The folds in the Taurus–Zagros Belt of northern Iraq have generally been considered to be decollement buckle folds. This implies the presence of a decollement horizon at or near the base of the sedimentary cover, the ‘Infra-Cambrian Hormuz Salt’ and a passive role of the Precambrian basement in the tectonic evolution of the folded belt. Structural, stratigraphic, geophysical and remote sensing evidence suggests that forced folding, due to faulting in the basement, has played a significant role in the development of many of the folds in this region. This is clear from the substantial evidence of basement faulting, the lack of any convincing evidence for the presence of an extensive and regional decollement horizon (i.e. the Hormuz Salt) between the basement and the cover rocks, and the geometries of the folds and related mesostructures. The study shows that in the Taurus Foothills Zone, the folds are short, oval in plan shape, and arranged in an en echelon pattern along two sets of dislocation zones in the basement. However, the folds in the Zagros Foothills Zone are longer, linear and arcuate in plan shape. Many of the studied folds show similar features to those observed in the Rocky Mountains, U.S.A.

Calcite-rich carbonatites are commonly attributed to calcitization of alkalic carbonatite of Oldoinyo Lengai type. The interpretation arises from the presumption that magmatic crystallization of calcite at atmospheric pressure is not possible. We show that only a small percentage of fluorine, a common element in carbonatite magmas, permits such crystallization, and we argue that most of the calcite in extrusive carbonatites is magmatic. The presence of any more than minor apatite precludes an alkalic carbonatite parentage. While not denying that calcification of alkalic carbonatite can occur, we suggest that it is not generally responsible for the formation of extrusive calcific carbonatites.

The Lake Ambrose volcanic belt (LAVB) outcrops as a 45 km long northeast-trending belt of mafic and felsic volcanic rocks along the eastern side of the Victoria Lake Group in south-central Newfoundland. It comprises roughly equal proportions of mafic pillow basalt and high silica rhyolite, locally interbedded with epiclastic turbidites. Volcanic rocks have been metamorphosed in the greenschist facies and are extensively carbonatized.

U-Pb (zircon) dates from rhyolite at two, widely separated localities give identical ages of 513 ± 2 Ma (Upper Cambrian), and this is interpreted as the eruptive age of the volcanic sequence. Primitive arc and low-K tholeiites can be recognized on the basis of major and trace element geochemistry, ranging from LREE-depleted to LREE-enriched. Geochemical variation between mafic volcanic types is interpreted predominantly to reflect contrasts in source characteristics and degree of partial melting; some variation within each geochemical type attributable to fractional crystallization can be recognized. Detailed examination of some samples indicates that the heavy REE and related elements have locally been mobile, probably as a result of carbonate complexing.

The LAVB is the oldest well-dated island arc sequence in Newfoundland, and perhaps in the Appalachian–Caledonian Orogen. Its age requires modification of widely held models for the tectonic history of central Newfoundland. It is older than the oldest known ophiolite, demonstrating that arc volcanism was extant before the generation of the oldest known oceanic crust in this part of Iapetus. It further demonstrates that there was a maximum of approximately 30 Ma between the rift-drift transition which initiated Iapetus, and the initiation of subduction. This suggests that the oceanic sequences preserved in Newfoundland represent a series of arcs and back arc basins marginal to the main Iapetus Ocean, and brings into question whether the Appalachian accreted terranes contain any remnants of normal mid-ocean ridge type Iapetan crust.

The Caledonian Sunnhordland Batholith comprises calc-alkaline plutons that have been assigned to three units according to their relative age and composition: a gabbro-diorite unit, a granodiorite unit and a later granodiorite-granite unit. The batholith was emplaced into an envelope including ophiolite and island-arc complexes, sediments and volcanites of early Ordovician age that were developed in a zone of plate convergence. Continued convergence resulted in the formation of a mature magmatic arc and a thickened crust; the late granitoids (unit 3), which commenced their crystallization at pressures around 6 to 7 kb, rose as permitted diapiric intrusions. The ingress and ascent of the magmas in this setting is considered to have been facilitated by the presence of major shear zones developed in relation to plate convergence. In this model, plastic instabilities were formed in an otherwise elastic middle and upper crust. Non-coaxial deformation was accelerated by the emplacement of magmas and the formation of abundant partial melts in water-rich sediments of the envelope. The deformation, which was accelerated by magma and melt lubrication in aureoles, controlled both the shape and internal structure in the gabbro and granodiorite plutons.

