Crustal evolution of the Saykhandulaan inlier, Mongolia : implications for Palaeozoic arc magmatism, polyphase deformation and terrane accretion in the southeast Gobi mineral belt

The Saykhandulaan Inlier in South East Mongolia lies within the Central Asian Orogenic Belt (CAOB), and records a complex history of Palaeozoic tectonism and magmatism associated with terrane accretion on the northern margin of the Palaeo-Asian ocean. The inlier spans the boundary between the Gobi Altai back-arc basin terrane in the north and the Mandalovoo and Gurvansayhan island-arc terranes in the south which are notable for their many mineralised intrusions, including the Oyu Tolgoi gold-rich copper porphyry deposit. Results from cross-strike transects within the Saykhandulaan Inlier reveal that it can be subdivided into five parallel east–west striking litho-tectonic domains; (1) the Northern Slate Belt, comprising Devonian greenschist grade pelites and psammites with deep-marine to coastal siliciclastic protoliths; (2) the Saykhandulaan Valley Lineament Zone (SVLZ), a tectonised zone of faulted and lithologically altered volcanic rocks; (3) the High Strain Belt, consisting of tightly folded and flattened metamorphosed clastic sedimentary rocks; (4) the Molasse Succession, consisting of relatively undeformed coarse conglomerates and sandstones and, (5) the Oyut Ulaan Volcanic Group, a nearly 5 km-thick folded Carboniferous volcanic succession that hosts the mid-Carboniferous Oyut Ulaan mineralised granite. The Northern Slate Belt metasedimentary rocks record a northerly cratonic provenance, whereas all rocks to the south of the SVLZ have arc affinities. The SVLZ is thus interpreted to be the boundary between the Gobi Altai and Mandalovoo terranes. Two major deformation events are documented; (1) back-arc basin closure and inversion involving regional scale folding and greenschist grade metamorphism in the Northern Slate and High Strain Belts; (2) contraction associated with Mandalovoo terrane accretion and final closure of the Palaeo-Asian Ocean to the south. Following terrane accretion and cessation of subduction, crustal extension and strike-slip faulting further modified the crustal architecture of the inlier. The results presented here provide a useful framework for understanding the crustal evolution of adjacent regions within the southeast Gobi mineral belt

An FTIR spectrometer for remote measurements of atmospheric composition

The JPL IV interferometer, and infrared Michelson interferometer, was built specifically for recording high resolution solar absorption spectra from remote ground-based sites, aircraft and from stratospheric balloons. The instrument is double-passed, with one fixed and one moving corner reflector, allowing up to 200-cm of optical path difference (corresponding to an unapodised spectral resolution of 0.003/cm). The carriage which holds the moving reflector is driven by a flexible nut riding on a lead screw. This arrangement, together with the double-passed optical scheme, makes the instrument resistant to the effects of mechanical distortion and shock. The spectral range of the instrument is covered by two liquid nitrogen-cooled detectors: an InSb photodiode is used for the shorter wavelengths (1.85 to 5.5 microns, 1,800 to 5,500/cm) and a HgCdTe photoconductor for the range (5.5 to 15 microns, 650 to 1,800/cm). For a single spectrum of 0.01/cm resolution, which requires a scan time of 105 seconds, the signal/noise ratio is typically 800:1 over the entire wavelength range

Faecal pathogen flows and their public health risks in urban environments: A proposed approach to inform sanitation planning

© 2018 by the author. Licensee MDPI, Basel, Switzerland. Public health benefits are often a key political driver of urban sanitation investment in developing countries, however, pathogen flows are rarely taken systematically into account in sanitation investment choices. While several tools and approaches on sanitation and health risks have recently been developed, this research identified gaps in their ability to predict faecal pathogen flows, to relate exposure risks to the existing sanitation services, and to compare expected impacts of improvements. This paper outlines a conceptual approach that links faecal waste discharge patterns with potential pathogen exposure pathways to quantitatively compare urban sanitation improvement options. An illustrative application of the approach is presented, using a spreadsheet-based model to compare the relative effect on disability-adjusted life years of six sanitation improvement options for a hypothetical urban situation. The approach includes consideration of the persistence or removal of different pathogen classes in different environments; recognition of multiple interconnected sludge and effluent pathways, and of multiple potential sites for exposure; and use of quantitative microbial risk assessment to support prediction of relative health risks for each option. This research provides a step forward in applying current knowledge to better consider public health, alongside environmental and other objectives, in urban sanitation decision making. Further empirical research in specific locations is now required to refine the approach and address data gaps

Can Ocean Thermal Energy Conversion and Seawater Utilisation Assist Small Island Developing States? A Case Study of Kiribati, Pacific Islands Region

