The glaciotectonic deformation of Quaternary sediments by fault-propagation folding

Fault-propagation folding is an important yet seldom recognised structural style within sediments affected by glacier-induced deformation. Fault-propagation folds develop in the hanging wall of low angle thrust faults and compensate part of the slip along the fault. Field examples are recognised across northern Europe, in glaciotectonic complexes of north Germany, Wales and the Isle of Man. The recognition of the fault-propagation fold mechanism in glaciotectonic deformation is important because resultant structures are related to exactly the same phase of deformation (i.e. the same phase of ice advance), and thus play a critical role in analyses of the temporal and spatial evolution of glacier-induced deformation. Some field examples show monoclinal geometries that are in good agreement with predictions of trishear kinematic theory. The trishear approach is appropriate to model these structures because the structures analysed in the field and simulated below show characteristics that are compatible with fault-propagation folds that were produced by trishear kinematics. The curved forelimb and the monocline geometry of the fault-propagation folds fit to the trishear model. The occurrence of footwall synclines is also in good agreement with trishear kinematics. These synclines show the typical thickening of the strata in the hinge. With respect to the modelling output, most important factors for the structural evolution of the fault-propagation folds is the ramp angle of the thrust, the position of the tip line and the propagation-to-slip ratio along the fault. This fits to observations made by previous studies at large scale fault-propagation folds in fold-and-thrust belts.     

Remote sensing mapping of the regeneration of coastal natural habitats in Singapore: Implications for marine conservation in tropical cities

Rapid urbanization has resulted in the loss of coastal and marine habitats in cities worldwide. The effective conservation of urban coastal ecosystems requires detailed knowledge of their spatial distribution, necessitating high-resolution mapping. Our study produces a high-resolution coastal and marine habitat map and shoreline map for the tropical city-state of Singapore created through pixel-based supervised classification of satellite imagery, bathymetry data and expert ground knowledge. These maps can be used as a base reference for multiple applications including ecological research, conservation and urban planning. They also help identifiy trends in the extent of key coastal habitats, providing insight into their differing levels of vulnerability to loss and potential for restoration to ensure long-term resilience. The method used for mapping shoreline typologies and resulting insights gained, can guide other rapidly urbanizing coastal cities on strategies to assemble useful spatial knowledge for effective conservation of their urban coastal ecosystems.     

Time series analysis of the 10 000 yr geomagnetic secular variation record from SE Australia

Summary. A 10 000 yr continuous secular variation record from intensively dated lake sediments in SE Australia has been subjected to periodogram and maximum entropy method analysis. Tests on synthetic data reveal some of the limitations of the latter method, particularly when applied to complex number series. Anticlockwise precession of the magnetic vector at a period of 5000 ± 1000 yr is tentatively ascribed to dipole precession, and clockwise precession at a period of about 2800 yr is probably due to westward drift of features of the non-dipole field.
The effect of calibrating the radiocarbon time-scale is important and results in periodicity shifts of up to 25 per cent. Even for well-dated lacustrine sequences power spectra are poorly constrained: it is thus possible that the geomagnetic secular variation on a time-scale of thousands of years is more uniform than often supposed. Mismatches between declination and inclination spectra can arise as a natural consequence of certain types of source mechanism and should not be simply attributed to figments of the analysis employed.     

Ferrian tourmaline from Bungonia,New South Wales

New chemical, X‐ray and cell dimension data are presented for ferrian tourmaline in quartz‐tourmaline rock at three localities near Bungonia, New South Wales. The tourmaline is fine‐grained, normally euhedral, and forms up to 90% of the rock. It shows restricted solid solution between dravite and ferridravite, although some grains are zoned and others have an irregular, bipartite chemical variation. Tourma‐linisation is interpreted as being.related to late‐stage volatile emanations from the Marulan Batholith.     

