Formation of atoll garnets in the UHP eclogites of the Tso Morari Complex,Ladakh, Himalaya   总被引：1，自引：0，他引：1  

Mallika K Jonnalagadda  Nitin R Karmalkar  Raymond A Duraiswami  Shivani Harshe  Sarah Gain  William L Griffin 《Journal of Earth System Science》2017,126(8):107

The eclogites of the Tso Morari Complex, Ladakh, NW Himalayas preserve both garnets with spectacular atoll textures, as well as whole porphyroblastic garnets. Whole garnets are euhedral, idiomorphic and enclose inclusions of amphibole, phengite and zoisite within the cores, and omphacite and quartz/coesite towards the rims. Detailed electron microprobe analyses and back-scattered electron images show well-preserved prograde zoning in the whole garnets with an increase in Mg and decrease in Ca and Mn contents from the core to the rim. The atoll garnets commonly consist of euhedral ring over island/peninsular core containing inclusions of phengite, omphacite and rarely amphibole between the core and ring. Compositional profiles across the studied atoll grains show elemental variations with higher concentrations of Ca and Mn with low Mg at the peninsula/island cores; contrary to this low Ca, Mn and high Mg is observed at the outer rings. Temperature estimates yield higher values at the Mg-rich atoll garnet outer rings compared to the atoll cores. Atoll garnet formation was favoured by infiltration of fluid formed due to breakdown of hydrous phases, and/or the release of structurally bounded OH from nominally anhydrous minerals at the onset of exhumation. Infiltration of fluids along pre-existing fracture pathways and along mineral inclusion boundaries triggered breakdown of the original garnet cores and released elements which were subsequently incorporated into the newly-grown garnet rings. This breakdown of garnet cores and inward re-growth at the outer ring produced the atoll structure. Calibrated geo-thermobarometers and mineral equilibria reflect that the Tso Morari eclogites attain peak pressures prior to peak temperatures representing a clockwise path of evolution.  相似文献   

Collecting <Emphasis Type="Italic">Ophiocordyceps sinensis</Emphasis>: an emerging livelihood strategy in the Garhwal,Indian Himalaya     

Laura Caplins  Sarah J. Halvorson 《山地科学学报》2017,14(2):390-402

In the Garhwal of Uttarakhand, India, the Bhotiya, an ethnically and culturally distinct tribal group, were historically engaged in seasonal migration (i.e. transhumance) to take advantage of scarce mountain resources and trade relations with Tibet. This livelihood practice has all but disappeared. Households are adapting to these changing circumstances by engaging in the collection and sale of the valuable alpine medicinal fungus Ophiocordyceps sinensis, widely known as Cordyceps. The collection of this fungus has exploded, emerging as a lucrative yet high-risk livelihood strategy for many Bhotiya communities. The Bhotiyas’ historic herding and trade-based interactions and knowledge of these alpine environments where Cordyceps are found uniquely positions them to access this valuable biological resource. Elsewhere in the Himalayan region, some households are earning as much as two-thirds of their income from the collection of Cordyceps; in China Cordyceps is now listed as an endangered species due to intense over-exploitation in the Tibetan Plateau. This paper seeks to fill the void in the scientific literature on the social, ecological and economic aspects of the emerging Cordyceps trade in the Garhwal. Our study investigates the socio-spatial dimensions of Cordyceps collection in the high alpine meadows. We document how a fusion of local knowledge and practice with alpine mountain systems has served to reinvigorate the economic integrity of mountain communities at a time of rapid socio-economic change and to reimagine a new relationship between alpine resources and community well-being. The article offers suggestions to address the sustainability of both Cordyceps collection and livelihood activities which hinge on this fungus population. We find a need for (1) community-based conservation measures that are rooted in (2) secure resource access rights for local communities to continue sustainable collection and sale of Cordyceps and (3) participatory-and science-based processes for determining appropriate local collection numbers.  相似文献   

Diasporas – By Stéphane Dufoix     

Sarah  Starkweather 《The Geographical journal》2010,176(1):117-118

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Root properties of vegetation communities and their impact on the erosion resistance of river dikes   总被引：1，自引：0，他引：1       下载免费PDF全文

Wouter Vannoppen  Jean Poesen  Patrik Peeters  Sarah De Baets  Bart Vandevoorde 《地球表面变化过程与地形》2016,41(14):2038-2046