The Asenvågoya Conglomerate is a thin (c. 6 m) conglomeratic body composed of mass-flow deposits and enveloped by braided-stream sandstones and conglomerates. The section studied represents the proximal part of a small-radius alluvial fan built out from the basin margin towards a flood basin. The fan was possibly generated by escarpment creation, or rejuvenation, in response to syndepositional faulting along the basin margin, and comprises sand-matrix-supported and clast-supported, sheet-like conglomerates. There is an upward change through the sequence from stream flow and surging mass-flow, through fully turbulent mass-flow and sheet flow to cohesive mass-flow deposits and then a return of braided-stream alluvium at the top of the sequence. The fan wedge demonstrates the wide range of textures possible within a ‘mass-flow” system.

The isotopic composition of Sr and Nd together with the abundance data for major and trace elements are reported for Tertiary to Quaternary volcanics from a variety of localities in western Turkey. These data are used to evaluate the role of crust–mantle interaction in the petrogenesis of the western Turkish volcanics. The major and trace element chemistry reveals a general change in the nature of volcanism from dominantly calc-alkaline in Tertiary to alkaline in Quaternary times. The calc-alkaline rocks are quartz-normative and comprise andesitic to rhyolitic compositions of Miocene–Pliocene age; the trace element patterns are typical of continental margin volcanics with high Ba/Nb ratios and negative Ti anomalies. The alkaline rocks are nepheline-normative and dominantly Quaternary in age; they are basic in composition, with a change from potassic nature in Miocene–Pliocene to sodic in Quaternary times. Most of the Tertiary alkaline volcanics display trace element patterns similar to those of the calc-alkaline ones, whereas the Quaternary alkaline volcanics have low Ba/Nb ratios without negative Ti anomalies; they resemble intraplate volcanics.

The calc-alkaline rocks have high 87Sr/86Sr (from 0.705011 to 0.709529) and low 143Nd/144Nd ratios (from 0.512294 to 0.512691). With the exception of two Tertiary samples, all the alkaline volcanics plot within the so-called mantle array of the isotope correlation diagram, 87Sr/86Sr ratios ranging from 0.703128 to 0.703628 and 143Nd/144Nd ratios ranging from 0.512749 to 0.512998. The two Tertiary alkaline samples, with trace element patterns similar to those of the calc-alkaline ones, have considerably higher Sr (0.707741–0.707918) and lower Nd (0.512494–0.512514) isotope compositions. The combined isotope and chemical data suggest the derivation of the western Turkish volcanics from variable mixtures of melts generated in two different mantle regions. The calc-alkaline volcanics were essentially derived from the continental lithospheric or shallow asthenospheric mantle which was contaminated with upper crustal material during earlier subduction events. The generation of the alkaline volcanics was controlled by melts derived from relatively deep, isotopically depleted mantle regions. Most of the volcanics were subjected to contamination at crustal levels, through the operation of an assimilation–fractional crystallization (AFC) process. The nature of contaminant changed from upper crustal in the calc-alkaline to lower crustal in the alkaline volcanics, accompanying the overall decrease in the amount of contamination from about 50% down to about 10%, and broadly paralleling the transition from compressional to extensional tectonics in the region.

High-magnesian andesites outcrop in a subvolcanic complex in the island of Skyros in the central Aegean Sea. Mineralogical indicators of this high-Mg content include bronzite and clinopyroxene phenocrysts, the former with high Cr2O3, and some phlogopite. Plagioclase (oligoclase–andesine) and Fe–Ti oxides were late phases to appear at the liquidus. Whole-rock geochemistry shows trace element features similar to those of subduction-related rocks. Radiometric dating indicates an early Serravallian (middle Miocene) age, approximately synchronous with the onset of post-orogenic rifting and extension of the Aegean Sea. This tectonic setting is consistent with an origin by adiabatic decompression of mantle peridotite previously modified by subduction-related fluids.

Volcanic activity, the result of crustal differentiation during the Hercynian orogeny, generated eight explosive eruptions in the Vilancós region of the Spanish Pyrenees. The volcanic products comprise the Erill Castell Volcanic Formation of Stephanian age, which crops out as a 20 km long, WNW-trending strip < 2 km wide dipping steeply to the south.The Vilancós region represents a small fragment of an originally extensive regional terrain of silicic centres.