Yanama budyari gumada: reframing the urban to care as Darug Country in western Sydney

ABSTRACT

In non-urban places of Australia, caring-as-Country frames natural resource management (NRM) as a practice of reciprocal, more-than-human care-giving (S. Suchet-Pearson, S. Wright, K. Lloyd, and L. Burarrwanga. 2013. ‘Caring as Country: towards and ontology of co-becoming in natural resource management.’ Asia Pacific Viewpoint 54 (2): 185–197). Caring-as-Country is an idea that encapsulates the entangled, reciprocal relationships that people have with, and as part of, agentic more-than-human worlds. In more urbanised places, however, practices of caring-as-Country are often unrecognised, undervalued and undocumented. In this paper we make explicit practices of caring, healing and rejuvenation at Yellomundee Regional Park, Darug Country in western Sydney. Our discussion of care, entanglement and reciprocity at Yellomundee focuses on two specific activities that embody caring-as-Country: the return of cultural burns and sustained presence on Country in the form of Darug-led culture camps. The Darug principle of yanama budyari gumada, to ‘walk with good spirit’, embodies and invites new ways of thinking and practising intercultural caring-as-Country in heavily colonised, urban places like Yellomundee. As we document the practices arising from this invitation, we consider its far-reaching implications for NRM and planning, and we expand on the importance of geographies of care for unceded urban places.     

Tracer diffusion of some alkali,alkaline-earth and transition element ions in a basaltic and an andesitic melt,and the implications concerning melt structure

The diffusion properties of Na, Cs, Sr, Ba, Co, Mn, Fe and Sc ions in a basaltic and an andesitic melt have been determined experimentally using the radiotracer residual-activity method, and narrow platinum capillaries, over the temperature range 1,300–1,400° C. Diffusion of all cations follows an Arrhenius relationship; the values of the activation energies range from 24 kcal mol^–1 for Na to 67 kcal mol^–1 for Co in the andesitic melt, and from 39 kcal mol^–1 for Na to 65 kcal mol^–1 for Cs in the basaltic melt. Relative diffusivities in the basaltic melt, but not in the andesitic melt, correlate with assumed ionic radii values. Each cation, except Na⁺, diffuses faster in the basaltic melt than in the andesitic melt over the studied temperature range. Sodium shows similar diffusivity in the two melts.Compensation diagrams incorporating new and some previously-published data indicate that Cs probably diffuses by different mechanisms in different silicate glass and melt systems. Iron has a relatively high activation energy which is consistent with its part occupancy of tetrahedral co-ordination polyhedra.     

Sinks of iron and manganese in underground coal mine workings

The sources and sinks of manganese in underground coal mine workings are poorly understood compared to those of iron. The geochemical system in the secondary egress drift of Caphouse Colliery near Horbury, UK, is an ideal system for studying these processes. Five locations along the drift and four secondary inflows to the drift were sampled 24 times through the year commencing May 2005. During the sampling period, the pH in the main channel varied from 6.73 to 7.93 and increased along the flow path. The secondary inflows to the drift from the strata were of higher alkalinity (mean = 385 mg/L as CaCO₃) than the main flow (mean = 330 mg/L as CaCO₃); the affects of mixing between the less alkaline main channel and the more alkaline secondary inflows and of carbon dioxide exsolution are evident in the form of carbonate and hydroxide precipitates. SEM and XRD analysis of precipitates collected from the drift confirm the presence of calcium and manganese carbonates and ferric hydroxide. PHREEQC speciation and solubility modelling confirms supersaturation of the water in the main channel with respect to ferric oxy-hydroxides; iron, manganese, magnesium and calcium carbonates; and manganese oxides. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Numerical aspects of time elements

Numerical results have shown that the use of time elements with time transformations provides increased accuracy in the numerical solution of gravitational systems.To gain additional accuracy improvements, it appears that the time and the time element should be calculated from quantities that have been adjusted so as to satisfy the energy integral exactly.We also have found that by reducing the growth of the time element to being nearly linear rather than quadratic causes an increase in the magnitude of the local truncation error in the solution but with a decrease in the rate of growth of the truncation error.