upper Palaeozoic of the Oslo Region suggests a previously unknown marine transgression of probable middle Carboniferous age. The fossiliferous sequence in the Oslo district was probably deposited in a very shallow marine environment as indicated by its fauna, ooids and the strong micritization of the fossils. The discovery of this sequence is consistent with the rift model for the Oslo Rift Zone, and suggests a connection with the Variscan Ocean.

Borehole evidence from the Isle of Rügen, and geophysical data from the adjacent Baltic Sea suggest a Caledonian deformation front that caused NNE-directed thrusting on the East European Platform. It is thought to mark a Caledonian suture zone which was reactivated in syn- to post-Variscan events to form the Rømiø-Møn Fault Zone.

The position of a coastline in time and space is determined by (1) the vertical displacement and/or tilting of the depositional surface, (2) the rate of sediment accumulation or erosion across that surface, and (3) variation of sea-level. All three rates of change may vary through time. We present computer simulations of coastline movements that illustrate the interaction of the above variables, with (1) and (2) held at various defined levels whilst (3) is varied according to the late Quaternary glacio-eustatic sea-level curve. The Corinth Canal section in central Greece exposes uplifted late Quaternary coastal transgressive cycles, each of which may be related to a radiometrically dated, c. 100 ka duration, cycle of sea-level change. Observed stratigraphic sequence geometries are predicted by forward modelling based on the known glacio-eustatic history over the last 430 ka. Milankovitch orbital parameters are calculated for the Carboniferous period. The obliquity and precession parameters are found to have been significantly shorter than at present. A simulation is presented of the effects of sea-level changes across low gradient, fluvio-deltaic environments such as existed in northern England and other parts of the Laurentian continental margin during Upper Carboniferous time.

The Bossòst dome is an E–W-trending elongated structural and metamorphic dome developed in Cambro-Ordovician metasedimentary rocks in the Variscan Axial Zone of the central Pyrenees. A steep fault separates a northern half-dome, cored by massif granite, from an E–W-trending doubly plunging antiform with granitic sills and dykes in the core to the south. The main foliation is a flat-lying S1/2 schistosity that grades into a steeper-dipping slaty cleavage at the dome margins. Three major deformational and two metamorphic phases can be differentiated. S1/2 schistosity is an axial planar cleavage to W-vergent recumbent folding that probably occurred in mid-Westphalian time. Peak regional metamorphism M1 is characterized by static growth of staurolite and garnet following thermal relaxation of the previously thickened crust. Strong non-coaxial deformation recording uniform top-to-the-SE extension during D2a is preserved in staurolite–garnet schists in a 1.5 km thick, shallowly SE-dipping zone in the southeastern dome. A 500 m thick contact aureole (M2) was imprinted on the regionally metamorphosed rocks following the intrusion the Bossòst granite during D2b. More coaxial deformation prevailed during synkinematic growth of M2 phases in the inner part of the contact aureole around the northern part of the dome, where it obliterated D2a fabrics. Progressive non-coaxial deformation continued in the southeastern antiform and is recorded by late-synkinematic growth of cordierite. Successive overprinting of the M1 staurolite–garnet assemblage by andalusite and cordierite of M2 is preserved in the southern part. The assemblage muscovite+cordierite+staurolite+biotite is considered metastable, given the low Mn and Zn contents of staurolite and cordierite, and interpreted as the result of prograde metamorphism during decompression. P–T conditions during M2 were approximately 3 kbar and 600 °C. Pervasive crenulations and mesoscopic to regional southerly verging folds are the result of D3 NNE–SSW compression post-dating ductile deformation and contact metamorphism. Polymetamorphic assemblages of the Bossòst dome preserve a regionally confined zone of ESE-directed extensional shearing within an overall N–S compressional setting. Exact timing of extensional shearing is not known, but can be constrained by recumbent folding during the mid-Westphalian and granitic intrusions, which confine it to Late Carboniferous time (c. 305 Ma). Crustal-scale flat-lying extensional shear zones with similar orientation and time frame are observed in the Hospitalêt massif of the eastern Axial Zone. This suggests that crustal extension, though probably restricted by regional strain partitioning over orthogneiss or intruding granitic bodies within an overall compressive setting, was not uncommon in Late Carboniferous time in the Axial Zone of the Pyrenees.

1. Succession of Silurian Rocks in the South of Scotland.—The oldest fossiliferous strata yet detected in the Silurian district of the South of Scotland are the dark Graptolitic shales forming the well-known Moffat Series. The total thickness of this group is under 600 feet, but it is nevertheless capable of separation into three very distinct palæontological divisions, each characterized by a large proportion of peculiar fossils. The first of these divisions is of Llandeilo age, the second represents a portion of the Bala formation of North Wales, and the third, or Birkhill division, appertains, at least in part, to the epoch of the Lower Llandovery.

Erosion of headlands along the southern coast of Victoria results chiefly from the attack of storm waves, and is concentrated above a defined level, marked by certain level shore platforms, whose surfaces are at about high tide level. These platforms are initiated and maintained by storm wave erosion. Their surfaces undergo planation and lowering, chiefly by the scouring action of waves of translation, but increasingly by water-layer weathering as the platforms age and widen.

