The inception and early evolution of the North Alpine Foreland Basin, Switzerland

The stratigraphy of the Eocene-Miocene peripheral foreland basin in Switzerland consists of basal deposits of Nummulitic Limestones and Globigerina Marls representing a phase of deepening, followed by two shallowing-up megacycles culminating in fully continental sedimentation. The onset of sedimentation was diachronous and took place on an unconformity surface with increasing stratigraphic gap to the north and west. In the Ultrahelvetic units, which were derived from the south and have a provenance between the Helvetic shelf and the Penninic ocean, the stratigraphic gap is minimal. This restricts the initiation of erosion of the southern European margin due to emersion to post-Maastrichtian and pre-late Palaeocene. This coincides with the final closing of the Valais trough and may therefore be interpreted as the point at which continental flexure s. s. started. In the autochthon, the subcrop map of the unconformity surface shows that the regional pattern of subcropping units is oblique to both neo-Alpine tectonic structures and Helvetic (Mesozoic) passive margin structures. There are local zones of disruption to the broad regional pattern suggesting that the basal unconformity was corrugated. Both the paliaspastic restoration of the autochthon relative to the thrust front during the Palaeocene, and the regional pattern of erosion indicate that the basal unconformity may be due to erosion of a flexural forebulge. Following deposition of the shallow water Nummulitic Limestones and the deeper water Globigerina Marls, clastic sediments were shed from the orogenic wedge in the south. These turbidites, the Taveyannaz Sandstones, filled both ponded basins at the contemporaneous thrust front and the frontal trench or foredeep. Evidently, early thrusts drove at a shallow level into the embryonic basin as ‘front-runners’, whereas most shortening and uplift continued to take place within the main part of the orogenic wedge further to the south. Eventually, the frontal palaeohighs, together with the turbidite basins, were buried by the northward emplacement of surface mud-slides, and sediment depocentres were translated northwards onto the foreland. The most likely cause of the underfilled ‘Flysch’ stage is the rapid advance of a submarine thrust wedge over the flexed European plate which resulted in (i) low sediment fluxes and (ii) high subsidence rates associated with the rapid migration of the load and depocentre. Later, as the rate of advance slowed and the wedge became subaerially exposed, the basin rapidly filled with coarse-grained detritus representing the ‘Molasse’ stage.     

Application of statistical approaches to analyze geological,geotechnical and hydrogeological data at a fractured-rock mine site in Northern Canada

Mine site characterization often results in the acquisition of geological, geotechnical and hydrogeological data sets that are used in the mine design process but are rarely co-evaluated. For a study site in northern Canada, bivariate and multivariate (hierarchical) statistical techniques are used to evaluate empirical hydraulic conductivity estimation methods based on traditional rock mass characterisation schemes, as well as to assess the regional hydrogeological conceptual model. Bivariate techniques demonstrate that standard geotechnical measures of fracturing are poor indicators of the hydraulic potential of a rock mass at the study site. Additionally, rock-mass-permeability schemes which rely on these measures are shown to be poor predictors of hydraulic conductivity in untested areas. Multivariate techniques employing hierarchical cluster analysis of both geotechnical and geological data sets are able to identify general trends in the data. Specifically, the geological cluster analysis demonstrated spatial relationship between intrusive contacts and increased hydraulic conductivity. This suggests promise in the use of clustering methods in identifying new trends during the early stages of hydrogeological characterization.     

The Millennium Galaxy Catalogue: bulge–disc decomposition of 10 095 nearby galaxies

We present near-infrared (NIR) adaptive optics-assisted spectroscopic observations of the  CO (Δμ= 2)  absorption bands towards the centre of the giant elliptical galaxy NGC 1399. The observations were made with NAOS-CONICA (on the European Southern Observatory's Very Large Telescope) and have a full width at half-maximum resolution of 0.15 arcsec (14 pc). Kinematic analysis of the observations reveals a decoupled core and strongly non-Gaussian line-of-sight velocity profiles in the central 0.2 arcsec (19 pc). NIR imaging also indicates an asymmetric elongation of the central isophotes in the same region.
We use spherical orbit-superposition models to interpret the kinematics, using a set of orthogonal 'eigen-velocity profiles' that allow us to fit models directly to spectra. The models require a central black hole of mass  1.2^+0.5_−0.6× 10⁹ M_⊙  , with a strongly tangentially biased orbit distribution in the inner 40 pc.     

Infrared studies of the lunar terrain

Observations have been made of the unlit limb of the Moon at infrared wavelengths, and detailed apparent temperature charts for the entire limb are presented. A number of thermal anomalies lying close to the limb have been discovered. Evidence is presented that there are sufficient large boulders near the lunar limb to invalidate temperatures determined at a single infrared wavelength during the night or at eclipse. The possibility that thermal anomalies are produced by local variations in the area density of boulders is discussed.     

