The structure of a small complexly‐deformed area within Ordovician rocks near Mansfield,Victoria

Two distinct groups of granitoids occur on the eastern side of the Kosciusko Batholith. Those considered to be derivatives of sedimentary source rocks (S‐types) are usually foliated and either contain cordierite or white‐mica secondary after cordierite. The granitoids produced from igneous source material (I‐types) are generally massive and frequently contain hornblende. Geochemical parameters provide the best discriminant between the two groups, I‐types have higher Ca, Al, Na₂O/K₂O, and Fe₂O₃/FeO, and lower Fe, Mg, Sc, V, Cr, Co, Ni, Cu, Zn, Ba, Rb, Th, La, Ce, and Y than S‐types of comparable SiO₂ values.

The differences between the two groups are not the result of differences in the melt‐forming process but reflect differences in the nature of the source material. Thus the geochemical features of the S‐type granitoids are indicative of their source rocks having been through a process of chemical weathering in a sedimentary cycle. Conversely, the I‐type granitoids were derived from fractionated rocks that had not been involved in weathering processes.     

The role of sea ice formation in cycling of aluminium in northern Marguerite Bay,Antarctica

The use of dissolved Al as a tracer for oceanic water masses and atmospheric dust deposition of biologically important elements, such as iron, requires the quantitative assessment of its sources and sinks in seawater. Here, we address the relative importance of oceanic versus atmospheric inputs of Al, and the relationship with nutrient cycling, in a region of high biological productivity in coastal Antarctica. We investigate the concentrations of dissolved Al in seawater, sea ice, meteoric water and sediments collected from northern Marguerite Bay, off the West Antarctic Peninsula, from 2005 to 2006. Dissolved Al concentrations at 15 m water depth varied between 2 and 27 nM, showing a peak between two phytoplankton blooms. We find that, in this coastal setting, upwelling and incorporation of waters from below the surface mixed layer are responsible for this peak in dissolved Al as well as renewal of nutrients. This means that changes in the intensity and frequency of upwelling events may result in changes in biological production and carbon uptake. The waters below the mixed layer are most likely enriched in Al as a result of sea ice formation, either causing the injection of Al-rich brines or the resuspension of sediments and entrainment of pore fluids by brine cascades. Glacial, snow and sea ice melt contribute secondarily to the supply of Al to surface waters. Total particulate Al ranges from 93 to 2057 mg/g, and increases with meteoric water input towards the end of the summer, indicating glacial runoff is an important source of particulate Al. The (Al/Si)_opal of sediment core top material is considerably higher than water column opal collected by sediment traps, indicative of a diagenetic overprint and incorporation of Al at the sediment–water interface. Opal that remains buried in the sediment could represent a significant sink of Al from seawater.     

Subject Index

Subject Index

Subject Index     

A mantle plume origin for the Siberian traps: uplift and extension in the West Siberian Basin, Russia

The West Siberian Basin (WSB) records a detailed history of Permo-Triassic rifting, extension and volcanism, followed by Mesozoic and Cenozoic sedimentation in a thermally subsiding basin. Sedimentary deposits of Permian age are absent from much of the basin, suggesting that large areas of the nascent basin were elevated and exposed at that time. Industrial seismic and well log data from the basin have enabled extension and subsidence modelling of parts of the basin. Crustal extension (β) factors are calculated to be in excess of 1.6 in the northern part of the basin across the deep Urengoy graben. 1-D backstripping of the Triassic to Cenozoic sedimentary sequences in this region indicates a period of delayed subsidence during the early Mesozoic. The combination of elevation, rifting and volcanism is consistent with sublithospheric support, such as a hot mantle plume.

This interpretation accords with the geochemical data for basalts from the Siberian Traps and the West Siberian Basin, which are considered to be part of the same large igneous province. Whilst early suites from Noril'sk indicate moderate pressures of melting (mostly within the garnet stability field), later suites (and those from the West Siberian Basin) indicate shallow average depths of melting. The main region of magma production was therefore beneath the relatively thin (ca. 50–100 km) lithosphere of the basin, and not the craton on which the present-day exposure of the Traps occurs. The indicated uplift, widespread occurrence of basalts, and short duration of the volcanic province as a whole are entirely consistent with published models involving a mantle plume. The main argument against the plume model, namely lack of any associated uplift, appears to be untenable.     

