A detailed carbon- and oxygen-isotope stratigraphy has been generated from Upper Cretaceous coastal Chalk sections in southern England (East Kent; Culver Cliff, Isle of Wight; Eastbourne and Seaford Head, Sussex; Norfolk Coast) and the British Geological Survey (BGS) Trunch borehole, Norfolk. Data are also presented from a section through the Scaglia facies exposed near Gubbio, Italian Apennines. Wherever possible the sampling interval has been one metre or less. Both the Chalk and Scaglia carbon-isotopic curves show minor positive excursions in the mid-Cenomanian, mid- and high Turonian, basal Coniacian and highest Santonian–lowest Campanian; there is a negative excursion high in the Campanian in Chalk sections that span that interval. The well-documented Cenomanian–Turonian boundary ‘spike’ is also well displayed, as is a broad positive excursion centred on the upper Coniacian. A number of these positive excursions correlate with records of organic-carbon-rich deposition in the Atlantic Ocean and elsewhere. The remarkable similarity in the carbon-isotope curves from England and Italy enables cross-referencing of macrofossil and microfossil zones and pinpoints considerable discrepancy in the relative positions of the Turonian, Coniacian and Santonian stages.

The oxygen-isotope values of the various Chalk sections, although showing different absolute values that are presumably diagenesis-dependent, show nonetheless a consistent trend. The East Kent section, which is very poorly lithified, indicates a warming up to the Cenomanian–Turonian boundary interval, then cooling thereafter. Regional organic-carbon burial, documented for this period, is credited with causing drawdown of CO2 and initiating climatic deterioration (inverse greenhouse effect). Data from other parts of the world are consistent with the hypothesis that the Cenomanian–Turonian temperature optimum was a global phenomenon and that this interval represents a major turning point in the climatic history of the earth.

A single slab of silicified silty and cross-bedded mudstone from the Katkoyeh Formation, east-central Iran yields Yutagraptus cf. mantuanus Riva which indicates a late Arenig age. The slab also bears Dictyonema ghodsiae sp. nov., regarded as the only unequivocally planktonic dendroid from post-Tremadoc strata. The sicula is surrounded by at least twelve vesicular bodies which constitute a raft of floats. These are the only certain floats yet identified in the Order Dendroidea, and one of very few cases known in the Class Graptolithina.

Several rock stratigraphic successions, metamorphosed and non-metamorphosed, are found to be similar and/or identical with each other across the so-called ‘Main Zagros Thrust’. Stratigraphic successions form thin allochthonous sheets carried from northeast to southwest by numerous low-angle thrust faults of either ductile to brittle-ductile type or brittle type. Similarities in lithic and faunal characteristics of the stratigraphic units and in the style of structural deformation across the ‘Main Zagros Thrust’ imply that either the suture between the Afro-Arabian and Iranian lithospheric plates is not located in the Nahavand region or, if it is, it must be buried under several thrust sheets.

Thin, subplanar or parallel-sided syntectonic quartz veins from the Hodgkinson Province, North Queensland, Australia contain mica inclusions that are identical to wallrock mica textures. These ghost textures can only be produced by incomplete replacement of the wallrock by quartz. The planar form of the veins indicates that there was a planar control on their formation. We propose that the veins formed around syntectonic fractures that localized silica micrometasomatism of the fracture wall. The formation of the veins can be explained by a model which involves fracture of the wallrock, reaction between the fracture wall and the ambient metamorphic fluid and eventual sealing of the fracture by precipitation from the fluid. The new vein is then a locus of further fracture. Replacement of wallrock micas occurs via a two-stage process where biotite is replaced by muscovite, which is in turn replaced by quartz. We propose the term crack–reaction to describe the resulting cyclic process because it can be compared with the crack–seal model of vein formation. Crack–seal and crack–reaction are different only in the relative amounts of metasomatism and precipitation that occur subsequent to fracture and can be envisaged as end members of a more general vein-forming process.

Radiolaria were examined throughout the Plio-Pleistocene of Deep Sea Drilling Project (DSDP) Site 609. Eight radiolarian datum-levels (first and last appearances) were identified, some for the first time in the North Atlantic. The recognition of these datums allows correlation between the Atlantic, Pacific and Indian oceans, through a previously published zonal scheme (Johnson et al. 1989). Zones NR1 to NR11 were recognized, although some zones had to be combined (NR1–2 and NR8–10) due to the absence of some stratigraphically important taxa. The relative abundance distribution of the radiolarian palaeoceanographical proxy Didymocyrtis tetrathalamus indicated three cool phases (0/0.56–0.75 Ma, 1.2–1.33/1.69–1.86 Ma, and 2.14–2.32/3.73– > 4.1 Ma) interrupted by two relatively warm episodes (0.56–0.75/1.2–1.33 Ma and 1.69–1.86/2.14–2.35 Ma). These fluctuations in sea-surface temperature (SST) correspond with palaeoclimatic events indicated by other proxies (e.g. Foraminifera), such as the onset of Northern Hemisphere glaciation. This study illustrates the usefulness of radiolaria in North Atlantic stratigraphical and palaeoceanographical analysis.

