The Tajik Basin: A composite record of sedimentary basin evolution in response to tectonics in the Pamir

Investigation of a >6-km-thick succession of Cretaceous to Cenozoic sedimentary rocks in the Tajik Basin reveals that this depocentre consists of three stacked basin systems that are interpreted to reflect different mechanisms of subsidence associated with tectonics in the Pamir Mountains: a Lower to mid-Cretaceous succession, an Upper Cretaceous–Lower Eocene succession and an Eocene–Neogene succession. The Lower to mid-Cretaceous succession consists of fluvial deposits that were primarily derived from the Triassic Karakul–Mazar subduction–accretion complex in the northern Pamir. This succession is characterized by a convex-up (accelerating) subsidence curve, thickens towards the Pamir and is interpreted as a retroarc foreland basin system associated with northward subduction of Tethyan oceanic lithosphere. The Upper Cretaceous to early Eocene succession consists of fine-grained, marginal marine and sabkha deposits. The succession is characterized by a concave-up subsidence curve. Regionally extensive limestone beds in the succession are consistent with late stage thermal relaxation and relative sea-level rise following lithospheric extension, potentially in response to Tethyan slab rollback/foundering. The Upper Cretaceous–early Eocene succession is capped by a middle Eocene to early Oligocene (ca. 50–30 Ma) disconformity, which is interpreted to record the passage of a flexural forebulge. The disconformity is represented by a depositional hiatus, which is 10–30 Myr younger than estimates for the initiation of India–Asia collision and overlaps in age with the start of prograde metamorphism recorded in the Pamir gneiss domes. Overlying the disconformity, a >4-km-thick upper Eocene–Neogene succession displays a classic, coarsening upward unroofing sequence characterized by accelerating subsidence, which is interpreted as a retro-foreland basin associated with crustal thickening of the Pamir during India–Asia collision. Thus, the Tajik Basin provides an example of a long-lived composite basin in a retrowedge position that displays a sensitivity to plate margin processes. Subsidence, sediment accumulation and basin-forming mechanisms are influenced by subduction dynamics, including periods of slab-shallowing and retreat.     

Benthic fluxes of copper,complexing ligands and thiol compounds in shallow lagoon waters

Benthic fluxes of copper, copper complexing ligands and thiol compounds in the shallow waters of Venice Lagoon (Italy) were determined using benthic chambers and compared to porewater concentrations to confirm their origin. Benthic copper fluxes were small due to small concentration differences between the porewaters and the overlying water, and the equilibrium concentration was the same at both sites, suggesting that the sediments acted to buffer the copper concentration. Thiol fluxes were ～10 × greater at 50–60 pmol cm^?2 h^?1, at the two sites. Porewater measurements demonstrated that the sediments were an important source of the thiols to the overlying waters. The overlying waters were found to contain at least two ligands, a strong one, L1 (log K′_CuL1 = 14.2) and a weaker one, L2 (log K′_CuL2 = 12.5). The concentration of L1 remained relatively constant during the incubation and similar to that of copper, whereas that of L2 was in great excess of copper, its concentration balanced by porewater releases and breakdown, probably due to uptake by microorganisms, similar to that of the thiol compounds. Similarity of the thiol and L2 concentrations and similar complex stability with copper suggest that L2 was dominated by the thiols. The free copper concentration ([Cu´]) in the Lagoon waters was lowered by a factor of 10⁵ as a result of the organic complexation.     

Formation Flying for a Fresnel Lens Observatory Mission

The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond (μ^′′) angular resolution [1]. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and the associated detector are carried on two spacecraft separated by up to 10⁶ km. These studies were performed at the NASA Goddard Space Flight Center Integrated Mission Design Center (IMDC) which developed spacecraft, orbital dynamics, and mission profiles. The results of the studies indicated that the missions are challenging but could be accomplished with technologies available currently or in the near term. The findings of the original studies have been updated taking account of recent advances in ion thruster propulsion technology.     

A note on the use of two-layer models of coastally trapped waves

Several aspects of coastally trapped wave behavior in two-layer models and in continuously stratified models are considered. A two-layer model and a uniformly stratified model are compared over a step shelf showing that, although they predict qualitatively different free-wave dispersion properties, some features of their long wave behavior are qualitatively similar. A sharp pycnocline model (a continuously stratified approximation to the two-layer model) is used to show that the presence of a vertical coastal wall (required in most two-layer models) produces substantial changes in the free-wave behavior. With a vertical coastal wall, baroclinic motions may be trapped close to the coast when the bottom there appears locally flat. Without a vertical coastal wall, such near-cost trapping apparently does not occur and the lowest mode of the sharp pycnocline model behaves more like the lowest mode of a uniformly stratified model.     

