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.     

Asia's century and the problem of Japan's centrality

Japan has long been regarded as a central component of America's grand strategy in Asia. Scholars and practitioners assume this situation will persist in the face of China's rise and, indeed, that a more ‘normal’ Japan can and should take on an increasingly central role in US‐led strategies to manage this power transition. This article challenges those assumptions by arguing that they are, paradoxically, being made at a time when Japan's economic and strategic weight in Asian security is gradually diminishing. The article documents Japan's economic and demographic challenges and their strategic ramifications. It considers what role Japan might play in an evolving security order where China and the US emerge as Asia's two dominant powers by a significant margin. Whether the US–China relationship is ultimately one of strategic competition or accommodation, it is argued that Japan's continued centrality in America's Asian grand strategy threatens to become increasingly problematic. It is posited that the best hope for circumventing this problem and its potentially destabilizing consequences lies in the nurturing of a nascent ‘shadow condominium’ comprising the US and China, with Japan as a ‘marginal weight’ on the US side of that arrangement.     

The haves and have nots in Australia's Tropical North – New Perspectives on a Persisting Problem

There is significant confluence in the literature that leads one to expect groups of haves and groups of have nots in socio‐economic systems within common spatial contexts. Several economic theories suggest economic activity to be concentrated in a few core areas with geographically large ‘peripheries’ relying on one or two industries for employment and income. In the context of the north of Australia, issues of disparities in socio‐economic status between the region and elsewhere in Australia, and also within the region have been highlighted in the literature for some time. This paper discusses the contemporary situation using customised data collected and analysed for 55 river‐basin catchments in the Tropical Rivers region of northern Australia to highlight the extent of the haves and have nots problem. A range of spatial economic theories are discussed as theoretical bases for the present day situation and as pointers to revisionist approaches which may address it. Transforming the have nots to improved states of well‐being will be a costly and difficult process. Consequently, we argue that factors other than raw incomes and economic production should be reconsidered and re‐prioritised by governments as redress to the ongoing ‘problem’ of the North.     

Regional Planning in Queensland's Rangelands: Challenges and Prospects for Biodiversity Conservation

In Australia, the Commonwealth and State governments are increasingly devolving natural resource management (NRM) responsibilities to regional bodies. This move has led to the development of regional NRM plans. Native vegetation and biodiversity conservation, along with soil, pasture and water resources, are key components of the regional NRM plans in Queensland's extensive rangelands. This paper outlines and applies a set of criteria for evaluating the native vegetation and biodiversity content of accredited regional NRM plans for Queensland's rangelands. The evaluation showed considerable variation in the comprehensiveness of the information and knowledge base and management action targets among plans, including the poor articulation of impacts of excessive grazing pressure on biodiversity. The NRM plans lacked effective integration of natural resource, native vegetation and biodiversity conservation targets and actions. Several regions had too many biodiversity targets, many of which were poorly integrated. This is symptomatic of a limited understanding of rangelands as ecological systems and the lack of an integrated planning framework. We conclude regional NRM planning is not a ‘silver bullet’ for biodiversity conservation in the rangelands, but rather, it is the beginning of a long road to address complex, multi‐scale problems at a regional level.     

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.     

The Agency of Dolphins: Towards Inter‐species Embassies as Sites of Engagement with ‘Significant Otherness’

Cetacean–human interaction, at sites where free‐ranging dolphins approach humans, is occurring more than ever before. Management policies and strategies, and their underlying research, intended to protect both dolphins and humans during these interactive events, affect the quality and nature of interactivity. The agency of the dolphins, and its representation in management schemes, is analysed using Critical Discourse Analysis of selected texts from the discourse of Dolphin–Human Interaction Management (DHIM). Analysis suggests a prevailing discourse of protectionism but also reveals the possibility for a new kind of management scheme based upon an acceptance of the ‘significant otherness’ of non‐human species. This can be achieved by means of inter‐species etiquette, acknowledging the choices made by non‐humans to interact with humans. An inter‐species etiquette, coupled with multi‐species education (education across species boundaries, designed and delivered so as to enable mutually beneficial interaction), offers those non‐human animals widely referred to as ‘ambassadors’ safe places in which to be encountered. This new form of inter‐species interaction space is named an ‘embassy’.     

NEUTRON ACTIVATION ANALYSIS OF ROMAN AFRICAN RED SLIP WARE KILNS

Roman African Red Slip ware (ARS) sherds from four ARS kiln sites in modern-day Tunisia (El Mahrine, El Ala, Oudna and Pheradi Maius) have been analysed using instrumental neutron activation analysis. Multivariate statistical methods (including cluster analysis and Manhattan City Block distances), with a dilution correction applied to the data, were used to interpret the concentration data. Reference groups for each of the four kiln sites were established. Both El Mahrine and Oudna were described by two dilution-related groups. These kiln groups were all shown to be compositionally distinct from each other and suitable for use in provenance studies.