The deployment of a land-based Ocean Thermal Energy Conversion (OTEC) plant in South Tarawa, Kiribati, Pacific Islands Region, in 2020/2021, represents a major technical achievement, alongside an international development opportunity. Pacific Small Island Developing States (PSIDS) are archipelago nations with small land areas and large oceanic exclusive economic zones. Geographical isolation and large transport distances make economic development a challenge. A lack of affordable and reliable energy in many PSIDS is a development inhibitor. PSIDS are situated within the areas of highest ocean thermal potential in the world. Temperature differences between surface and 1 km depth waters, are in excess of 24°C. Regional geology and tectonics allow access to deeper, colder, waters within few kilometres of many shorelines, and close to market. Seawater Utilization technologies can catalyse varied industrial development (e.g., fresh water/aquaculture/agriculture/mineral salts). The KRISO (Korean Research Institute of Ships and Ocean Engineering)-Government of Kiribati OTEC partnership is already 7 years old (2013–2020) and has involved extensive negotiations, awareness raising programmes, and inclusive collaboration. The project will test OTEC technologies and explore a range development opportunities for Kiribati. The programme could become a role model for the application of the concept of ‘Interconnected Geoscience’

Why Disaster Subcultures Matter: A Tale of Two Communities: How and Why the 2007 Western Solomon Islands Tsunami Disaster Led to Different Outcomes for Two Ghizo Communities

At 07:45 a.m. on 2 April 2007, a tsunami hit Ghizo Island, western Solomon Islands in the south-west Pacific. Thirty-three people died on Ghizo, of whom 31 originated from a relatively small migrant Gilbertese community (transmigrated in the 1950s–1970s from Kiribati), while only two were from the majority Melanesian community. This paper documents an extensive 4-year study that addresses the potential core reasons for this asymmetrical casual impact. Community-participatory social science research was undertaken in two Gilbertese villages and two Melanesian villages. The four villages had similar spatial vulnerabilities due to their coastal location, although they had variable access to the safer higher ground. Gilbertese villages had less diverse ocean-reliant livelihoods, a limited knowledge of hinterland bush resource utilisation, uncertainties regarding land rights, and perceived ethnic discrimination. Melanesian villages had strong wantok and kastom social reciprocity cultures, a diverse set of livelihoods, wider social capital with other Melanesian communities, and greater security regarding land rights. This paper argues that these key factors—linked to the lower status as a migrant community of the Gilbertese, a limited sharing of knowledge between communities, government blind spots and power hierarchies—explain both the disproportionate impacts of the disaster and issues that impact longer-term aid intervention and social cohesion

Warp propagation in astrophysical discs

Astrophysical discs are often warped, that is, their orbital planes change with radius. This occurs whenever there is a non-axisymmetric force acting on the disc, for example the Lense-Thirring precession induced by a misaligned spinning black hole, or the gravitational pull of a misaligned companion. Such misalignments appear to be generic in astrophysics. The wide range of systems that can harbour warped discs - protostars, X-ray binaries, tidal disruption events, quasars and others - allows for a rich variety in the disc's response. Here we review the basic physics of warped discs and its implications.Comment: To be published in Astrophysical Black Holes by Haardt et al., Lecture Notes in Physics, Springer 2015. 19 pages, 2 figure

From Top to Bottom - the Multiwavelength Campaign of V824 Ara (HD 155555)

A great deal of progress has been made in recent years in decomposing the 2-D structure in the atmospheres of late-type stars. Doppler images of many photospheres single stars, T Tauri stars, Algols, RS CV(sub n) binaries to name a few - are regularly published (Strassmeier 1996; Richards and Albright 1996; Rice and Strassmeier 1996; Kuerster et al. 1994). Ultraviolet spectral images of chromospheres appear in the literature (e.g., Walter et al. 1987; Neff et al. 1989) but are less common owing to the difficult nature of obtaining complete phase coverage. Zeeman doppler images of magnetic fields are now feasible (e.g., Donati et al. 1992). Performing Doppler imaging of the same targets over many seasons has also been accomplished (e.g, Vogt et al. 1997). Even when a true image reconstruction is not possible due to poor spectral resolution, we can still infer a great deal about spatial structure if enough phases are observed. However, it is increasingly apparent that to make sense of recent results, many different spectral features spanning a range of formation temperature and density must be observed simultaneously for a coherent picture to emerge. Here we report on one such campaign. In 1996, we observed the southern hemisphere RS CV(sub n) binary V824 Ara (P=1(sup d).68, G5IV+K0V-IV-IV) over one complete stellar rotation with the Hubble Space Telescope and EUVE. In conjunction, radio and optical photometry and spectroscopy were obtained from the ground. Unique to this campaign is the complete phase coverage of a number of activity proxy indicators that cover source temperatures ranging from the photosphere to the corona

The evolution of a supermassive binary caused by an accretion disc

The interaction of a massive binary and a non-self-gravitating circumbinary accretion disc is considered. The shape of the stationary twisted disc produced by the binary is calculated. It is shown that the inner part of the disc must lie in the binary orbital plane for any value of viscosity. When the inner disc midplane is aligned with the binary orbital plane on the scales of interest and it rotates in the same sense as the binary, the modification of the disc structure and the rate of decay of the binary orbit, assumed circular, due to tidal exchange of angular momentum with the disc, are calculated. It is shown that the modified disc structure is well described by a self-similar solution of the non-linear diffusion equation governing the evolution of the disc surface density. The calculated time scale for decay of the binary orbit is always smaller than the "accretion" time $t_{acc}=m/{\dot M}$ ($m$ is the mass of the secondary component, and $\dot M$ is the disc accretion rate), and is determined by ratio of secondary mass $m$, assumed to be much smaller than the primary mass, the disc mass inside the initial binary orbit, and the form of viscosity in the disc.Comment: to be published in MNRA