Field studies on the island of Elba and seismic lines from the Northern Tyrrhenian Sea, Italy, indicate that major extensional displacements were accommodated along east-dipping low-angle detachment faults. The rifting and subsidence in the Northern Tyrrhenian Sea basin have followed convergence and collision of the Corso-Sardinian block and the Apulian microplate. This collisional episode produced the Northern Apennines fold-and-thrust belt. Major extensional faults cut down-section through the stratigraphy and pre-existing west-dipping thrust faults. West-dipping thrusts can also be reactivated and form antithetic faults to the east-dipping detachments. Brittle deformation conditions predominated during the extensional phase. The geometry, internal structure and the fabrics (brittle and penetrative) associated with a well-exposed low-angle extensional detachment in Elba are presented in this paper. A geometrical model for the brittle extensional faulting is presented in which regional extension was accommodated on a system consisting of two sets of simultaneously active antithetic faults. The east-dipping detachment faults appear to have started at steeper angles, based on field and seismic observations, and rotated counter-clockwise to lower dips. Due to this rotation, and for space accommodation, antithetic west-dipping faults formed and rotated clockwise. A tectonic model is proposed whereby slowing of the convergence between Apulia and Corsica, as well as Tethys oceanic crust and Apulian crust subduction, led to the delamination of the Apulian litho-spheric mantle away from the crust. Accompanying asthenospheric upwelling and intrusion at the crust—mantle interface beneath the Tyrrhenian Sea caused late orogenic crustal stretching in the Northern Apennines internal zone.

The Late Proterozoic Dokhan volcanic suite (620 Ma) of the northern Nubian shield is the product of Late Pan-African volcanism. The suite covers the entire spectrum from basalt to high-silica rhyolite and occurs as two units: a dark-coloured unit containing basalt-andesite-dacite, and a light-coloured unit encompassing dacite-rhyodacite-rhyolite. The latter unit is made up largely of ash flow tuffs and ign-imbrites that are locally interstratified with basalt and andesite lava flows. The suite forms a continuum in composition with a wide range of Si02 (48–77 wt%), CaO (0.1–8.9 wt%), Sr (81–906 ppm), Zr (85–340 ppm) as well as most other elements, and is moderately enriched in incompatible elements, including rare earth elements (REE). The suite exhibits fractionated, subparallel REE patterns that are similar overall to Andean andesites and ignimbrites. Well-defined major and trace element trends and fractionated REE profiles are consistent with a fractionated basalt to rhyolite calc-alkaline magma series. It is a typical calc-alka-line orogenic complex and exhibits mineralogical-geochemical traits of arc-related volcanism. The suite neither resembles products of extensional nor transitional tectonic regimes as previously thought, but was produced in a subduction-related tectonic environment. The mafic nature of the least-evolved rocks of the suite, along with its relatively low initial 87Sr/86Sr ratio (0.7039) are considered to indicate a mantle source. A mantle-derived basaltic magma fractionated, with amphibole and plagioclase dominating the fractionating assemblage, to produce the more felsic varieties, as suggested by major and trace element fractionation modelling.

Ninella tarimensis from the Lower Cambrian Yurtus Formation of western Xinjiang, China, is shown to be a relative of the halkieriids and siphogonuchitids. These are known principally from dispersed sclerites, presumably secreted by slug-like organisms that were an abundant component of the Cambrian benthos. The sclerites of N. tarimensis are relatively small, strongly recurved and usually possess an upper surface ornamented with transverse sculpture. The lower surface is more or less smooth and is joined to the upper surface via steep faces that may be grooved. The apertural region is quadrate in outline and bears a circular foramen. Ninella is fairly widespread and is known from elsewhere in China (Guizhou and Shaanxi Provinces) and from Kazakhstan. A brief description of the siphogonuchitid scleritome is also presented, based on dispersed sclerites and shells from the Lower Cambrian of Shaanxi Province, China. Formal synonymy of the sciotaxa Siphogonuchites, Dabashanites, Lopochites, and Maikhanella as Siphogonuchites is proposed.

