A small micromonzonite pluton intruding Miocene extrusives of the Marysvale volcanic field of southern Utah has undergone a sequence of explosive brecciation, syenite veining, rheomorphism, calcium metasomatism and zeolitization. Skarn-like occurrences of magnetite and Al-spinel-rich feldspathoidal rocks within the outcrop are of two main types: (1) an olivine-bearing variety with occasional REE-rich minerals (zirconolite) occurs as veins and seams in desilicated latite screens and xeno-liths.; (2) an aluminous, corundum- and hibonite-bearing variety with accessory zirconolite, perovskite and armalcolite occurs mainly as fillings to the micromonzonite breccias. The chemically disparate types are interpreted as having initiated as propylitic, and argillic/alunitic, alterations of latite country rock in the early hydrothermal system of the pluton. Subsequent intrusion of the micromonzonite to higher levels has incorporated these products into the igneous complex, in which they have experienced varying degrees of nephelinization, pyrometamorphism, rheomorphism and veining.

A geochemical and mineralogical study of thin (2–20 cm) clay-rich beds found in Turonian–Coniacian chalks from the Anglo-Paris Basin has been undertaken. On the basis of their rare-earth element (REE) and mineralogical composition it is possible to subdivide beds into bentonites, characterized by a negative Eu anomaly and elevated smectite content, and detrital beds (characterized by a minimal or absent Eu anomaly and a greater proportion of illite). Six beds are considered to be bentonites (Glynde 1, Southerham 1, Caburn, Bridgewick 1, Lewes and Shoreham 2). Trace-element discriminant diagrams add support, as does comparison with similar studies undertaken in eastern England and northern Germany. Geochemical evidence demonstrates that the tephra was variably acidic in composition (rhyodacite–rhyolite–comendite/pantellerite), and was probably derived from crustal melting associated with initial rifting of the North Atlantic. Correlation of bentonites between the Anglo-Paris Basin, eastern England and northern Germany can be demonstrated and independently tested, establishing a tephro-event stratigraphy across northwest Europe for this period.

Lower Palaeozoic outcrops near Kemer comprise only Ordovician and Silurian strata in the Upper Antalya Nappes, and are described in detail for the first time. The oldest rocks, Seydişehir Formation (lower Arenig), resemble those of the central Taurides. A disconformity is probable, though unexposed, below the succeeding Şort Tepe Formation (Ashgill), a unit seen elsewhere only in south central and southeastern Turkey; sparse trilobites include Cyclopyge, Cyphoniscus, Panderia, Symphysops, Ulugtella, and one new species Placoparia (Hawleia) marcouxi. Silurian rocks (Sapandere Formation) differ from those further east in the Taurides, and are of Llandovery (Telychian), Wenlock and ?Ludlow age, based on conodonts, graptolites and trilobites (Cerauroides, Otarion (Aulacopleura), Sphaerexochus) the affinities of which lie with the Carnic Alps and western Europe. The Sapandere Formation is unconformably overlain by red sandstones at the base of the Armutlugözlek Formation (Devonian).

This paper evaluates four different methods that have been proposed for the estimation of the detachment depth beneath detachment folds. Guidelines are presented in order to use the most suitable method in a particular region deformed by detachment folds. These guidelines are constructed considering the assumptions of each method, the influence of different parameters on the estimation of the detachment depth (folding mechanisms, cross-sectional area variations, position and orientation of the regional datum, number of stratigraphic horizons, bed length and thickness, dip and position of the bounding lines, initial thickness of the ductile unit, single anticlines or fold trains) and the available data (ductile unit thickness, regional datum, detachment depth). Moreover, a new, simple method based on two previous methods is presented. The advantages of this new method are that the calculations are extremely simple and it uses information from more than one stratigraphic horizon; therefore, it does not depend strongly on the accuracy of the data at one level. The precision of the proposed methods is tested by their application to a number of natural and experimental single anticlines and fold trains. It appears that better predictions are obtained when analysing a complete detachment fold train than when dealing with a single detachment anticline. The reason might be that ductile material flow beneath the folds along the cross-sectional plane is taken into account when dealing with a long-enough cross section. We also suggest some hypotheses concerning what the shape and dimensions of the detachment folds indicate about the detachment depth in those cases where insufficient data are available to apply the methods proposed.