The geometry and kinematic evolution of a frontal ramp section associated with the Tertiary West Spitsbergen Orogenic Belt has been investigated in a small area (Lappdalen) north of Isfjorden. The previously recognized thrust front corresponds to a complex step or ramp in the position of the sole-thrust in the area. The sole-thrust is localized to the evaporites of the Permian Gipshuken Formation to the west of the footwall ramp, whereas to the east it continues as a bedding-parallel thrust in Triassic shales (Sassendalen Group). The area to the west of the footwall ramp is characterized by large scale thrusts and folds involving the Permian Gipshuken and Kapp Starostin formations and the lower part of the Triassic Sassendalen Group. East of the footwall ramp both Permian and Triassic strata are sub-horizontal and apparently undeformed. Three major thrust sheets are recognized. Based on the geometric relationship between folds and faults in the area, both fault-bend and fault-propogation mechanisms of folding are inferred. Restoration of the Kapp Starostin Formation to its pre-deformational state indicates a minimum of 35% shortening. Structural observations within the Sassendalen Group in the study area and on Dickson Land suggest that some of this shortening is transmitted eastwards along one or more bedding parallel thrusts in the Sassendalen Group.

An assemblage of fossil plants is here recorded from the Middle Devonian Beacon Heights Orthoquartzite and overlying Aztec Siltstone (Taylor Group), of the Cook Mountains and Skelton Névé regions, southern Victoria Land, Antarctica. The Beacon Heights Orthoquartzite exposed in the southern Cook Mountains yielded specimens of the lycopods Haplostigma lineare, Malanzania sp., and Archaeosigillaria sp. cf. A. caespitosa. The Aztec Siltstone flora contains Praeramunculus alternatiramus and H. lineare.

The well-preserved Tvären crater is noteworthy for being one of a small number of Early and Middle Ordovician impact structures formed in a marine environment. It is demonstrated to be an impact structure by the presence of a breccia lens, consisting of crystalline basement rocks, and shocked quartz. The breccia lens formed under dry-hot conditions after expulsion of sea-water by the impact. Resurging sea-water thereupon deposited a positively graded, 60 m thick turbidite-like unit. This graded resurge deposit is a previously unknown feature, to be expected in open-sea impacts. Breccia in the lower part of this graded deposit contains fragments of a remarkably complete orthoceratite limestone succession that existed at the site of impact, resting on non-lithified sand of probably Early to earliest Middle Cambrian age. A sedimentary succession was deposited inside the crater at depths decreasing from more than 200 m in the initial stages to some 100 m at the time of deposition of the youngest preserved beds. The environment within the crater thus favoured deposition of an essentially complete stratigraphic succession with depth-controlled palaeoecology for a significant time interval after the impact. Whereas planktonic members, like graptolites and chitinozoa, are present throughout the post-impact succession, and asaphids, almost as persistent, became established at an early date, burrowers were somewhat reluctant to enter and remopleuridids and small strophomenids came in at a late stage. We suggest as a result of this study that structures formed by impact may offer unique information about the palaeogeology and palaeoenvironment of the region hit by the impact.

The Sunnfjord Melange is a strongly tectonized sedimentary assemblage occurring tectonostratigraphically below the Solund–Stavfjord Ophiolite Complex of Ashgill age, and upon continental margin deposits of Wenlock or older age. The Sunnfjord Melange, which probably started to form within an oceanic transform fault, developed further during obduction of the Solund–Stavfjord Ophiolite Complex. The Sunnfjord Melange is divided into two units, the lower Øyravatn Unit of predominantly fine grained calcareous quartz-bearing chlorite–muscovite schists, and the upper Markavatn Unit, mainly metagreywackes. Both units contain blocks of metabasalts, marble and meta-arkose. Serpentinite blocks are restricted to the Markavatn Unit. The appearance of serpentinite detritus is marked by much higher contents of Cr and Ni in the metasediments of the Markavatn Unit than in those of the Øyravatn Unit. The geochemistry of the metasediments from the Øyravatn Unit and the Markavatn Unit is compatible with mixing of detritus from continental and ophiolitic sources. Despite the strong and pervasive deformation of the Sunnfjord Melange, its geochemical composition from the lowest to the highest tectonostratigraphic levels reflects that of the inverse pseudostratigraphy of the Solund–Stavfjord Ophiolite Complex. Thus, only metabasalts of the Solund–Stavfjord Complex and continental meta-arkoses yielded detritus to the schists of the Øyravatn Unit. The compositions of the schists and metagreywackes of the Markavatn Unit, on the other hand, show that a multicomponent detritus derived from metabasalt and serpentinite of the Solund–Stavfjord Ophiolite Complex, mixed with the detritus from continental meta-arkoses.

Broad zones of distributed shear operating through mid-crustal regions of orogenic belts may incorporate narrow horizons of intense localized deformation culminating in discrete, large magnitude displacements. The relative importance and relationship between distributed and localized shear are influenced by a variety of factors including lithological variation, pre-existing structural anisotropy, strain rate and migration of fluids. Rigorous structural analysis of lower amphibolite facies Dalradian metasediments in northwestern Ireland demonstrates that an early (D1) discrete ductile detachment was subsequently reactivated during distributed non-coaxial D2 deformation operating in a broad zone through the structural pile. Regional shear was directed towards the southeast and resulted in the generation and translation of kilometre-scale, isoclinal, recumbent sheath folds which close and face towards the transport direction. The D1 detachment is clearly folded around the hinges of these major folds, whilst on fold limbs it was reactivated and acted as a local décollement within the zone of distributed shear. Shear criteria along the detachment indicate a southeast-directed translation of the major folds, in sympathy with regional shear. A broad zone of D3 translation operating through the nappe pile resulted in coaxial refolding of large scale F2 folds by the D3 Ballybofey Nappe producing a complex fold interference pattern. Non-coaxial D3 deformation resulted in continued reactivation of local decollements, together with the initiation of east-southeast directed oblique thrusts and partial dismemberment of D2 folds. Detailed structural investigation allows concepts of distributed and localized shear to be evaluated and models of crustal deformation to be assessed.