Coesite micro-inclusions and the U/Pb age of zircons from the Hareidland Eclogite in the Western Gneiss Region of Norway     

D. A. Carswell  R. D. Tucker  P. J. O''Brien  T. E. Krogh 《Lithos》2003,67(3-4):181-190

We have identified by laser micro-Raman spectroscopy that inclusions of coesite occur together with other eclogite-facies mineral phases within metamorphic zircons separated from the large eclogite body at Ulsteinvik–Dimnøy on Hareidland. This is the first identification of coesite from this portion of the northwestern Western Gneiss Region (WGR) and supports continuity of ultrahigh-pressure (UHP) metamorphism between the documented coesite occurrences on Stadlandet to the south and the microdiamond and coesite pseudomorph localities on Fjørtoft in the Nordøyene to the north. The zircons, first analysed by U–Pb TIMS in 1973, have been re-analysed and have yielded a much more precise age of 401.6±1.6 Ma, that overlaps with the previously determined age. Our discovery of coesite and the indication of a close to 402 Ma formation age add to a growing number of mid–late Early Devonian ages that signal that the UHP metamorphism in this part of west Norway occurred relatively late in the Caledonian orogenic cycle. These observations should be incorporated in geodynamic models for the exhumation of these rocks and for the metastable preservation of eclogite-facies mineralogies.  相似文献   

The Role of non-timber forest products as safety-nets: A review of evidence with a focus on South Africa     

Fiona Paumgarten 《GeoJournal》2005,64(3):189-197

Poor, rural communities are vulnerable to adversity. To secure their livelihoods, people adopt multiple livelihood strategies, including using non-timber forest products (NTFPs). NTFPs have been identified as important to rural livelihoods, as an alternative land-use option as well as in fulfilling an important safety-net function although empirical evidence on the latter’s strength is limited. Whilst NTFPs may contribute towards alleviating poverty, this safety-net function needs more critical and quantitative investigation. This includes the establishment of an applicable definition so this function can be communicated to policy makers and taken into account in national poverty alleviation strategies and, in attempts to promote resource-conserving behaviour by highlighting the value of natural resources (including NTFPs) compared to alternative land-use options. Poverty in rural households is complex and households are vulnerable to a range of shocks. During adversity households can turn to a range of possible safety-nets. What determines the use of NTFPs as a safety-net, how this safety-net function manifests and the strength of this function is poorly understood and there is need for further investigation.  相似文献   

Challenging a place myth: New Zealand's clean green image meets the biotechnology revolution     

Fiona Coyle  John Fairweather 《Area》2005,37(2):148-158

The 'clean green image' of New Zealand is a well-known example of what has been called a 'place myth'. But more recently, emerging alongside this place myth is an image that the government is trying to co-create of New Zealand as an innovator in biotechnology. In nationwide focus groups, whilst a matter of pride, participants typically saw this clean green myth as a temporally distant utopia. However, when considered alongside the futures proposed by biotechnology, clean green New Zealand was mobilized into the present moment to defend a general reluctance to take up these practices. Alternately, some participants saw the possibility for co-evolution of the place myths, with biotechnology enabling the re-construction of a 'picture-perfect', clean green country.  相似文献   

A first detailed look at the Greenland lithosphere and upper mantle, using Rayleigh wave tomography   总被引：2，自引：1，他引：2  

Fiona A. Darbyshire  Tine B. Larsen  Klaus Mosegaard  Trine Dahl-Jensen  Ólafur Gudmundsson  Torben Bach  Søren Gregersen  Helle A. Pedersen  Winfried Hanka 《Geophysical Journal International》2004,158(1):267-286

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A Polygenetic Landform At Stígá, Öræfajökull, Southern Iceland     

Tim Harris  Fiona S. Tweed  Óskar Knudsen 《Geografiska Annaler: Series A, Physical Geography》2004,86(2):143-154

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Climatic Control of Hydraulic Conductivity of Bahamian Limestones   总被引：1，自引：0，他引：1  

Fiona F. Whitaker  Peter L. Smart 《Ground water》1997,35(5):859-868

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Reconceptualising local community: environment, identity and threat   总被引：1，自引：0，他引：1  

Simon Dalby  Fiona Mackenzie 《Area》1997,29(2):99-108

Summary Economic 'development' driven by global economic forces produces specific expressions of 'community' in places where large new economic projects are to be located. This paper draws on contemporary geopolitical literature to theorise community identity as partly formulated in response to external 'threats'. A comparative study of community mobilisation in response to proposals to locate coastal superquarries on the Isle of Harris, Outer Hebrides, Scotland, and Cape Breton, Nova Scotia, Canada, suggests the applicability of this theoretical framework for extending geographical analysis of community identity and the politics of place.  相似文献   

