Volcano-stratigraphy and geochemistry of collision-related volcanism on the Erzurum–Kars Plateau, northeastern Turkey

The Eastern Anatolia Region exhibits one of the world's best exposed and most complete transects across a volcanic province related to a continental collision zone. Within this region, the Erzurum–Kars Plateau is of special importance since it contains the full record of collision-related volcanism from Middle Miocene to Pliocene. This paper presents a detailed study of the volcanic stratigraphy of the plateau, together with new K–Ar ages and several hundred new major- and trace-element analyses in order to evaluate the magmatic evolution of the plateau and its links to collision-related tectonic processes. The data show that the volcanic units of the Erzurum–Kars Plateau cover a broad compositional range from basalts to rhyolites. Correlations between six logged, volcano-stratigraphic sections suggest that the volcanic activity may be divided into three consecutive Stages, and that activity begins slightly earlier in the west of the plateau than in the east. The Early Stage (mostly from 11 to 6 Ma) is characterised by bimodal volcanism, made up of mafic-intermediate lavas and acid pyroclastic rocks. Their petrography and high-Y fractionation trend suggest that they result from crystallization of anhydrous assemblages at relatively shallow crustal levels. Their stratigraphy and geochemistry suggest that the basic rocks erupted from small transient chambers while the acid rocks erupted from large, zoned magma chambers. The Middle Stage (mostly from 6–5 Ma) is characterised by unimodal volcanism made up predominantly of andesitic–dacitic lavas. Their petrography and low-Y fractionation trend indicate that they resulted from crystallization of hydrous (amphibole-bearing) assemblages in deeper magma chambers. The Late Stage (mostly 5–2.7 Ma) is again characterised by bimodal volcanism, made up mainly of plateau basalts and basaltic andesite lavas and felsic domes. Their petrography and high-Y fractionation trend indicate that they resulted from crystallization of anhydrous assemblages at relatively shallow crustal levels. AFC modelling shows that crustal assimilation was most important in the deeper magma chambers of the Middle Stage. The geochemical data indicate that the parental magma changed little throughout the evolution of the plateau. This parental magma exhibits a distinctive subduction signature represented by selective enrichment in LILE and LREE thought to have been inherited from a lithosphere modified by pre-collision subduction events. The relationships between magmatism and tectonics support models in which delamination of thickened subcontinental lithosphere cause uplift accompanied by melting of this enriched lithosphere. Magma ascent, and possibly magma generation, is then strongly controlled by strike-slip faulting and associated pull-apart extensional tectonics.     

Searching for large-scale structure in deep radio surveys

We calculate the expected amplitude of the dipole and higher spherical harmonics in the angular distribution of radio galaxies. The median redshift of radio sources in existing catalogues is z  ∼ 1, which allows us to study large-scale structure on scales between those accessible to present optical and infrared surveys, and that of the cosmic microwave background (CMB). The dipole is a result of two effects which turn out to be of comparable magnitude: (i) our motion with respect to the CMB, and (ii) large-scale structure, parametrized here by a family of cold dark matter power-spectra. We make specific predictions for the Green Bank 1987 (87GB) and Parkes–MIT–NRAO (PMN) catalogues, which in our combined catalogue include ∼ 40 000 sources brighter than 50 mJy at 4.85 GHz, over about 70 per cent of the sky. For these relatively sparse catalogues both the motion and large-scale structure dipole effects are expected to be smaller than the Poisson shot noise. However, we detect dipole and higher harmonics in the combined 87GB–PMN_raw catalogue which are far larger than expected. We attribute this to a 2 per cent flux mismatch between the two catalogues. Ad hoc corrections made in an effort to match the catalogues may suggest a marginal detection of a dipole. To detect a dipole and higher harmonics unambiguously, a catalogue with full sky coverage and ∼ 10⁶ sources is required. We also investigate the existence and extent of the supergalactic plane in the above catalogues. In a strip of ± 10° of the standard supergalactic equator, we find a 3 σ detection in PMN_raw, but only 1 σ in 87 GB_raw. We briefly discuss the implications of ongoing surveys such as FIRST and NVSS and follow-up redshift surveys.     