The Troodos Massif of Cyprus exposes a classic and much-studied ophiolite sequence representing oceanic crust of Late Cretaceous age. K-Ar dating of the sheeted dykes and of the overlying pillow lavas gives a range of 83±3 Ma (earliest Campanian) and 75±5 Ma (late Campanian) respectively for the formation of the upper levels of the ophiolite. An autochthonous sequence of Late Cretaceous to Recent age sediments is exposed resting on the ophiolite, the oldest part of which reflects sedimentation in an apparently deep marine, oceanic setting. Little biostratigraphical information is available to constrain the chronostratigraphy of these sediments in relation to the complex geological history of the island, including the uplift and unroofing of the ophiolite, despite their richness in microfauna and flora. This paper provides an integrated biostratigraphical study based on radiolaria, planktonic foraminifera and calcareous nannofossils of the oldest part of the supra-ophiolite succession, of the Cretaceous Perapedhi, Kannaviou, Moni and Kathikas formations. For the first time, well-defined micropalaeontological evidence establishes the relative ages of these formations. The umbers of the Perapedhi formation are no younger than Campanian in age while the volcaniclastic sediments of the Kannaviou formation were also deposited during Campanian times. The matrix of the Moni formation contains a microfauna consistent with the hypothesis that it is derived from the Kannaviou. In contrast, the Kathikas formation is composed of sediment derived mainly from the allochthonous Mamonia complex, but autochthonous pelagic interbed horizons demonstrate that it was deposited probably within a very short time interval during the late Maastrichtian. Key index species are figured, including the first published micrographs of Cretaceous planktonic foraminifera from Cyprus.

The late Precambrian and Cambrian world experienced explosive evolution of the biosphere, including the development of biomineral skeletons, and notably of phosphate and siliceous skeletons in the initial stages of the adaptive radiation. Ongoing research indicates profound changes in climate and atmospheric carbon dioxide over this span of time. Glacial conditions of the Varangian epoch occur enigmatically at low latitudes, associated with carbonate rocks. Later changes in palaeogeography, sea level rise and salinity stratification encouraged prolonged ‘greenhouse’ conditions in both latest Precambrian and Cambrian times, with indications of relatively low primary production in the oceans. The Precambrian–Cambrian boundary interval punctuated this trend with evaporites, phosphogenic events and carbon isotope excursions; these suggest widespread eutrophication and conjectured removal of carbon dioxide from the atmosphere. Whatever the cause, nutrient–enriched conditions appear to have coincided with the development of phosphatic and siliceous skeletons among the earliest biomineralized invertebrates.

The SW–NE-striking Porongos belt, located between juvenile Neoproterozoic rocks in the west and the Dom Feliciano belt, characterized by intense reworking of older crust, in the east, comprises a greenschist to amphibolite-facies metavolcano-metasedimentary succession (Porongos sequence) of unknown age with some exposures of Palaeoproterozoic gneisses (Encantadas gneisses). High-temperature ductile deformation of the basement gneisses comprises at least two magmatic events followed by three deformational phases including folding and shearing (DT1–DT3) and can be attributed to the Palaeoproterozoic Trans-Amazonian orogeny. The deformation of the Porongos sequence occurred during the Neoproterozoic Brasiliano orogeny and comprises four ductile deformation phases (DB1–DB4), including two phases of isoclinal folding associated with shearing recorded in mylonitic layers, followed by closed NW-vergent folding and thrusting leading to formation of a thrust stack. Uplift of the basement and formation of late tectonic sedimentary basins occurred as a result of semi-ductile to brittle block faulting in a sinistral strike-slip regime. The Porongos sequence can be subdivided into a southeastern and a northwestern part. Trace element analyses as well as Sm–Nd and Rb–Sr geochemical data indicate partial melting and significant contamination by old continental crust for the metavolcanic rocks. The metavolcanic rocks show εNd(t=780 Ma) values of −20.64 and −21.72 (northwestern units) and −6.87 (southeastern sequence). The metasedimentary rocks were derived from late Palaeoproterozoic to Archaean sources, and the data indicate different sources for the northwestern and southeastern rock units of the Porongos sequence. εNd(t=780 Ma) are −6.25 and −6.85 in the southeastern units, with TDM model ages between 1734 and 1954 Ma, and vary between −14.72 and −17.96 in the northwestern parts, which have TDM model ages between 2346 and 2710 Ma. High 87Sr/86Sr(t) values between 0.7064 and 0.7286 confirm reworking of older crust. Isotopic signatures of the Porongos sequence do not show indications for a significant contribution from a Neoproterozoic juvenile source. A passive margin or continental rift environment is suggested for the tectonic setting of the Porongos belt, which is compatible with both deposition of shallow marine to deep marine sediments and stretching of continental crust leading to volcanism which is characterized by significant contamination by old continental crust.

