The Whitby Mudstone Formation in northeast England contains three shale facies (normal, restricted and bituminous) which have previously been differentiated on the basis of sedimentary structures and faunal assemblages. This paper shows that the three facies can also be differentiated by mineralogical, geochemical and microtextural criteria determined using BSEM, EDXRA, XRD and XRF. The bituminous shale facies consists of finely laminated shales containing an early diagenetic mineral assemblage dominated by pyrite, calcite and dolomite. The weakly laminated restricted facies shales contain an early diagenetic assemblage dominated by pyrite. The normal facies shales are very weakly laminated and contain siderite in addition to pyrite. The geochemical conditions which left a dominant early diagenetic imprint on the three facies are interpreted to be carbon-rich sulphidic, carbon-poor sulphidic and very carbon-poor sulphidic respectively.

Two-phase packets of crystals plus liquid form rapidly at a magma contact having a high thermal contrast with its surroundings. The packets can detach from an upper contact and settle rapidly with respect to crystal settling or turbulent stirring velocities. They carry crystals and supercooling downward and act as heat sinks for crystallization of floor cumulates. Evolution of picritic magma toward neutral buoyancy and overturn into overlying basalt magma proceeds most efficiently with two-phase convection. Sinking of hot bronzite-laden liquid into cooler anorthositic liquid destroys the liquid stratification within a day or so. Two-phase convection rarely yields crystal mush thicknesses suitable for compaction of cumulates, which occurs only for a narrow window of cooling rates. Two-phase convection leads to cool, thin boundary layers above and below hot interior magma and may tend to prevent or control turbulence. The critical timing and scale of two-phase layer detachment need further study.

Formations of Cambrian and Ordovician age originally identified by the letters A to E in the southern Amanos Mountains are reviewed using lithostratigraphic units known from the western Taurus Mountains and south-eastern Turkey. The youngest Cambrian rocks in the southern Amanos belong to the Sosink Formation and their age, based on trilobite evidence, ranges from the Badulesia Zone to the Solenopleuropsis Zone of the Middle Cambrian; they are overlain unconformably by conglomerates dated as Triassic? by means of plant fossils. Ordovician rocks – Seydişehir Formation (approx. Arenig) and Bedinan Formation (Caradoc in part) – are exposed further north, in the central Amanos. The unusual position of the allochthonous ophiolites, which rest in part directly upon Lower Palaeozoic rocks, is discussed.

The Siluro–Devonian suite of granitic plutons in the British Caledonides known as the Newer Granites, together with their associated extrusive rocks, represent one of the most extensively researched examples of calc-alkaline magmatism apparently related to orogeny. Although recent chemical studies have credibly interpreted some of the Scottish intrusions and volcanic rocks as part of a continental-margin magmatic arc generated by the subduction of lapetus oceanic lithosphere beneath Laurentia, insurmountable problems of distribution and timing arise when attempts are made to relate the magmatic activity as a whole to a traditional two-plate collision model for the orogeny.

Newer Granite magmatism is here discussed in the context of more mobilistic models for the post-Grampian evolution of the British Caledonides which involve E–W closure between Laurentia and Baltica, terminated by collision in the Silurian, followed by the northward accretion of Gondwana-derived terranes in the early Devonian. The former produced the Main Caledonian tectonometamorphism of the Northern Highlands of Scotland, the latter the Late Caledonian deformation of the slate belts in the paratectonic Caledonides. These models imply much more complex convergence geometries which can, in principle, account for the whole Newer Granite suite as a series of subduction-generated magmatic arcs overlapping in space and time.

The model proposed involves three late Caledonian magmatic arcs in addition to the Ordovician ‘Borrowdale arc’ which is not considered in this paper. One is related to Laurentia–Baltica convergence with westward subduction beneath the Scottish sector of the Laurentian margin in the Ordovician and Early Silurian, which generated the early members of the Newer Granite suite in the Highlands; a second is related to northward Silurian–early Devonian subduction at the Solway Line, which generated the younger Newer Granites and volcanic rocks north of the Highland Border; and a third, related to northward accretion of the Armorican terrane in early Devonian time, produced intrusive and extrusive magmatism as far south as Southeast Ireland and the English Midlands.

Small shelly fossils, especially conoidal microfossils, have potential for biostratigraphic correlation of Precambrian–Cambrian boundary rocks where evolutionary successions of taxa can be recognized. A succession of hyoliths, brachiopods and species of Sunnaginia, Torellella, Eccentrotheca and Rhombocorniculum can be recognized in the Home Farm Member of Nuneaton and/or the Comley Limestone of Shropshire, England. Revised ranges of taxa are given and Sunnaginia neoimbricata n.sp., S. parva n.sp., S. angulata n.sp., Eccentrotheca grandis n.sp. and several new records are described from Nuneaton and Comley. The similarity in the sequence of small shelly fossils in England and Siberia indicates that a correlation can be achieved between the two areas. It is suggested that the lower Tommotian to lower Atdabanian correlates with the Hartshill Formation of Nuneaton, of which the condensed Home Farm Member spans the mid Tommotian to lowest Atdabanian, while the upper Atdabanian to lower Botomian correlates with the condensed Comley Limestone of Shropshire.