Impacts of climate variability on stream-flow in the Yellow River

This paper examines the impacts of climate variability upon the regional hydrological regimes of the Yellow River in China. Results indicate that the average annual precipitation is 494·8 mm in La Niña years and only 408·8 mm in El Niño years. The difference is 86·0 mm, or 18·8% over the long-term average. The stream-flows in the La Niña years are higher than that in El Niño years: 9·2% at the Lan-Zhou station, 9·5% for Tou-Dao-Guai station, 11·8% for Long-Men, 17·6% for San-Men-Xia, 19·2% at the Hua-Yuan-Hou station, and 22·0% at the Li-Jin station. Both precipitation and stream-flow responses show temporal and spatial patterns. The relationship among the stream-flow, precipitation, and temperature, which was obtained by ArcGIS Geostatistical Analyst based on observed data, indicates stream-flow is sensitive to both precipitation and temperature. For small precipitation increases (less than 13%), the stream-flow percentage change is less than the precipitation change for the Yellow River. The results of this paper can be used as a reference for watershed water resources planning and management to maintain the healthy life and proper function of the river. Copyright © 2007 John Wiley & Sons, Ltd.     

The anomalous properties of Markarian 1460

We present and discuss optical, near-infrared and H  i measurements of the galaxy Markarian 1460 at a distance of 19 Mpc in the Ursa Major Cluster. This low-luminosity ( M _B =−14) galaxy is unusual because (i) it is blue ( B − R =0.8) and has the spectrum of an H  ii galaxy, (ii) it has a light profile that is smooth and well fitted by an r ^1/4 and not an exponential function at all radii larger than the seeing, and (iii) it has an observed central brightness of about μ _B =20 mag arcsec⁻² , intermediate between those of elliptical galaxies (on the bright μ _B side) and normal low-luminosity dwarf irregular (on the low μ _B side) galaxies. No other known galaxy exhibits all these properties in conjunction. On morphological grounds this galaxy looks like a normal distant luminous elliptical galaxy, since the Fundamental Plane tells us that higher luminosity normal elliptical galaxies tend to have lower surface-brightnesses. Markarian 1460 has 2×10⁷ M_⊙ of H  i and a ratio M (H  i )/ L _B of 0.2, which is low compared to the typical values for star-forming dwarf galaxies. From the high surface-brightness and r ^1/4 profile, we infer that the baryonic component of Markarian 1460 has become self-gravitating through dissipative processes. From the colours, radio continuum, H  i and optical emission line properties, and yet smooth texture, we infer that Markarian 1460 has had significant star formation as recently as ∼1 Gyr ago but not today.     

On the lack of cold dust in IRAS P09104+4109 and IRAS F15307+3252: their spectral energy distributions and implications for finding dusty AGNs at high redshift

We present upper limits on the 850-μm and 450-μm fluxes of the warm hyperluminous (bolometric luminosity     galaxies IRAS P09104+4109     and IRAS F15307+3252     , derived from measurements using the SCUBA bolometer array on the James Clerk Maxwell Telescope. Hot luminous infrared sources like these are thought to differ from more normal cold ultraluminous infrared     galaxies in that they derive most of their bolometric luminosities from dusty active galactic nuclei (AGNs) as opposed to starbursts. Such hot, dusty AGNs at high redshift are thought to be responsible for much of the mass accretion of the Universe that is in turn responsible for the formation of the supermassive black holes seen in the centres of local galaxies. The galaxy IRAS P09104+4109 is also unusual in that it is a cD galaxy in the centre of a substantial cooling-flow cluster, not an isolated interacting galaxy like most ultraluminous infrared galaxies. Previously it was known to have large amounts of hot     dust from IRAS observations. We now show that the contribution of cold dust to the bolometric luminosity is less than 3 per cent. Most ultraluminous infrared galaxies possess large amounts of cold dust, and it is now known that some cooling-flow cluster cD galaxies do as well. Yet this object, which is an extreme example of both, does not have enough cold gas to contribute significantly to the bolometric luminosity. We outline physical reasons why this could have happened. We then provide a discussion of strategies for finding hot dusty AGNs, given the limitations on submillimetre surveys implied by this work.     

Simple spatially-distributed models for predicting flood inundation: A review

In this paper we review recent progress in the use of reduced complexity models for predicting floodplain inundation. We review the theoretical basis for modelling floodplain flow with simplified hydraulic treatments based on a dimensional analysis of the one-dimensional shallow water equations. We then review how such schemes can be applied in practice and consider issues of space discretization, time discretization and model parameterisation, before going on to consider model assessment procedures. We show that a key advantage of reduced complexity codes is that they force modellers to think about the minimum process representation necessary to predict particular quantities and act as a check on any tendency to reductionism. At the same time, however, the use (compared to standard hydraulic codes) of strong simplifying assumptions requires us to also address the question “how simple can a model be and still be physically realistic?” We show that by making explicit this debate about acceptable levels of abstraction, reduced complexity codes allow progress to be made in addressing a number of long-standing debates in hydraulics.     

Making space for unruly water: Sustainable drainage systems and the disciplining of surface runoff

This paper explores the disciplining of non-human actors through the example of sustainable drainage systems (SuDS) managing surface water runoff. The lens of performativity is used to examine the move from pre-modern repressive forms of discipline, to mechanisms which attempt a more productive disciplinary engagement by finding space to reform water’s more unruly behaviours. After examining the problems with traditional disciplinary approaches to water of rapid transit and exile, the paper explores the implications of a move towards SuDS technology. This change is examined using a case study of Glasgow, Scotland, where there is an attempt to utilise less repressive disciplinary mechanisms and to find spaces in the city for surface water outside the hard drainage infrastructure. New approaches to the disciplining of urban water are conceptualised as being a performance of tension between water and those who would modify its behaviour.