The explosive eruptions mainly generated strongly peraluminous and phenocrystal garnet-bearing subaerial ignimbrite facies. Proximal intra-formational breccias represent a substantial volume of the preserved erupted product and one phreatoplinian deposit is exposed. Mass-flow deposits are common, and small-volume basalt, andesite and rhyolite lava flows, minor tuffs and palaesols also occur.

Electron microprobe data show that each garnet-bearing member of the Vilancós region has a distinct garnet composition. This is used as geochemical fingerprinting tool to aid mapping and correlation between proximal intra-formational breccias and ignimbrite of the same eruption. Within one debris-flow deposit (the Vilancós Breccia Member) at least three garnet populations occur. Two of these are derived from pyroclastic members within the mapped region, the other comes from an unexposed rhyolite lava source.

Subtidal columnar stromatolites up to 2.5 m high near Lee Stocking Island in the Exuma Cays, Bahamas, have surface mats approximately equally composed of algae and cyanobacteria. The stromatolites are composed of fine–medium oöid and peloid sand. This sediment is supplied to the growing stromatolite surfaces by strong tidal currents which lift grains into suspension and sweep migrating dunes over the columns. The algae include an unidentified filamentous chlorophyte, and numerous diatom species mostly belonging to Mastogloia, Nitzschia and Navicula. The dominant cyanobacteria are two oscillatoriacean species, both probably belonging to Schizothrix. Trapping of sediment is mainly effected by the unidentified chlorophyte which is veneered by epiphytic diatoms. Grains are bound into a mucilaginous mat composed of diatoms and cyanobacteria. Cyanobacteria alone would not be able to trap and bind coarse sediment so effectively in this environment. In being coarse-grained and having a significant eualgal component to their mats, these stromatolites are similar to subtidal columnar stromatolites at Shark Bay, Western Australia. The Lee Stocking stromatolites are physically stressed by high velocity tidal currents and mobile sediment. The Shark Bay stromatolites are stressed by hypersalinity. In both cases stress deters grazers, encrusters and bioeroders. These coarse-grained eualgal stromatolites contrast with micritic and predominantly prokaryotic stromatolites of most Recent marine environments, and are not analogues for most pre-Phanerozoic stromatolites. They appear to be a response to changing stromatolitic mat components in the Cenozoic.

Cathodoluminescence (CL) examination of Recent biogenic carbonates shows that they are often luminescent regardless of their mineralogical composition (calcite v. aragonite), habitat (marine v. fresh water), way of life (sessile v. vagile) or environment (hyper- v. hyposaline water). Thus, the presence of luminescence in biogenic particles is not a reliable indicator of diagenetic alteration as some authors have suggested. In addition, CL can reveal variations in the mineralogy of shell material (e.g. regenerated calcitic v. primary aragonitic) and can highlight growth-related structures. Manganese (Mn2+) is the most likely activator of this luminescence, and its content in the shells of benthic organisms seems to be linked to growth rate, ontogeny, open sea conditions, bathymetry and salinity. In neritic environments the Mn2+ content and the CL of molluscs and foraminifera appear to increase with decreasing salinity. This study indicates that CL may be an important tool for the determination of environmental and ontogenetic parameters in biogenic carbonates in addition to its current use indiagenetic studies.

The presence of polyphase shear zones transected by several suites of dolerite dykes in Archaean basement of the Vestfold Hills, East Antarctica, allows a detailed reconstruction of the local structural evolution. Archaean and early Proterozoic deformation at granulite facies conditions was followed by two phases of dolerite intrusion and mylonite generation in strike-slip zones at amphibolite facies conditions. A subsequent middle Proterozoic phase of brittle normal faulting led to the development of pseudotachylite, predating intrusion of the major swarm of dolerite dykes around 1250 Ma. During the later stages and following this event, pseudotachylite veins were reactivated as ductile, mylonitic thrusts under prograde conditions, culminating in amphibolite facies metamorphism around 1000–1100 Ma. This is possibly part of a large-scale tectonic event during which the Vestfold block was overthrust from the south. In a final phase of strike-slip deformation, several pulses of pseudotachylite-generating brittle faulting alternated with ductile reactivation of pseudotachylite.

