排序方式： 共有27条查询结果，搜索用时 546 毫秒
1.
Managing sustainable farmed landscape through 'alternative' food networks: a case study from Italy 总被引：1，自引：0，他引：1
LEWIS HOLLOWAY ROSIE COX† LAURA VENN‡ MOYA KNEAFSEY‡ ELIZABETH DOWLER§ HELENA TUOMAINEN§ 《The Geographical journal》2006,172(3):219-229
This paper focuses on a case study of an 'alternative' food network based in the Abruzzo National Park, Italy, to explore how ideas of sustainable farmland management can be expressed through broader understandings of developing networks of care concerned with local economies and societies, high-quality specialist food products, particular 'traditional' farming practices and livestock breeds, as well as the ecology of a farmed landscape. The scheme allows customers, internationally as well as in Italy, to 'adopt' a milking sheep on a large mountain farm. In return, adopters are sent food products from the farm. The adoption scheme is inter-twined with an agri-tourism project which provides accommodation, runs a restaurant and engages in educational activities. The scheme is the result of the individual initiative of its founder, and is associated with a strongly expressed ethical position concerning the value of sustaining valued local rural landscapes and lifestyles, and the importance of 'reconnecting' urban dwellers with rural areas, farming and 'quality' food production. Yet the localness of the scheme is sustained through wider national and international networks: volunteer and paid workers are drawn from several European countries, funding has been acquired from the EU LEADER programme, and internet and transport technologies are essential in connecting with and supplying an international customer base. The broader economy of care instanced in this case study draws attention to a need to develop strategies for sustainable farmland management constructed around wider programmes of social, economic and cultural, as well as environmental, concern. 相似文献
2.
A computer program(FEA)is presented for processing historical laboratory data.It performs on a list ofsample entries stored in a laboratory information management system.Using an algorithm which is basedon fuzzy set theory,FEA classifies the entries into a limited number of clusters called sample types.Theclassification is fully user-defined.The program transforms the historical data into a representation whichis more suitable for studying the performance of the laboratory or which can be used as preparation for asimulation project. 相似文献
3.
4.
Basalts Generated by Decompressive Adiabatic Melting of a Mantle Plume: a Case Study from the Isle of Skye, NW Scotland 总被引：17，自引：13，他引：4
The primitive lavas of the Skye Main Lava Series (SMLS) arebasaltic rocks ranging from ne- to hy-normative, and definedas having MgO>7%. They have evolved by olivine(plus minorCr-spinel) fractionation from more picritic parental materialAn artificial data-set has been generated by normalizing allcompositions to 15% MgO by fractional addition of olivine, todefine compositional characteristics of primary magmas. Themost striking feature of the data-set is a very strong negativecorrelation between Si and Fe, as is seen in many oceanic alkalibasalt suites and in localized data-sets from mid-ocean ridgeswhen normalized for fractional crystallization. The SMLS dataare comparable to the compositions of equilibrium melts producedexperimentally by Hirose & Kushiro (Earth and PlanetaryScience Letters, 114, 477–489, 1993) from the relativelySi- and Fe-rich starting composition HK-66. Estimates of depthsand temperatures of last equilibration of the SMLS magmas withtheir mantle source have been made, on the assumption that mantlemelting may have been an equilibrium process. On this basis,it appears that primary magmas, containing 13–15% MgO,were generated by decompressive melting of abnormally hot mantle(estimated minimum mantle potential temperature, TP 1440C),associated with the Iceland plume. Melting was initiated inthe garnet stability field, and segregation is estimated tohave taken place over the pressure range 18–36 kbar (60–112-kmdepth) and a temperature range of 1390–1510 C. The P–Ttrajectory of segregation appears to coincide closely with estimatesof the solid + liquid adiabatfor mantle melting. Alkali basaltswere segregated from the greatest depths and olivine tholeiitesfrom higher levels, though the majority of magmas were derivedfrom near the top of the melting column. After segregation,magmas ascended to the surface, cooling at the rate of 3C/km,and were erupted in a comparatively narrow temperature rangeclose to 1200C. The suitability of HK-66 as a general modelfor mantle composition in ascending plumes is discussed, asmost within-plate primitive basalts in oceanic environmentsshare the same Fe-rich character as the SMLS, in which theycontrast with normal ridge-related magmas. Within-plate plumesmay perhaps tap mantle of abnormally high Fe/Mg, though thepossibility that compositional differences in plume-relatedand normal ridge-related magmas are generated by contrasts inprocess cannot yet be excluded. If, however, a relatively Fe-richreservoir exists deep within the mantle, and acts as the sourcefor plume-related magmatism, then ultimately a global positivecorrelation should exist between estimates ofTp and the Fe/Mgratio of the sources for individual suites.