The Coombadjha Volcanic Complex is the remnant of a Late Permian cauldron. It is part of an extensive sequence of silicic calc-alkaline volcanics that covers the southeastern portion of the New England Orogen in NSW. The Complex is elliptical, measuring 15 × 24 km, and is outlined by a ring pluton and an arcuate fault. Bedding in the volcanic units of the Complex defines a structural basin, with steep inward dips at the monoclinal rim and gentle to horizontal orientations near the centre. An older group of outflow ignimbrites, lavas, breccias and volcaniclastic rocks at least 1500 m thick, is conformably overlain by more than 500 m of texturally homogeneous, crystal-rich, dacitic ignimbrite. Ignimbrites of the older group are the products of several discrete eruptions from separate vents, all of which were situated outside the Coombadjha area. Silicic lava domes with volcaniclastic aprons, and a tuff ring, mark the positions of local vents active on a small scale during intervals between the emplacement of the outflow ignimbrites. No significant subsidence occurred, nor did a caldera exist at this stage. Cauldron subsidence occurred in response to the large magnitude eruption that produced the crystal-rich ignimbrite. The central cauldron block was lowered at least 2000 m by downwarping and fault displacement, and remained largely intact. There is no evidence for resurgent doming of the cauldron after subsidence, although igneous activity continued with intrusion of an adamellite ring pluton along much of the cauldron margin. The crystal-rich ignimbrite and the ring pluton are similar in composition and may have been successive products of a common magma source that sustained this simple, single cauldron cycle.

In situ observations of fossil and living specimens of the calcicolous mosses Bryum pseudotriquetrum, Cratoneuron commutatum and Catoscopium nigritum revealed very fast calcite depositional rates. Rhythmic layering in the fossil mosses corresponding with the seasonal climatic cycle suggests that the moss curtain occupied by these three mosses maintains the deposition of spongeous travertine layers at a mean rate of 4 cm a−1. A mean depositional rate of 4.2 cm a−1 may be calculated from measurements of the loss of bicarbonate from the springwater after it percolated through the moss curtain. These rates suggest that the 8 m high travertine terrace of Checa with a surface area of 800 m2 did not exist two millennia ago.

Mosses could be put to man's use for creating natural overgrowths on artificial surfaces, an idea based on an allusion by Wallner. He observed that the thread-forming, blue-green algae Vaucheria builds travertine deposits at an annual rate of 0.7–1.4 cm. We observed that the mosses Cratoneuron commutatum and Bryum pseudotriquetrum may form spongeous travertine layers at respective maximum rates of 11 and 14 cm a−1. This would reduce the time required to build natural overgrowths on artificial objects to a practical period of months.

Eight new K-Ar determinations are presented which, together with field relations and previous studies, are used to construct a chronology of the volcanic build-up of Fuerteventura. The earliest island-building volcanics are late Cretaceous to early Tertiary alkaline basaltic volcaniclastic sediments, and these may be correlated with the early gabbro/pyroxenite intrusions which were probably subvolcanic to the early edifice. This was followed by a carbonatitic subvolcanic complex then by two later high-level gabbro/pyroxenite plutons, the latter being early Miocene or older. The emplacement of a subsequent middle Miocene gabbro/syenite ring complex caused widespread resetting of the Ar contents of the earlier rocks, but nevertheless consideration of the mineralogy of the rocks in conjunction with the field relations enables the long volcanic history (c. 80 Ma) to be reconstructed.

Chlorite–mica stacks in the Wenlock turbidites have been studied using backscattered electron microscopy and electron microprobe analysis, combined with thin-section work and bulk rock chemical analysis. The stacks occur in fine sandstones and silt–mud turbidites and range in length from < 30 μm to 1.5 mm. They consist of interlayered packets of Fe-rich chlorite and mica.

Combined textural and chemical data suggest that many of the stacks represent altered detrital biotite micas. A four-stage alteration sequence is proposed:

(1) Subaerial alteration of biotite, in the source area, to interlayered biotite–hydrobiotite/vermiculite.

(2) Post-depositional collapse of vermiculite to form a mica phase under conditions of high K+/H+ in the sediment pore waters.

(3) Decrease in K+/H+ ratio, possibly due to H+ build up in the fermentation zone, causing alteration of biotite layers to chlorite.

(4) Kinking of the stacks and pressure solution of chlorite early in the development of cleavage.

The second derivative of gravity anomalies of the Qattara area was analysed and statistically studied for determining the tectonic elements. Zones of zero second derivative were considered as the locations of possible faults. The analysis of a constructed tectonic map portrays the predominance of N45°W, N85°E and N45°E fault trends in addition to less pronounced N15°E and N–S faults. The NW–SE faults are very old and inherited from the basement structures. They acted as first order right-lateral wrench faults during the Alpine tectonism. Second and higher orders of faults, developed as a consequence of these movements, are represented by the N85°E and other less abundant trends. Vertical movements along the existing fault system, in addition to the horizontal displacement, is supported by the analysis of the pronounced anomalies of the second derivative map. The subsurface structural picture of the area is composed of uplifted and downfaulted adjoining blocks.