Heartbeat of a mountain: diagnosing the age of depositional events in the Karoo (Gondwana) Basin from the pulse of the Cape Orogen     

J. P. le Roux 《International Journal of Earth Sciences》1995,84(3):626-635

Careful consideration of the effects of the Cape orogeny on sedimentation in the Carboniferous-Jurassic Karoo Basin provides an indirect tool for accurately dating these rocks. Fossil and radiometric data, especially when combined with sedimentological and structural information, yield partly overlapping age brackets which can be used to correlate the successive tectonic pulses with specific depositional events. Application of these principles to associated basins in Gondwanaland can provide a firm foundation for more dependable stratigraphic correlation on a global scale. The exercise also suggests that a number of widely held opinions on the age of certain stratigraphic units in the Karoo Supergroup may be incorrect.  相似文献   

Access tunnel convergence prediction in longwall coal mining     

A. Majdi  F. P. Hassani 《Geotechnical and Geological Engineering》1989,7(4):283-300

Summary The paper describes theoretical andin situ studies of tunnel deformation in longwall coal mining. It develops a method to predict tunnel convergence profiles from the faceline in longwall mining. The method accounts for the effect of panel width, extracted seam height, deformation moduli of the goaf material and coal pillar, depth of cover,in situ structural defects, tunnel shape and tunnel size in addition to the strength characteristics of surrounding strata. The analytical technique has been validated by reference toin-situ deformation measurements in 26 face-access tunnels in Cape Breton Coalfield mines. Based on this method a series of vertical convergence profiles for different depths and extracted panel widths have been presented.  相似文献   

Disentangling seafood value chains: Tourism and the local market driving small-scale fisheries     

《Marine Policy》2016

Identifying socio-economic drivers of small-scale fisheries is a fundamental step to understand impacts and pressures on fishery resources, and the behaviour of seafood trade actors. It is especially relevant for developing countries where such information is usually lacking and fisheries management is greatly needed. To address this gap, this study maps the structure of value chains of fish and marine invertebrates caught by small-scale fisheries from São Vicente, Cape Verde (West Africa), and examines the main socio-economic drivers behind the seafood trade on the island. Specifically, it shows how drivers, such as tourism and the local market, shape the preferences for certain species and how they affect the distribution of income among actors involved in the seafood trade. To collect this information, interviews were done with fishers, small-scale traders, market vendors, and restaurant owners, in all fishing communities of the island of São Vicente, in 2015. Tourism and the local market drive the exploitation of a wide variety of marine species, from small demersal low trophic level fish and marine invertebrates, to large pelagic high trophic level fish species. Moreover, the local seafood market, and especially tourism dynamics, contribute to the unequal distribution of income among actor groups, benefiting mostly restaurant owners due to their direct access to tourist consumers. Such findings have implications for local fishery resources management, food security, and fishing communities’ livelihoods.  相似文献   

The murky waters of the second wave of neoliberalism: corporatization as a service delivery model in Cape Town     

《Geoforum》2004,35(3):375-393

This article reviews how the process of corporatization transforms public sector management by adopting private sector principles. It argues that corporatization, as an institutional form emerging from a second wave of neoliberalism, threatens to undermine the democratic accountability of local authorities by virtue of restructuring the state in ways that are invisible to the public yet with highly negative outcomes for low-income communities. The article provides a case study on the water sector in Cape Town, South Africa by tracing the local authority's adoption of three cost-recovery policies and their impacts on low-income households over a five year period (1997-2001). Engineers are the key agents in the promotion of cost-recovery policies in the efforts to deliver services more `efficiently'. While these officials are highly skilled professionals in dealing with the technical side of the production process, they lack the social training necessary to deal with the politics of distribution. The prominence of the neoliberal agenda in urban management can be in part be attributed to the power of the technical over the political as engineers displace politicians in the deliberations over how to deliver services to poor areas of the city.  相似文献   

Mapping narratives of urban resilience in the global south     

《Global Environmental Change》2019

In the context of global environmental change much hope is placed in the ability of resilience thinking to help address environment-related risks. Numerous initiatives aim at incorporating resilience into urban planning practices. The purpose of this paper is to open up a conversation on urban resilience by unpacking how diverse science methods contribute to the production of different narratives of urban resilience mobilizing different experts and forms of evidence. A number of scholars have cautioned against uncritical approaches to resilience and asked what resilience means and for whom, also pointing out the normative dimension of the concept. Building on this emerging scholarship we use insights from science and technology studies (STS) and critical social sciences to look at the knowledge infrastructures and networks of actors involved in the development of resilience strategies. Drawing on fieldwork in Manila, Nairobi, and Cape Town, we map different narratives of urban resilience identifying the ways in which science serves to legitimate or alienate particular perspectives on what should be done. We discuss the multiple roles that science methods have for resilience planning. Whereas urban resilience is often portrayed as consensual, we show that a range of narratives, with diverse socio-material implications, exist at the city level. In this way we unearth the conflict that lies beneath an apparent consensus for resilience policy and outline future research directions for urban sustainability.  相似文献   