Wood-grained chert is an unusual type of banded nodular chert that is characterized by alternating thin dark-coloured bands and thicker light-coloured bands, which give the chert a texture reminiscent of the growth rings of wood. The wood-grained texture found in some chert nodules in the Portland Limestone Formation of southern England is the result of variations in the concentration of calcite inclusions within the chert. Light-coloured bands contain more abundant calcite inclusions than adjoining darker coloured chert bands. The Portland Limestone wood-grained cherts formed by the late diagenetic replacement of a highly compacted carbonate sand, in which abundant siliceous sponge spicules were the silica source. Oxygen and hydrogen isotope data (δ18O=27.0 to 29.3‰; δ18O=−71 to −91‰ V-SMOW), indicate that either chert formation or, more likely, the opal-CT to quartz transformation, occurred in meteoric or mixed marine and meteoric pore waters at temperatures in the range of 20–60°C. The wood-grained texture likely formed by a self-organization process. A feedback mechanism is proposed for the origin of the texture in which calcium and carbonate ions released during the replacement of the host limestone resulted in calcite supersaturation along the boundaries of growing chert nodule. Calcite inclusion-rich chert bands formed within the calcite supersaturated zone and inclusion-poor bands formed outside of the calcite-supersaturated zone. Wood-grained chert provides another example of how the coupling of reaction and transport can produce repetitive patterns in otherwise unordered sediments or rock.

High-resolution lithological and magnetic susceptibility logs were made of two sections of the Upper Llandovery Browgill Formation in northwest England: Stockdale Beck, the type section of the Browgill Formation, and Spengill. The Browgill Formation is composed of fine-grained deep marine siliciclastics, which can be divided broadly into two facies: a homogeneous grey mudstone, deposited under oxygenated bottom-water conditions, and subordinate beds of laminated, graptolite-bearing black mudstone deposited under low bottom-water oxygen levels. The latter facies is often partially or fully diagenetically altered to chlorite nodules, occasionally with manganese carbonate nucleii. Magnetic susceptibility logs are shown to reflect variations in the illite–chlorite ratio of the clay mineralogy. Chlorite is a paramagnetic mineral, so the bands of chlorite nodules produce magnetic susceptibility highs. Correlation demonstrates that diagenetically altered beds of laminated black mudstone are continuous between the two sections, now situated 32 km apart. This lateral continuity would favour pelagic fallout in preference to gravity flow as a depositional model for both facies. A correlated sequence within the turriculatus Biozone is 3.8 times thicker at Spengill than at Stockdale Beck, probably reflecting variations in sediment accumulation rates. Correlation also identifies significant non-sequences in both sections: at least 47% of the turriculatus Biozone (including maximus Sub-biozone) is missing at Stockdale Beck and at least 77% of the crispus Biozone is missing at Spengill. The identification of non-sequences may be of value for refining graptolite biostratigraphy.

More than 75% of heavy mineral spectra of Rhenohercynian greywackes from the Harz Mountains (Famennian–Visean), the Werra greywacke (Frasnian–Famennian) and the Rhenish Slate Mountains (Frasnian–Visean) contain small amounts of detrital chromian spinels. Similar grains have also been proven in sandstones of the Givetian Stiege beds (East Harz nappe). These sandstones are derived from the area of the Mid German Crystalline Rise, which is commonly interpreted as the source area of the Rhenohercynian greywackes. Microprobe analyses have revealed mainly a picotite composition. Presumable source rocks were chiefly Alpine-type peridotites. Due to the onset of spinel sedimentation in Givetian times, these peridotites must be at least partly of pre-Givetian age, and are assumed to be linked to Cadomian subduction. Potential source rocks are not exposed in the present outcrops of the Mid German Crystalline Rise nor in the Rhenohercynian zone or the Northern Phyllite zone, which implies that the presumed mafic to ultramafic lithologies were completely eroded and/or downfaulted during later stages of the Variscan orogeny.

Extensive sections in the Thorington gravel quarry complex in eastern Suffolk include the most complete record to date of sedimentary environments of the Westleton Beds Member of the Norwich Crag Formation. New palaeoecological and palaeomagnetic evidence is presented, which confirms that the Member was deposited at or near a gravelly shoreline of the Crag Sea as sea level fluctuated during a climatic ameloriation within or at the end of the Baventian/ pre-Pastonian ‘a’ Stage (Tiglian C4c Substage).

Seismic refraction profiles on land and marine single-channel seismic profiling in inshore waters were used to supplement shallow-borehole data to determine the overall form of the Quaternary sequence in the coastal zone of North Norfolk. Refraction data from five principal profiles across the zone shows four velocity units, and correlation with the borehole data indicates that these (principally) represent (a) the surface drained/weathered zone, (b) Holocene and glacial sediments, (c) weathered chalk, and (d) fresh chalk. A strong reflection on two marine profiles is interpreted as the top of the Chalk. Integration of the data shows that Quaternary sediments are contained in a broad, shallow, east–west trending trough centred along the marshes, landward of barrier sediments. This trough extends eastwards beyond the present shoreline into the southern North Sea. The linearity of the axis of the trough and the adjacent coastline suggests an underlying structural control that may be east–west faulting on the northern side of the London–Brabant Massif.