A rich fauna dominated by trilobites and calcified chordates has been collected in Shropshire from the Arenaceous Beds, the highest member of the Tremadoc Shineton Shale Formation, and hitherto regarded as poorly fossiliferous. This fauna shows that shelf conditions persisted longer in Shropshire than has been supposed. It is likely that even younger Tremadoc is cut out at the unconformity below the Caradoc in the Shineton Inlier. The correlation of the later Tremadoc is reviewed, and the nomenclature of British Tremadoc biozones is revised. The trilobites described here are a mixture of previously known and new forms. The name Shumardia (Conophrys) salopiensis Callaway is revived for British material traditionally assigned to the Scandinavian species Shumardia pusilla (Sars), from which it is distinct. The new taxa Litagnostus meniscus sp.nov., Apatokephalus sarculum sp.nov. and Skljarella cracens sp.nov. are described. The type species of Asaphellus, A. homfrayi and Leptoplastides, L. salteri, are redescribed, and Geragnostus callavei, Pseudokainella impar, and Parapilekia sp. are recorded. New information on the ontogeny of S. (C.) salopiensis and A. homfrayi is given. Litagnostus and Skljarella are recorded from the British Isles for the first time.

Late Permian Karoo deposits of the northern Selous Basin in south-central Tanzania comprise conglomerates and diamictitic boulder beds of alluvial and scarp-foot fan origin. These merge with grey to greenish sandstones, siltstones and black shales of deltaic and lacustrine environments. Microflora assemblages indicate a late Permian age. Lateral changes and interfingering of various lithofacies units are common. Depositional development was controlled by syndepositional faulting and variations of gradients resulting from fault movements. The position of the fault scarp separating the basin area from the elevated basement horst to the west roughly corresponded with the present boundary between the Selous Basin and the Precambrian metamorphics of the Uluguru Mountains.

The late Permian Karoo succession of this part of the Selous Basin apparently overlaps older Karoo deposits contained in the north-northeast trending narrow graben structures. It is therefore regarded as a new depositional event which was initiated by renewed tensional tectonism in late Permian time. During this tectonic episode the narrow early Karoo graben structures were expanded into much broader rift basins. Material eroded from the rift shoulders and associated highlands was literally dumped across the fault scarps, forming debris aprons and scarp-foot fans. Rivers emanating from the highlands formed large alluvial fans and, further afield, deltas issued into freshwater lakes.

Some of these late Permian faults were rejuvenated by late Cretaceous to early Tertiary tectonism. Thermal waters circulating along fractures converted feldspars, biotites and hornblendes to prehnite. Further tectonic adjustments in mid Tertiary time led to the present-day morphology.

The Wedza–Mimosa platinum deposit is a loosely stratiform PGE-rich sulphide zone (MSZ) set within a complexly layered, shallow synclinal sequence of pyroxenites and gabbros. Both the MSZ and its host rocks display systematic stratigraphic, lithological and compositional variations between the margins and the axis of the deposit. A well preserved marginal facies is characterized by discordant layering, stratigraphic complexity, evidence of non-equilibrium crystallization, magmatic erosion and extensive pegmatoids, as well as by irregular MSZ development and metal contents. The principal transverse variations and marginal phenomena are interpreted in terms of the high transverse heat flux and heat gradient caused by the narrow trumpet-like cross-sectional structure of the original magma chamber, the magma replenishment process, the angular relationship between the chamber floor and the stratified magma, and the increase in magma density caused by the onset of plagioclase crystallization.

In northern Euboea, central eastern Greece, an up to 3 km-thick polygenetic melange (Pagondas complex) is structurally interleaved between a Triassic–Jurassic carbonate platform (Pelagonian Zone) and an overriding harzburgitic ophiolite. The melange mainly comprises late Triassic shallow-water limestone and calciturbidites, radiolarites, Triassic–Jurassic tholeiites, alkaline basalts and minor andesites. The units concerned range from kilometre-sized thrust sheets, and detached blocks, to broken formation and structureless, or bedded matrix-supported conglomerates (diamictite). The melange includes remnants of Neotethyan oceanic lithosphere, overlain by radiolarites, hemipelagic carbonates and distal calciturbidites derived from a Mesozoic carbonate platform. Tholeiites were erupted at a Triassic–Jurassic spreading axis, whilst within-plate-type alkali basalts are interpreted mainly as seamounts. Kilometre-scale detached blocks of shallow-water coralline limestone are identified as collapsed atolls, formed within an ocean and/or along the rifted continental margin. Volcaniclastic sediments are locally interbedded with radiolarite, and reflect post-volcanic erosion of the ocean floor. Intra-oceanic convergence began, apparently in late early Jurassic time, giving rise to the Euboea ophiolite above an inferred westwards-dipping subduction zone. The Pagondas Complex then developed as an accretionary prism. The subduction trench later collided with the Pelagonian passive margin, driving the hot Euobea ophiolite over the accretionary complex, to produce amphibolites and greenschists of the metamorphic sole. Trench–margin collision then drove the entire supra-subduction zone complex, apparently eastwards, downflexing the Pelagonian carbonate platform to form a foredeep in which late Jurassic (Kimmeridgian–Tithonian) radiolarian sediments accumulated. During emplacement, the accretionary complex was disrupted and partly resedimented as debris flows, turbiditic volcaniclastic sandstone and shale in a foredeep, or foreland basin setting.