Some observations on the kinetics of nitrifying activated-sludge plants

Conclusions Further basic information on the types and properties of the microorganisms which inhabit activated-sludge plants is required before it will be possible to give a detailed account of the fundamental kinetics of the process. However, in the case of certain organisms, such as the nitrifying bacteria, which have highly characteristic properties easily recognized by the chemical changes which they produce, it is possible to define the conditions necessary to retain these organisms in the system, apparently with sufficient accuracy for most practical purposes. It is found that to achieve nitrification consistently, the period of aeration must exceed a minimum value which is a function of the concentration of activated sludge, the temperature, and the strength of the sewage. When conditions are favourable for nitrification, the rate of nitrification and the rate of consumption of oxygen due to this process will tend to an equilibrium level which is proportional to the concentration of activated sludge under aeration. In an aeration unit through which the liquid travels with ideal piston-flow, the concentration of ammonia in the effluent under the above conditions will be normally very small. The effect of longitudinal mixing will be to increase slightly the concentration of ammonia in the effluent.

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Schlussfolgerungen Weitere Kenntnisse betreffend die Typen und die Eigenschaften der Mikroorganismen, die man in Belebtschlammanlagen findet, sind erforderlich, ehe es m?glich sein wird, im einzelnen Rechenschaft über die Grunds?tze der Kinetik dieses Verfahrens zu geben. Im Falle gewisser Organismen jedoch-wie z.B. der nitrierenden Bakterien, welche ausgesprochen charakteristische Eigenschaften haben, die leicht an den chemischen Ver?nderungen, die sie hervorrufen, zu erkennen sind-, ist es m?glich, die zur Erhaltung dieser Organismen in der Anlage n?tigen Bedingungen anscheinend mit genügender Genauigkeit für die meisten praktischen Zwecke festzulegen. Es wurde festgestellt, dass-wenn eine best?ndige Nitrifikation stattfinden soll-die Belüftungszeit einen minimalen Wert überschreiten muss, der eine Funktion der Konzentration des Belebtschlamms, der Temperatur und der Beschaffenheit der Abw?sser ist. Wenn die Bedingungen für die Nitrifikation günstig sind, werden der Grad der Nitrifikation und der Grad des Sauerstoffverbrauches, die von diesem Prozess abh?ngen, dahin streben, ein Gleichgewicht zu erreichen, welches zur Konzentration des belüfteten Belebtschlamms proportional ist. In einer Belüftungeinheit, durch welche die Flüssigkeit in idealer stossartiger Str?mung fliesst, ist die Konzentration von Ammoniak im Abfluss unter den obenerw?hnten Bedingungen normalerweise sehr klein. Die L?ngsmischung hat zur Folge, dass die Konzentration von Ammoniak im Abfluss leicht ansteigt.

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Conclusions Il faut obtenir d'autres renseignements essentiels sur les types de micro-organismes vivant dans les installations de boue activée et sur leurs propriétés avant de pouvoir donner un exposé détaillé sur la cinétique fondamentale du processus. Toutefois, dans le cas de certains organismes, notamment pour les bactéries nitrifiantes, qui présentent des propriétés très caractéristiques facilement reconnaissables par les modifications chimiques qu'elles produisent, il est possible de définir les conditions nécessaires pour maintenir ces organismes dans les installations, et ceci avec une exactitude suffisante à toutes fins pratiques. On a trouvé que, pour obtenir une nitrification uniforme, la période d'aération doit dépasser une valeur minimum qui est fonction de la concentration de la boue activée, de la température et de la charge des eaux usées. Lorsque les conditions sont favorables à la nitrification, le degré de la nitrification et le taux de consommation d'oxygène dus à ce processus tendent vers un niveau d'équilibre qui est proportionnel à la concentration de la boue activée soumise à l'aération. Dans une unité d'aération à travers laquelle la boue passe selon un débit idéal type piston, la concentration d'ammonium dans l'effluent, dans les conditions mentionnées ci-dessus, sera normalement minime. L'effet du mélange longitudinal augmentera quelque peu la concentration d'ammonium dans l'effluent.