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND‐REDISTRIBUTION PROGRAM*     

WILLIAM G. MOSELEY  BRENT McCUSKER 《Geographical review》2008,98(3):322-338

ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land‐reform programs. In this study we examine land‐redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross‐section of projects in these two locales we develop a political ecology of stymied land‐reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white‐owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land‐redistribution beneficiaries, as well as on an analysis of land‐use change in Limpopo Province.  相似文献   

Re-evaluation of Rostraria bierii Tokioka, 1970 (Annelida) from Seto,Japan as a magelonid,with a review of the Magelonidae of the western Pacific     

Mortimer Kate  Mills Kimberley  Gil Jo?o 《海洋学报(英文版)》2022,41(3):61-69

  相似文献   

高温高压改色处理Ⅰa型褐色钻石的光谱鉴定特征     

宋中华  陆太进  唐诗  高博  苏隽  柯捷 《岩矿测试》2020,39(1):85-91

Ⅱa型钻石的高温高压改色及褪色研究已开展了大量工作,然而对Ⅰa型Cape系列褐色钻石在高温高压处理条件下的行为尚不明确。为解析实验室钻石鉴定工作中遇到的黄色钻石颜色成因问题,本文选取了Ⅰa型Cape系列褐色钻石作为研究对象,进行高温高压改色处理实验,并对处理前后的样品的紫外可见吸收光谱、红外吸收光谱以及光致发光光谱等谱学特征进行对比分析。结果表明:经高温高压改色处理后,钻石颜色由灰褐色变为褐黄色,钻石的紫外可见吸收光谱、红外吸收光谱和光致发光光谱也发生了很大改变。经处理的褐色钻石,其紫外可见吸收光谱中除原有的415nm和477nm吸收外,还产生503.2nm吸收,同时550nm至短波的吸收增强,钻石因此由原来的灰褐色变为褐黄色;红外吸收光谱中,1498、1520、1547cm~(-1)三个峰变为一个以1498cm~(-1)为中心的吸收宽峰;光致发光光谱中,产生了明显的H3(503.2nm)以及H2(986.2nm)缺陷。本研究获得的光谱变化特征为准确鉴定高温高压改色处理的Cape型钻石提供了依据,也为更好地理解晶格中氮、氢等相关的格子缺陷在高温高压条件下的变化机理提供了实验数据和分析。  相似文献   

非洲东南侧海域春季的几种危险天气系统   总被引：1，自引：1，他引：0  

李庆  马卫民  张学礼 《海洋预报》2006,23(4):88-94

本文利用执行任务累积的气象资料、NCEP和NWW3海浪模式资料,对非洲大陆东南侧海域春季的几种危险天气系统及其造成的大浪区进行了分析,初步揭示了这些危险天气系统的成因及其发展和变化规律。  相似文献   

Everyday human (in)securities in protected urban nature – Collaborative conservation at Macassar/Wolfgat dunes nature reserves,Cape Town,South Africa     

《Geoforum》2015

The diverse residents of the urban global South experience insecurities in everyday, immediate and subjective ways. Lemanski argues these insecurities relate not only to physical concerns like fear, crime, and violence but also to stressors like insecure tenure and financial situations, and threatened and contested lifestyles and cultures as cities rapidly change. This paper considers how diverse ‘everyday human (in)securities’ manifest through urban nature and shape collaborations around nature conservation. The focus is on protected coastal dunes in Cape Town and collaborative conservation participants, including municipal nature conservators and community representatives from the adjacent apartheid-era ‘townships’. The diverse ‘everyday human (in)securities’ perceived and experienced by these participants manifest variously in physical threats to bodies and biodiversity, but also in relation to the insecure tenure and financial situations experienced by residents and conservators alike, alongside differing cultural values of nature. Through attention to diffuse power relations and everyday experiences, divergent perceptions of (in)security are shown to be frictional and sometimes paradoxical in nature. Yet identifying these (in)securities also holds potential for exploring hopeful and productive negotiations around what ‘security’ might mean, and how it might be realised through the collaborations – bringing into dialogue contested spaces of urban nature in cities of the global South and North.  相似文献