The relationship between cooling flows and metallicity measurements for X-ray-luminous clusters

We explore the relationship between the metallicity of the intracluster gas in clusters of galaxies, determined by X-ray spectroscopy, and the presence of cooling flows. Using ASCA spectra and ROSAT images, we demonstrate a clear segregation between the metallicities of clusters with and without cooling flows. On average, cooling-flow clusters have an emission-weighted metallicity a factor ∼ 1.8 times higher than that of non-cooling-flow systems. We suggest that this is caused by the presence of metallicity gradients in the cooling-flow clusters, coupled with the sharply peaked X-ray surface brightness profiles of these systems. Non-cooling-flow clusters have much flatter X-ray surface brightness distributions and are thought to have undergone recent merger events, which may have mixed the central high-metallicity gas with the surrounding less metal-rich material. We find no evidence for evolution in the emission-weighted metallicities of clusters within z  ∼ 0.3.     

Experimental investigation on a two-part underwater towed system

An experimental set-up is developed and proved to be effective for laboratory study of an underwater towed system. The experimental technique gives a practical method for monitoring the kinematic and dynamic performance of an underwater towed system in a ship towing tank. Both the theoretical and experimental results in the investigation indicate that the hydrodynamic response of a towed vehicle to the wave induced motion of a towing ship can be significantly reduced by applying a two-part tow method. A comparison of the numerical and experimental results in the investigation demonstrates that the numerical simulation results are close to the experimental data, overall agreement between experimental and theoretical results is satisfactory. The results qualitatively verify the mathematical model of a two-part underwater towed system proposed by Wu and Chwang [Wu, J., Chwang, A.T., 2000. A hydrodynamic model of a two-part underwater towed system. Ocean Engineering 27 (5), 455–472].     

Observations of the birth of a small coronal hole

Using soft X-ray data from the S-054 X-ray spectrographic telescope aboard Skylab, we observed temporal changes in the emission structure of the X-ray corona associated with the birth of a small coronal hole. Designated as CH6, this coronal hole was born near the equator in a time interval less than 9 1/2 hr. By constructing a light curve for a point near the center of CH6, we observed a sudden 40% decrease in X-ray emission associated with the birth of this coronal hole. On a time scale of hours, the growth of CH6 in area proceeded faster than the average rate predicted by the diffusion of solar fields. The short term decay of CH6 followed the diffusive rate to within experimental uncertainty, On a time scale of one rotation, the subsequent development of CH6 was not consistent with steady growth at the average rate predicted by diffusion.Skylab Solar Workshop Post-Doctoral Appointee, 1975–1977. The Skylab Solar Workshops are sponsored by NASA and NSF and managed by the High Altitude Observatory, National Center for Atmospheric Research.     

Infrared studies of the lunar terrain

This paper presents an infrared study of thermal anomalies during the lunar night. From observations of the most intense anomalies at several wavelengths it is deduced that fields of boulders are responsible for the thermal enhancement; the cooling curves of the remainder are consistent with such a model. High resolution Lunar Orbiter photographs of some of the thermal anomalies reveal boulders to be present within them in just the right numbers. The ages and distribution of thermal anomalies are discussed in the light of this model.     

An 40Ar/39Ar study of a polymetamorphic complex in the Arunta Block,Central Australia

A polymetamorphic complex in the Arunta Block, Central Australia, which has undergone metasomatism involving introduction of Rb and loss of Sr has been investigated by ⁴⁰Ar/ ³⁹Ar step and total-degassing techniques in an attempt to date five metamorphic events (M1–M5) identified microstructurally. The complex isotopic data and apparent age spectra obtained have been interpreted in the light of constraints provided by an associated tectonometamorphic study, together with independent geochronological controls from the immediate study area and elsewhere in the Arunta Block. This has led to the delineation of ages of 1,780–1,820 M.y. for M1, 1,690–1,720 M.y. for M2, 1,450–1,500 M.y. for M3, 1,030–1,060 M.y. for M4 and 370–510 for M5. The polyphase M5 event is correlated with the Alice Springs Orogeny, previously accorded younger age limits of 330–370 M.y. The latter are interpreted to reflect closure of mica K/Ar systems as uplift continued subsequent to the close of the event, possibly culminating in minor high-level brittle deformation and the development of pseudotachylytes in the study area.Apparent age spectra recorded in this study do not all conform with generally accepted patterns of behaviour of mineral systems which have undergone polythermal histories. Two hornblendes have survived subsequent high temperature metasomatic reheating without loss of argon or resetting of their ages. Their resistance to argon loss may be attributable to low water contents, due to their growth under anhydrous granulite facies conditions, and may reflect a relationship between argon loss from hornblende and the water content of hornblende, which decreases with increasing metamorphic grade (Kostyuk and Sobolev 1969). Other samples display false plateaux in their apparent age spectra and in three cases the spectra are indistinguishable from those of undisturbed spectra.The age data recorded in this study suggest that during basement reactivation loss of argon is mainly confined to the vicinity of shear zones, implying that diffusion of argon from minerals in the deep crust may be dependent more on deformation than on reheating. However, thermal activity may also be associated with active shear zones, through the medium of superheated fluids streaming up the shear zones from below. The wide spread of K/Ar and ⁴⁰Ar/³⁹Ar ages (330–510 M.y.), recorded for the Alice Springs Orogeny in the Arunta basement, may reflect such controls.