The analysis of zoning in magmatic crystals with emphasis on olivine

Many of the observed features of zoning in magmatic phenocrysts may be due to the orientation of the section rather than inherent properties of the crystals. An ideal section for the studying of zoning in magmatic crystals has two characteristics: it goes through the center of the crystal, and is perpendicular to one or more crystal faces. Using a model zoned olivine crystal, it is possible to construct accurate zoning profiles for different types of section (centered, symmetrical and skewed). The probability of obtaining a random section which passes within x% of the center of a crystal is shown to be P=0.0x, while the probability that a random section will be within A degrees of perpendicular to a given plane is P=sin(A). A systematic approach to the study of zoned crystals is outlined. In particular, it is suggested that composition be plotted against distance cubed, in order to correct for the volume versus size problem. A method of determining if a given section goes through (or near) the center of a zoned crystal is also presented. The reasoning in this work applies to other types of magmatic crystals such as pyroxenes and plagioclase.     

Disaster Management and Community Planning, and Public Participation: How to Achieve Sustainable Hazard Mitigation

The paper offers first a brief historical overview of disaster management planning. Second, it reviews Australian and American research findings and show that they urge the field of disaster management to shift its focus from response and recovery to sustainable hazard mitigation. It is argued that in order for this shift to occur, it is necessary to integrate disaster management and community planning. Current practice seldom reflects such a synthesis, and this is one of the reasons why hazard awareness is absent from local decision-making processes. Third, it is asserted that if mitigative strategies are to be successfully implemented, then the disaster management process must incorporate public participation at the local decision-making level. The paper concludes with a case study of California's Portola Valley, which demonstrates that when public participation is integrated into disaster management planning and community planning, the result is sustainable hazard mitigation.     

The Development of the Chagas' Online Data Entry System (CODES-GIS)

This article describes a web‐based data entry and GIS‐driven mapping system designed for an ethnographic and entomological survey of Chagas’ disease, an emerging zoonotic disease, and Triatoma dimidiata, a primary vector, in the Los Tuxtlas region of Veracruz, Mexico. To better understand this disease in the region, a collaborative, multi‐disciplinary study was initiated to conduct a spatial investigation of T. dimidiata and a community‐by‐community survey of local perceptions of the disease. In order to facilitate such a collaborative effort the CODES‐GIS was developed. This system allows for (near) real‐time mapping, analyses, disease reporting, and results sharing. CODES‐GIS provides a framework for a research team working in a remote area with limited technology, software, or GIS expertise to benefit from (near) real‐time spatial analyses performed at collaborating institutions. The system is bi‐directional, where field personnel can upload data to the system for field‐based map production. Likewise, laboratory personnel can upload diagnostics data for viewing by field personnel. In this way, the system provides a virtual link between the field and the laboratory to increase the speed at which results are returned to the local community. The CODES‐GIS is described along with a selection of study results.     

Estimating the diffuse attenuation coefficient from optically active constituents in UK marine waters

We report a study of the attenuation of submarine Photosynthetically Active Radiation (PAR) in relation to the concentrations of Optically Active Constituents (OACs) in a range of water types around the United Kingdom. 408 locations were visited between August 2004 and December 2005. The diffuse attenuation coefficient (K_d) was estimated from profiles of downwelling PAR. Concentrations of Suspended Particulate Matter (SPM) were measured gravimetrically and concentrations of phytoplankton chlorophyll (chl) were measured by fluorometrically. Chromophoric Dissolved Organic Matter (CDOM) was measured either by fluorescence or as its proxy, salinity.     

Incorporating geographies of health into public policy debates: The GeoHealth Laboratory

Abstract:  The restricted influence of geographers in the policy arena has been the source of some angst. This paper reports on a new initiative at the University of Canterbury, which aims to strengthen geography's contribution to health policy debates in New Zealand. The GeoHealth Laboratory is a joint initiative between the Department of Geography and Public Health Intelligence group at the Ministry of Health that seeks to provide a pathway for the integration of health geography research into policy development. This new facility aligns the expertise in health geography, GIS and other spatial analytical methods with policy-relevant research priorities. An overview of the strategic aims of the GeoHealth Laboratory is provided along with some examples of recent research activities that are contributing to understandings of the health landscape in New Zealand. It is argued that such partnerships provide important opportunities for geographers to engage with policy-relevant issues.