A 425 ka long record from piston core GIK17925-3 taken in the northeastern South China Sea was used to study the environmental conditions controlling the distribution of the Zoophycos trace fossil. The 12 m long core offers a unique opportunity to study the response of the Zoophycos-producing animal to environmental variations over four glacial–interglacial cycles. The trace fossils show a strong glacial to interglacial variation in their abundance with a special preference for intervals with low sedimentation rates. Additional X-ray radiograph studies of piston cores from the Southeast Asian Marginal Seas show that the trace fossil Zoophycos is widespread in slope and deep-marine sediments, with the highest abundances encountered in low sedimentation rate settings. The preference of the Zoophycos producer for low sedimentation rates in a setting with strong seasonal fluctuations in food supply due to the shift between winter and summer monsoons, is interpreted to be the result of a cache-model behaviour, where food is collected during rich times and squirrelled away for poor times. Core GIK17925-3 also offers an opportunity to assess the impact of Zoophycos bioturbation on various palaeoenvironmental proxies. In this core, more than 30 % of the measured data points were more or less strongly affected by Zoophycos bioturbation. Together with the widespread occurrence this percentage indicates that Zoophycos may pose a serious threat to palaeoclimatic reconstructions in cores from low to moderate sedimentation rate sites.

The links between the Siberian Traps and the end-Permian mass extinction, and between the North Atlantic igneous province (NAIP) and the Paleocene–Eocene thermal maximum (PETM), demonstrate a critical role for large igneous provinces (LIPs) in the disruption of the Earth-surface carbon cycle (ESCC). High-precision ages for both volcanic provinces and the associated environmental crises show that, in both cases, the crisis was contemporaneous with the volcanism. The NAIP comprises two phases: the earlier Phase 1 (c. 61 Ma) and the much more voluminous Phase 2 (c. 56 Ma), linked to the opening of the NE Atlantic. The latter triggered the PETM, the largest Cenozoic hyperthermal. The Siberian Traps are significantly more voluminous than the NAIP, and triggered the end-Permian mass extinction. The masses of volcanic CO2 emitted from these provinces may have been much greater than previously suggested as substantial gas may come from intrusive bodies deep within the crust. Precursory warming due to the accumulation of volcanic CO2 in the atmosphere likely triggered the release of low-δ13C methane hydrate, although the masses of methane hydrate alone may have been insufficient to account for the observed temperature rises. The organic C was likely strongly supplemented by magmatically derived carbon and thermogenic carbon released during emplacement of sills and dykes into C-rich sedimentary units. More data are required on the volcanic flux rates in order to refine the cause–effect relationships between LIPs and the ESCC.

Three available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.

Plant fossils are described from the Cuche Formation, Eastern Cordillera, Colombia in the area of Floresta. Those identified as Colpodexylon cf. deatsii Banks and cf. Archaeopteris sp. suggest an earliest Late Devonian (Frasnian) age for the formation. These or similar taxa are also found in contemporaneous deposits in western Venezuela, and other elements of the Venezuelan flora are found in a geographically intermediate locality. All three Devonian plant localities in the northwest of South America are within the Colombian Eastern Cordillera and its northern extension, the Venezuelan Perijá Range, an area that has been integrated as a part of the so-called ‘Eastern Andean Terrane’ or ‘Central Andean Province’, supposedly accreted to the autochthonous block of the Guyana Shield during the early Jurassic or before. Although both invertebrates and plants from this terrane have strong affinities to North American and European assemblages, and might be interpreted as implying a Laurussian origin for the Eastern Andean Terrane, the evidence is not yet unequivocal, with some authors postulating an in situ development of this province.

The textures of the chilled marginal gabbro of the Skaergaard intrusion and of the coarser marginal gabbros 25 yards further in are described and related to counts of the number of separate crystals of the chief mineral species per cubic centimetre of the rock. An explanation of the textures and number of crystal individuals is attempted in terms of various degrees of supersaturation in the magma. In the chilled rock abundant nucleation of plagioclase and olivine, presumably at the middle labile stage of supersaturation, is inferred. This is followed by ophitic or poikilitic crystallization of pyroxene and ilmenite about scarce nuclei, produced at lower temperatures, presumably during the early labile stage of supersaturation for these two minerals. The coarser gabbro, further in from the margin, has about half the number of plagioclase crystals per cm.3 compared with the chilled rock and only one twenty-fifth the number of olivine crystals, and these have a tendency to be ophitic in texture. Under these slower cooling conditions, supersaturation apparently still reached into the middle labile region for plagioclase, giving many nuclei, while olivine, like pyroxene, separated under early labile supersaturation conditions and only relatively few nuclei formed. The contrasting textures of the plateau magma-type basalts of Mull and the tholeiitic basalts of Northern Ireland are explained along similar lines.

ONE of the objectives of the East African Archaeological Expedition of 1934–5 was the examination of the plateau north of Lake Eyasi—the Vogel River area—where, it was hoped, a continuation of the richly fossiliferous Oldowaya Middle Pleistocene lake beds would be found. This hope was essentially realized ; deposits with an interesting Middle Pleistocene fauna a little earlier than that of Oldoway were found, with the difference that they were entirely terrestrial. The development of precisely datable beds resting upon a main Rift Valley Scarp made possible a study of physiographical changes associated with the faulting.