New trepostomatous bryozoan species, Paralioclema winsnesi sp. nov., Paralioclema mariaholmensis sp. nov. and Paralioclema sp. cf. mariaholmensis are described from the Lower Triassic succession of Spitsbergen. The investigated bryozoan faunas are associated with coarse sandstones, calcareous siltstones and shelly limestones. The bryozoan colonies are mostly well preserved in situ, and show limited evidence of transportation. Some zoarial fragments show bioerosion. The conodont species Neogondolella elongata, Ellisonia triassica, Neospathodus dieneri and Neospathodus svalbardensis extracted from the investigated horizons are Dienerian–Smithian in age.

Schaubcylindrichnus, a distinctive sheaf of arcuate, well lined, congruent dwelling tubes, although poorly known in general, is a good indicator of shoreface depositional settings for many Cretaceous rocks of the United States. Until recently, in fact, it was known only from those rocks; but it has now been recognized in Tertiary rocks of Taiwan, possibly in slightly more distal depositional settings. In addition to its distinctive morphological and environmental significance, the ichnogenus also may have substantial biostratigraphical significance. Further reconnaissance is needed to confirm these seemingly unique distributions, that is, to help explain why the trace fossil so far seems to be restricted to certain Cretaceous rocks in North America and certain Tertiary rocks in Asia.

In north Pakistan cooling history data show that metamorphism within the Indian Plate predated 40 Ma, and that the post-metamorphic thrust stack developed within the crystalline internal zones had cooled to less than 100 °C by c. 18 Ma. Much of this cooling occurred during late Oligocene to early Miocene time and can be equated to substantial unroofing of the metamorphic pile. This unroofing was by a combination of erosion, recorded in Lower Miocene molasse deposits within the foreland basins, and by large scale hinterland (northward) directed extensional normal faults developed within the upper parts of the Indian Plate and within the Kohistan–India suture zone and operative as late as 20 Ma. As up to 20 km of material was removed during exhumation, substantial uplift must have been synchronous with exhumation. Part of this may be accounted for by isostatic rebound of the thickened Indian Plate, and part by uplift in the hanging wall of major south-verging thrusts developed at the base of the crystalline pile.

Laser ablation techniques permit the determination of the stable isotopic ratios of finely crystalline calcite cements in chalks for the first time. Modelling of fluid–rock interaction using whole rock and laser ablation stable isotopic data indicates that carbonate mineral diagenesis in the Eldfisk Field consisted largely of the dissolution and reprecipitation of calcite with little associated loss of porosity. Cementation by calcite derived from stylolites apparently occurred throughout the Eldfisk Field chalk, but had only a subsidiary effect on whole rock isotopic ratios. Oxygen isotopic data indicates a pore water temperature of 50–80 °C during the bulk of chalk recrystallization. Increases in whole rock δ13C values with depth are likely the result of bacterial methanogenesis during chalk recrystallization.

Didymograptus (s.l.) rigoletto sp.nov. is a distinctive species in the balticus group of didymograptids occurring in the Tøyen Shale (Lower Ordovician). In three localities in Sweden it has a short range near the top of the range of Tetragraptus phyllograptoides, and it occurs at about the same level at localities in the Oslo region, Norway; at most of these localities it occurs within the range of Tetragraptus of the approximatus group. Its presence in the Skiddaw Group of the English Lake District indicates the occurrence there of the basal Arenig (sensu lato), equivalent to the T. phyllograptoides Biozone of Scandinavia and the T. approximatus Biozone (= Lancefieldian 3) of the Australasian succession.