Coastal marinas in South Australia: environmental issues and strategic planning

Coastal marina proposals have recently been the subject of significant environmental controversy in South Australia. In response, the South Australian government formed a Marina Assessment Advisory Committee to produce guidelines for the planning and development of coastal marinas, examine the level of demand for marina berths and recommend suitable sites. This article outlines the characteristics of coastal marina developments in South Australia and examines some of the results of the marina committee's work in light of the planning problems associated with marina development.     

Reconstruction and visualisation of melt topology in veined microdioritic enclaves

A number of xenocrystic microdioritic enclaves within the Ross of Mull Granite contain narrow veins of monzonitic material that have formed through the selective partial fusion of granitic magma mechanically incorporated into the microdiorite magma. Field evidence suggests that, as melting of the granitic material ensued, a monzonitic melt formed and exfiltrated from the surrounding microdioritic matrix resulting in Saffman–Taylor instabilities and the development of viscous fingering phenomena. The monzonitic melt network is now preserved as monzonitic veins. Mechanical serial sectioning through a representative veined microdioritic enclave shows that: (a) the topology of the veins is complex but crudely polyhedral, (b) there is porosity (monzonitic melt fraction) variation throughout the length of the veined enclave and (c) that the monzonitic veins are interconnected in three dimensions. Using image analysis software, the total porosity of individual veined enclave sections has been estimated, along with the variation in porosity with depth. Three dimensional rendering and animation software has been used to reconstruct and visualise the monzonitic melt network using Apple QuickTime™ software. The above method provides a cheap and powerful way of visualising remnant macroscopic transport properties (such as connectivity and melt topology) in partially molten igneous rocks.Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Metamorphic olivine in ultramafic rocks from Western Australia

Textural relationships plus associated mineralogy are compatible with a metamorphic origin for some olivines in altered ultramafics. Upper amphibolite facies PT conditions are indicated.     

Mg isotope heterogeneity in the Allende meteorite measured by UV laser ablation-MC-ICPMS and comparisons with O isotopes

First results from a new UV laser ablation MC-ICPMS method for measuring Mg isotope ratios in situ in meteoritical materials show that there are mass-dependent variations in δ²⁵Mg and δ²⁶Mg up to 1.5 ‰ per amu in chondrules and 0.3‰ per amu in a CAI from the Allende meteorite. In both cases the mass-dependent fractionation is associated with alteration. Comparisons with laser ablation O isotope data indicate that incorporation of pre-existing grains of forsterite with distinct Mg and O isotopic compositions and post-formation alteration both contributed to the variability in Mg isotope ratios in the chondrules, resulting in a correlation between high δ²⁵Mg and low Δ¹⁷O. The laser ablation analyses of the CAI show that high-precision determinations of both δ²⁵Mg and δ²⁶Mg can be used to discriminate features of the ²⁶Al-²⁶Mg isotope system that are relevant to chronology from those that result from element mobility.     

The effect of internal gas pressurization on volcanic edifice stability: evolution towards a critical state

Results from simple physical and numerical models investigating the effects of increased internal pore‐fluid pressures of a Mohr–Coulomb volcanic edifice are presented. Physical experiments make use of a heap built from angular sand on top of a stiff substrate of variable angle, with the provision for injection of internal fluid (gas) pressures into the base. The resulting failure geometries arising from internal pressurization of the model appear similar to some natural examples of sector collapse. Two‐dimensional limit equilibrium models analysing 42 500 possible failure surfaces were run with internal pressures (P₀) in the range 5–35 MPa, and show that the potential critical failure surface migrates to increasingly deeper levels with increasing internal pressure. Although internal pressurization alone is unlikely to reduce the factor of safety (F_S) below unity, the edifice is driven towards a state of criticality that will render in susceptible to any internal or external perturbations.     

Embedding the reforms in New Zealand schooling: After neo-liberalism?

Two decades of reforms to the state in New Zealand have altered policy, its making and the ways in which it is realised in micro settings. This paper uses the example of schooling to examine the rationality of these reforms, their spatial logic and what they mean for our understanding of the national state. It examines the development and practices of the Education Review Office (ERO), the body established under the reforms to evaluate and audit the performance of schools in the new national education `system'. The paper interprets neo-liberalism as a governmentality, and argues that the development of new managerial technologies of remote control such as contract and audit constitute a spatial model of control. The paper suggests that this model encourages, and relies for its efficacy upon, the cultivation of neo-liberal subjectivities. It argues that although the political projects working through the reforms have shifted, the altered rationality of the state and the models of control erected to secure it define an enduring and neo-liberalising social transformation. The shift to the `Third Way' in New Zealand's political and social economy is underpinned by neo-liberalising processes, which continue to reorganise social and economic spaces. This revised version was published online in July 2006 with corrections to the Cover Date.     

香港九龙大坑东地下蓄水方案数值研究

香港九龙大坑东地下蓄水方案(Tai Hang Tung Storage Scheme-THTSS)是香港西九龙渠道改善二期计划的一个重要组成部分,其目标是解决香港九龙繁华拥挤、人口稠密的商业中心旺角一带的洪水淹没问题。THTSS即是在经常洪水淹没区域(大坑东和界限街水渠交接处)上游足球场下面建立一个100 000 m3的地下蓄水池。本文建立了一个能处理明渠缓流和急流、封闭管道有压流、侧流堰和渠道汇合处过渡流于一体的一维水力数学模型,用1:22正态物理模型恒定流下的结果进行验证。数值模型计算了在50年一遇暴雨下,非恒定洪水在不同的侧流堰方案下的流动过程。结合物理模型试验结果,选择最佳的地下蓄水方案。计算结果表明,大坑东地下蓄水方案确实能加强旺角地区地洪水控制能力,并能通过50年一遇暴雨的洪水。     

Kaolinisation of granite in an urban environment

Under natural acid and wet conditions, one of the main weathering processes affecting granitic rocks is the kaolinisation of Na, Ca and K-feldspar minerals by H₂O + CO₂ attack. We here report the occurrence of authigenic kaolinite on the surface of an eighteenth century granitic monument covered with sulphate-rich weathering patinas. We suggest that, in humid mesothermic climates, anthropogenically derived gaseous SO₂ from air pollution is responsible for accelerated kaolinisation of feldspars in an urban environment; SO₂ from air pollution thus plays a dual role in the weathering of silicate rocks being responsible for the well known sulphation of Ca-bearing materials leading to the formation of sulphate salts such as gypsum as well as the weathering of feldspar minerals to kaolinite. The kaolinisation reaction weakens the granite microfabric leading to enhanced decay of the building stone.