Application of Bryozoan zoarial growth-form studies in facies analysis of non-tropical carbonate deposits in New Zealand     

Campbell S. Nelson  Fiona M. Hyden  Sandra L. Keane  William L. Leask  Dennis P. Gordon 《Sedimentary Geology》1988,60(1-4):301-322

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The metamorphic evolution of Mg---Cr type Norwegian garnet peridotites   总被引：6，自引：0，他引：6  

D.A. Carswell 《Lithos》1986,19(3-4):279-297

Mineralogical and microstructural data are presented which demonstrate that the garnet peridotites variably preserved in Alpine-type bodies within the Western Gneiss Region of Norway have had a prolonged, 7-stage, evolutionary history. High-temperature Al-pyroxene ± spinel protolith assemblages (ass. I) are only rarely preserved but predate the coarse-grained P_max garnet lherzolite assemblages (ass. II). Porphyroclastic textured samples demonstrate subsequent recrystallisation to a lower-pressure 5-phase garnet + spinel lherzolite assemblage (ass. III). Most samples show development of kelyphites of intimately intergrown replacement pyroxenes + spinel (ass. IV) around garnets. These are in turn frequently overgrown by late coarser-grained coronas of orthopyroxene + pargasittic amphibole + spinel (ass. V). The chrome-depleted secondary garnets are interpreted to have predated kelyphite formation contrary to most previous interpretations. Assemblages VI and VII reflect the late-stage stability at reduced temperatures of firstly aluminous chlorite and finally serpentine + talc assemblages.

As the peridotites may contain up to six generations of certain mineral phases (notably orthopyroxene) and individual grains are frequently compositionally zoned, considerable care has been exercised over the selection of mineral compositions appropriate to the various mineral equilibria used to deduce the overall P-T path followed by these rocks. Finally, general aspects of the origin and tectonic setting of these rocks and of the age of the various observed assemblages are discussed. Whilst the early assemblages (I and II) appear to be mid-Proterozoic in age, the later assemblages (III å VII) are probably all Caledonian).  相似文献   

Metamorphic an magmatic events in the Uweinat — Bir Safsaf Uplift (Western Desert/Egypt)     

Dr. Heinz Schandelmeier  Fiona Darbyshire 《International Journal of Earth Sciences》1984,73(2):819-831

The Uweinat — Bir Safsaf Uplift, Western Desert/Egypt, four episodes of deformation and related metamorphism and anatexis occurred until the final cratonisation during the Late Pan-African event was completed. From that time on, probably six independent (Table 4) magmatic episodes can be recognized up to the Quaternary. This anorogenic type of magmatism is mainly related to a fracture system which originated in the Late Precambrian as a result of intraplate block faulting. Periodical reactivation of these older fracture zones throughout the Phanerozoic gave way to the different types of plutonic and volcanic rock assemblages.

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Zusammenfassung Die Grundgebirgsschwelle zwischen Gebel Uweinat und Bir Safsaf (Western Desert/ Ägypten) war während des Präkambriums durch vier Episoden von Deformation, Metamorphose und Anatexis gekennzeichnet. Die endgültige Kratonisierung erfolgte im Jungproterozoikum im Verlauf eines Pan-Afrikanischen Thermalereignisses. Die während des Jungproterozoikums als Folge großräumiger Intraplattentektonik entstandenen Bruchsysteme wurden während des Phanerozoikums periodisch reaktiviert. Die Platznahme anorogener Magmen erfolgte in mindestens sechs verschiedenen Zeiträumen hauptsächlich entlang dieser Bruchstrukturen.

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Résumé Le massif soulevé compris entre le Gebel Uweinat et Bir Safsaf, dans le Désert occidental de l'Egypte, a été le siège de 4 épisodes de déformations avec métamorphisme et anatexie jusqu'à sa cratonisation finale au cours de la Phase Pan-africaine tardive. A partir de ce moment, probablement six épisodes magmatiques indépendants peuvent être reconnus jusqu'au Quaternaire. Ce type anorogénique de magmatisme est principalement en relation avec un système de fractures qui a pris naissance au Précambrien supérieur comme le résultat d'une régime de fracturation intraplaque. La réactivation périodique des ces zones de fractures anciennes durant le Phanérozoïque a conduit à la formation de ces différents types d'associations de roches volcaniques et plutoniques.

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