Predicted climate change and the associated sea level rise poses an increased threat of flooding due to wave overtopping events at sea and river dikes. To safeguard the land from flooding it is important to keep the soil erosion resistance at the dikes high. As plant roots can be very effective in reducing soil erosion rates by concentrated flow, the main goal of this study is to explore the variability in root system characteristics of five dike vegetation communities along the Scheldt River (Belgium) and to assess their effectiveness in controlling soil erosion rates during concentrated flow. This study is the first one to investigate systematically the erosion‐reducing potential of the root properties of representative dike vegetation communities in a temperate humid climate. Results show that the presence of Urtica dioica resulted in large differences in root length density (RLD) among dike vegetation communities. Observed RLD values in the topsoil ranged from 129 to 235 km m^‐3 for dike vegetation communities without U. dioica, while smaller values ranging from 22 to 58 km m^?3 were found for vegetation communities with U. dioica. The erosion‐reducing effect of the dike vegetation communities was estimated based on a global Hill curve model, linking the RLD to the soil detachment ratio (SDR; i.e. the ratio of the soil detachment rate for root‐permeated topsoils to the soil detachment rate for root‐free topsoils). Concentrated flow erosion rates are likely to be reduced to 13–16% of the erosion rates for root‐free topsoils if U. dioica is absent compared to 22–30% for vegetation communities with U. dioica. Hence, to maintain a high resistance of the soil against concentrated flow erosion it is important to avoid the overgrowth of grassland by U. dioica through an effective vegetation management. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Foreign Direct Investment in the Czech Republic     

Gill Valentine  Sarah Holloway 《The Professional geographer》2013,65(1):71-83

Children are considered particularly important in debates about the possibilities and dangers of information and communication technologies (ICT). Discourses on ICT contain paradoxical representations of childhood. On the one hand, unlike most other understandings of child/adult relations, these discourses assume children to be equally, if not more, technologically competent than adults. On the other hand, children’s very competence at using ICT is alleged to be putting them “at risk” of abuse or corruption. This paper addresses these moral panics about children and ICT by exploring to what extent and why parents are concerned about their children’s safety in on-line space. In doing so the paper reflects on the extent to which anxieties about children in cyberspace replicate concerns about public outdoor space and the way networked computers emerge as different tools in different households.  相似文献   

Emerging trends in urbanizing Palestine: neglected city-builders beyond the occupation     

Marco Chitti  Sarah Moser 《Urban geography》2013,34(7):1010-1017

In this article, we draw attention to trends in land transformation in the West Bank since the Second Intifada, after which a surge of investment from Gulf countries entered Palestine, almost exclusively in the West Bank. The occupied Palestinian territories have attracted a great deal of attention from media and academics, yet the vast majority of scholarship focuses on the conflict and the variety of social, economic, and political repercussions of the on-going Israeli occupation. While the occupation has undeniably serious impacts on every aspect of life for Palestinians, the near-exclusive focus on the conflict means that significant new trends, such as urban mega-developments and emerging market-based urbanisation processes, have been largely overlooked. We outline three directions for future research: the assemblage of “neglected city-builders” shaping current urbanization processes in Palestine; the ideas, policies, and norms circulating in the West Bank; and the social, spatial, economic, and other impacts of these new urban developments.  相似文献   

A land-use-based modelling chain to assess the impacts of Natural Water Retention Measures on Europe’s Green Infrastructure     

Sarah Mubareka  Christine Estreguil  Claudia Baranzelli  Carla Rocha Gomes  Carlo Lavalle  Barbara Hofer 《International journal of geographical information science》2013,27(9):1740-1763

This article details the process of integrating models to answer a specific policy-driven question: ‘What could be the impact of proposed Natural Water Retention Measures (NWRMs) on Europe’s Green Infrastructure (GI)?’ It describes the new Land Use Modelling Platform (LUMP), now enabling a high spatial scale (100-m) and large coverage (pan-European), whereby several sector-specific models contribute to assessing the impact of regional-level policy on a given spatial topic of concern. The configuration (land claims and land allocations modules) and calibration (accessibility and biophysical suitability) of the LUMP are explained. Four NWRM scenarios (riparian areas, afforestation, grassland and baseline scenario) are configured to run the simulations. For the reference: year 2006, the spatial representation of GI is based on land-use features of a refined version of the CORINE Land Cover (CLC), and resumed as connected components made of nodes and links.