By the new method of Sm—Nd isotopic dating on phosphatic small skeletal fossils and collo-phanite minerals, the Zhongyicun Member of the earliest Cambrian Meishucun Stage at Meishucun in Yunnan, southern China, has been dated at 562.8 ± 7.9 Ma and 562.1 ± 5.7 Ma. Another Sm—Nd age, 570.3 ± 17.1 Ma, has been obtained with samples from the Zhongyicun Member in Yunnan and its stratigraphic equivalents in Sichuan and Xinjiang. These data tend to suggest that the best age estimate of the Precambrian—Cambrian boundary is very likely within the range of 560–570 Ma. As biophosphates and sedimentary phosphates are widely distributed in sequences of the Precambrian—Cambrian transition, the Sm-Nd isotopic method is recommended as an effective approach for precise dating of the initial Cambrian boundary.

New geological mapping has revealed further details of the tectonic and stratigraphic effects of Devonian and later reactivations of the Billefjorden Fault Zone, one of a number of important north—south trending lineaments in Svalbard. Analysis of offsets along the many steeply-dipping faults within the zone, and effects on the subsidence and deformation of the adjacent crustal blocks, is presented as a series of tectonic maps from the Late Devonian through to the Tertiary. Late Devonian sinistral transpression, suggested previously, cannot be ruled out, and Carboniferous reactivation was dominated by extension, with possibly a slight dextral strike-slip component. After Late Carboniferous to Early Cretaceous platform subsidence, during which the fault zone had little effect on sedimentation, development of the Tertiary West Spitsbergen Fold Belt (related to the opening of the Arctic Ocean) involved compressive (and transpressive?) reactivation of basement-seated structures further east, including the Billefjorden Fault Zone. In the Billefjorden—Austfjorden area this produced a large monoclinal fold across the fault zone, which was later cross-cut by extensional structures to produce the present day Billefjorden syncline. This localized late extension is related to a slight variation in the trend of the Billefjorden Fault Zone through this area.

Seven radiocarbon dates of carbonate shells and charcoal from the upper two metres of sediment in the Indo-Gangetic plains of northern Bihar, eastern India, can be divided into three groups, with the following approximate ages: 2400±45 a BP (two samples), 1100±45 a BP (four samples) and 765±45 a BP (one sample). This evidence for at least three episodes of sedimentation in the last 2400 a contrasts with evidence of greater ages from similarly near-surface sediments in the middle Gangetic plains of Uttar Pradesh, further west. In these more westerly areas, greater ages and well-developed river terraces point to much more restricted late Holocene sedimentation. Rates of net sediment accumulation calculated using our Bihar ages, spanning a period of the order of 103–104 a, are similar to those calculated for periods of the order of 105–106 a for the Himalayan foreland basin. This suggests that, in the whole basin case, short-period rates higher than the Bihar rates have been compensated by longer than Bihar periods of non-deposition or erosion.

A macroscopic fold formed during the fourth deformation, D4, in the Robertson River Metamorphics, north Queensland, Australia. Growth of biotite, garnet, staurolite and andalusite porphyroblasts also occurred synchronous with D4. Only biotite porphyroblasts have formed preferred alignments across the fold, and they define two dominant orientations. The more common is parallel to D4 fold axes, which is also parallel to D1 D2 and D4 intersection lineations. The other varies up to 90° from this within the D4 axial plane. Mineral elongation lineations do not reflect the extension direction of the deformation in which they formed (D4), but are a function of pre-existing anisotropics in the rock parallel to intersection lin-eations. Porphyroblast growth is inferred to be a result of microfracturing along favourably oriented linear anisotropics formed by multiple intersection of foliations, as well as parting of the the S1, and S2 foliations.

Recently, an outcrop with clear evidence for Quaternary faulting has been discovered in the eastern part of Bohemian Massif, 25 km southwest of Brno (Moravia, Czech Republic). Basement serpentinite, fluvial gravels, loess and young scree are affected by a steep NNW–SSE trending fault. The geological situation of the outcrop is described for the first time in this article.

The development of a series of internationally acceptable chronostratigraphical units initially grew up through agreed use. Today's requirement of endorsement by the International Commission on Stratigraphy has resulted in the official rejection of names which are perfectly valid and still essential in the parts of the world for which they were introduced. Recognition of this fact is urged, by the acceptance of the Secondary Standards as locally defined chronostratigraphical units pending possible future correlation with the primary standard.