Oscillatory zoning and trace element incorporation in hydrothermal minerals: insights from calcite growth experiments

Oscillatory zoning and fine‐scale variations in trace element chemistry are commonly observed in hydrothermal minerals. It has been suggested that fine‐scale chemical variations are caused by extrinsic changes in the parent hydrothermal system, such as varying fluid composition, pressure or temperature, as well as changes in mineral growth rate. In this study, LA–ICP–MS (laser ablation, inductively coupled plasma mass spectrometer) analyses were carried out on calcite crystals grown in Ca–NH₃–Cl solutions doped with rare earth elements (REE). The variety of crystal morphologies observed (euhedral to acicular), likely relate to variations in trace element abundance and calcite supersaturation state. Crystals display oscillatory and sector zoning, with significant variations in REE concentrations among zones. Cyclic variations in REE concentrations (exceeding 10‐fold) occur over distances of <1 mm along the growth direction of acicular calcite crystals. In general, trace element concentrations decrease during progressive crystal growth, implying that the concentration of trace and REEs within crystals reflects the overall composition of the growth solution. However, bulk changes in crystal composition are modulated by fine‐scale (<1 mm) variations, which are inferred to be caused by growth‐rate‐controlled incorporation of trace elements. These results have important implications for using hydrothermal minerals to infer fluctuations in fluid compositions in ancient, exhumed hydrothermal systems.     

Doing Building Work: Methods at the Interface of Geography and Architecture

This paper summarises the methodological approach taken in an interdisciplinary project involving geographers and architects. The project charted the diverse afterlives of the modernist‐inspired, state‐sponsored, residential high‐rise, and did so drawing on two cases: Red Road Estate in Glasgow and Bukit Ho Swee Estate in Singapore. In offering a specific account of, and reflection upon, the methodologies used in the High‐rise Project, we hope to advance the methodological repertoire of human geography generally and contribute further to the new wave of scholarship on geography and architecture.     

FAIR SHARES FOR THE ZONE: ALLOCATING HEALTH-CARE RESOURCES FOR THE NATIVE POPULATIONS OF THE SIOUX LOOKOUT ZONE, NORTHERN ONTARIO

The purpose of this paper is to explore issues of healthcare resource allocation for a Canadian native population, that of Sioux Lookout Zone, within the context of the total provincial population. We argue that a fair share of provincial health resources for any population must be based on a population needs approach. The paper begins by establishing a method to measure a fair share of healthcare resources. It goes on to establish why a fair share is important in the light of native health conditions in general and with respect to this specific population. The fair share is then calculated and illustrated with reference to particular health-care programs. Finally, there is discussion of the methodological and policy issues that arise from this research.     

‘A Tiny Little Footnote in History’: Conservative Centre Forward

In May 1985, two years after he had returned to the back benches, Francis Pym launched the first organised display of dissent within the parliamentary Conservative Party against Margaret Thatcher's leadership: Conservative Centre Forward. Those Conservative MPs who joined the group were very much believers in One Nation Conservatism. Conservative Centre Forward survived for barely a week after going public; it rapidly collapsed amid accusations of disloyalty and inept leadership. The group proved to be a short-lived experiment which achieved little of note and exposed those who were involved to widespread ridicule. Yet, it was precisely because Conservative Centre Forward collapsed so quickly and achieved so little that it was significant. In its own way, the short life of the group provided a revealing commentary upon the character of the mid-1980s Conservative Party. It was a party which, on the one hand, was moving inexorably to the right and therefore ever further away from the values of One Nation Conservatism which Conservative Centre Forward espoused. On the other hand, it was a party which was still traditional enough to view open displays of dissent, of whatever magnitude, as a threat to the unity upon which its continued electoral success depended.