Mathematical morphological image processing and network graph theory model, available from the free software package GUIDOS (the Joint Research Center of the European Commission), enabled the measurement of the GI connectivity and identified most critical links. Results show that the competition for land claimed by different economic sectors, combined with policy-driven rule-sets for the implementation of different NWRMs, yields very different results for the 2030 land-use projections, and subsequently for the morphology of GI. Three indicators associated with the morphology of GI are computed in order to assess the model outputs for 2030. The indicators are computed to answer the following questions: (1) How is the quantity of GI affected by each of the NWRM, and what proportion of that GI is most valuable? (2) What is the location of the most critical nodes and connectors of GI, and what land-use conversions occur under these? (3) Are the average components getting larger or smaller?

Whereas the grassland measure results in the largest net increase of GI, the afforestation measure results in the overall largest number of hectares of key nodes and links within the network. Land conversions occur under the critical GI nodes and links, with a large increase in agricultural areas, especially for the riparian measure under critical nodes and the grassland measure under critical links. Also predominant is the swapping of land from pasture to forest under critical links with the afforestation measure. The riparian measure most increases the average size of GI components, and all three measures contribute to bridging two large components which were divided in the 2006 land-use map, thus increasing the size of the largest component by more than 50%.  相似文献   

Mechanisms of tropical precipitation biases in climate models     

Kim  Hanjun  Kang  Sarah M.  Takahashi  Ken  Donohoe  Aaron  Pendergrass  Angeline G. 《Climate Dynamics》2021,56(1-2):17-27

Climate Dynamics - We investigate the possible causes for inter-model spread in tropical zonal-mean precipitation pattern, which is divided into hemispherically symmetric and anti-symmetric modes...  相似文献   

An integrated approach for evaluating the effectiveness of landslide risk reduction in unplanned communities in the Caribbean     

Elizabeth Holcombe  Sarah Smith  Edmund Wright  Malcolm G. Anderson 《Natural Hazards》2012,61(2):351-385

Despite the recognition of the need for mitigation approaches to landslide risk in developing countries, the delivery of ‘on-the-ground’ measures is rarely undertaken. With respect to other ‘natural’ hazards, it is widely reported that mitigation can pay. However, the lack of such an evidence base in relation to landslides in developing countries hinders advocacy amongst decision makers for expenditure on ex-ante measures. This research addresses these limitations directly by developing and applying an integrated risk assessment and cost–benefit analysis of physical landslide mitigation measures implemented in an unplanned community in the Eastern Caribbean. In order to quantify the level of landslide risk reduction achieved, landslide hazard and vulnerability were modelled (before and after the intervention), and project costs, direct and indirect benefits were monetised. It is shown that the probability of landslide occurrence has been substantially reduced by implementing surface-water drainage measures and that the benefits of the project outweigh the costs by a ratio of 2.7–1. This paper adds to the evidence base that ‘mitigation pays’ with respect to landslide risk in the most vulnerable communities—thus strengthening the argument for ex-ante measures. This integrated project evaluation methodology should be suitable for adoption as part of the community-based landslide mitigation project cycle, and it is hoped that this resource, and the results of this study, will stimulate further such programmes.  相似文献   

Vulnerability and risk: comparing assessment approaches     

Sarah Wolf 《Natural Hazards》2012,61(3):1099-1113

The concepts vulnerability and risk are of great importance in the fields of climate change and natural hazards. Confusion is asserted in the terminology used by the respective communities, and a large conceptual literature has not solved this problem. This affects the communication within and between the two communities and the comparison of results from vulnerability and risk assessments. This paper argues that the main difference between methods to assess vulnerability and risk in the climate and the disaster communities is not a conceptual one, but rather different terminologies are used. This point is made using a formal framework of vulnerability to climate change that makes the structure of vulnerability and risk assessments explicit. The framework distinguishes three assessment approaches in the field of vulnerability to climate change, which recur—under different labels—in the risk assessment approaches analysed. While within each community, the same terms are ambiguously used to refer to more than one assessment approach, the confusion is enhanced between the two communities by using different labels for very similar approaches. As an application of the results, similarities and differences between two assessment tools are analysed: the Dynamic Interactive Vulnerability Assessment model (DIVA) for the case of vulnerability to climate change and the CATastrophe SIMulation model (CatSim) for risk of natural hazards.  相似文献