     

Herschel SPIRE fourier transform spectrometer: calibration of its bright-source mode

The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two detector setting modes: (a) a nominal mode, which is optimized for observing moderately bright to faint astronomical targets, and (b) a bright-source mode recommended for sources significantly brighter than 500 Jy, within the SPIRE FTS bandwidth of 446.7–1544 GHz (or 194–671 microns in wavelength), which employs a reduced detector responsivity and out-of-phase analog signal amplifier/demodulator. We address in detail the calibration issues unique to the bright-source mode, describe the integration of the bright-mode data processing into the existing pipeline for the nominal mode, and show that the flux calibration accuracy of the bright-source mode is generally within 2 % of that of the nominal mode, and that the bright-source mode is 3 to 4 times less sensitive than the nominal mode.     

Herschel SPIRE FTS spectral mapping calibration

The Herschel SPIRE Fourier transform spectrometer (FTS) performs spectral imaging in the 447–1546 GHz band. It can observe in three spatial sampling modes: sparse mode, with a single pointing on sky, or intermediate or full modes with 1 and 1/2 beam spacing, respectively. In this paper, we investigate the uncertainty and repeatability for fully sampled FTS mapping observations. The repeatability is characterised using nine observations of the Orion Bar. Metrics are derived based on the ratio of the measured intensity in each observation compared to that in the combined spectral cube from all observations. The mean relative deviation is determined to be within 2 %, and the pixel-by-pixel scatter is ～ 7 %. The scatter increases towards the edges of the maps. The uncertainty in the frequency scale is also studied, and the spread in the line centre velocity across the maps is found to be ～ 15 km s ^{? 1}. Other causes of uncertainty are also discussed including the effect of pointing and the additive uncertainty in the continuum.     

A Search for CO J = 2 → 1 Emission from the Metal Rich Globular Cluster NGC 6356

We have observed the metal-rich globular cluster NGC 6356 in the CO J = 2 → 1 transition. The data revealed no apparent emission corresponding to the radial velocity of the cluster and we present an upper limit to the mass of gas in the cluster core. This revised version was published online in September 2006 with corrections to the Cover Date.     

Spatial distribution of micrometre‐scale porosity and permeability across the damage zone of a reverse‐reactivated normal fault in a tight sandstone: Insights from the Otway Basin,SE Australia

Knowledge of the permeability structure of fault‐bearing reservoir rocks is fundamental for developing robust hydrocarbon exploration and fluid monitoring strategies. Studies often describe the permeability structure of low porosity host rocks that have experienced simple tectonic histories, while investigations of the influence of faults with multiple‐slip histories on the permeability structure of porous clastic rocks are limited. We present results from an integrated petrophysical, microstructural, and mineralogical investigation of the Eumeralla Formation (a tight volcanogenic sandstone) within the hanging wall of the Castle Cove Fault which strikes 30 km NE–SW in the Otway Basin, southeast Australia. This late Jurassic to Cenozoic‐age basin has experienced multiple phases of extension and compression. Core plugs and thin sections oriented relative to the fault plane were sampled from the hanging wall at distances of up to 225 m from the Castle Cove Fault plane. As the fault plane is approached, connected porosities increase by ca. 10% (17% at 225 m to 24% at 0.5 m) and permeabilities increase by two orders of magnitude (from 0.04 mD at 225 m to 1.26 mD at 0.5 m). Backscattered Scanning Electron Microscope analysis shows that microstructural changes due to faulting have enhanced the micrometre‐scale permeability structure of the Eumeralla Formation. These microstructural changes have been attributed to the formation of microfractures and destruction of original pore‐lining chlorite morphology as a result of fault deformation. Complex deformation, that is, formation of macrofractures, variably oriented microfractures, and a hanging wall anticline, associated with normal faulting and subsequent reverse faulting, has significantly influenced the off‐fault fluid flow properties of the protolith. However, despite enhancement of the host rock permeability structure, the Eumeralla Formation at Castle Cove is still considered a tight sandstone. Our study shows that high‐resolution integrated analyses of the host rock are critical for describing the micrometre‐scale permeability structure of reservoir rocks with high porosities, low permeabilities, and abundant clays that have experienced complex deformation.