Corresponding author 相似文献
5.
The Habit of Apatite in Synthetic Systems and Igneous Rocks 总被引：36，自引：2，他引：36
Apatite crystals co-existing with liquid or with vapour in thesystem CaO-CaF2-P2O6-H2O-CO2 are equant whereas those precipitatedfrom a liquid during a quench are greatly elongated parallelto the c-axis and they exhibit skeletal forms. Basic rocks inthe Karroo volcanic succession of Southern Rhodesia containapatite crystals with forms very similar to the synthetic quenchapatites. Acicular apatite crystals may prove to be of valueas a criterion for the former existence of a liquid phase inrocks whose origin is debatable. 相似文献
6.
The petrography of the olivine-rich basaltic rocks forming thelower part of the Karroo basalt sequence in the Nuanetsi provinceis briefly reviewed. These rocks contain phenocrysts of olivine,microphenocrysts of clinopyroxene, and phenocrysts of orthopyroxenejacketed by clinopyroxene. Mineral analyses and bulk rock analysesare presented and lead to the conclusion that most of the olivineand all of the clinopyroxene crystallized at low pressures shortlybefore solidification of the lavas. The orthopyroxene and someof the olivine, however, crystallized at a higher pressure andequilibria involving these phases controlled the bulk compositionsof the liquids. The results of experimental determinations ofphase relations of selected samples at 7 and 10 kb are reportedand suggest that equilibration with olivine and orthopyroxenetook place through a pressure range of approximately 6–12kb (18–36 km depth). It is possible that the process involvedwas one of polybaric crystal-fractionation but it is perhapsmore likely that equilibration of liquids with excess harzburgitewall-rock over the same pressure range accounts for the trendof bulk compositions. If this is so, a wedge of upper mantleperidotite must have penetrated through the continental crustto within 18 km (or less) of the surface. In view of the positionof the province on the line along which Gondwanaland underwentits first profound disruption, this conclusion is plausibleon general tectonic grounds. 相似文献
7.
Fluid infiltration and volume change during mid-crustal mylonitization of Proterozoic granite, King Island, Tasmania 总被引：2，自引：1，他引：1
The development of 10–30 m wide mylonite zones at mid-crustal depths in late Proterozoic granitoids on King Island, Tasmania, was associated with pervasive infiltration of low δ18 O-fluids (+5 to +7) on the scale of the shear zones. Syndeformational fluid–rock interaction produced substantial differences in mineral composition and bulk rock chemistry among several adjacent shear zones which are hosted by the same granite. In a shear zone at Cape Wickham with a normal slip component, changes in whole-rock chemistry between granite and mylonites indicate a gain of Ca, and losses of K and Na during deformation, which was nearly isovolumetric. Notable losses of K, Rb and Si occurred during partial retrograde alteration of mylonites near the western margin of this shear zone. The alteration suggests a component of up-temperature fluid flow. In contrast, 3 km to the south east, in a strike-slip shear zone at Disappointment Bay, complete albitization of plagioclase was associated with Na-gain and Ca-loss. Deformation also involved losses of Mg and Fe. Up to 60% volume gain occurred during the formation of closely spaced mesoscopic to microscopic quartz veins during mylonitization. The substantial silica-gain in this, as well as in two mylonite zones further south east, is interpreted to have been associated with upward flow of aqueous fluids along these shear zones. On the basis of a gradient reaction model, minimum time-integrated fluid-fluxes of 106 m3 /m2 are estimated for the Disappointment Bay (West) Shear Zone. 相似文献
8.
Wayne Arter† 《地球物理与天体物理流体动力学》2013,107(4):259-292
Abstract Nonlinear two-dimensional magnetoconvection, with a Boussinesq fluid driven across the field-lines, is taken as a model for giant-cell convection in the sun and late-type stars. A series of numerical experiments shows the sensitivity of the horizontal scale of convection to the applied field and to the Rayleigh number R. Overstable oscillations occur in cells as broad as they are deep, but increasing R leads to steady motions of much greater wavelength. Purely geometrical effects can cause oscillation: this work implies that strong horizontal field will in general lead to time-dependent convection. 相似文献
9.
10.
Geological structure of the active foreland fold and thrust belt of Papua New Guinea has been interpreted using high-quality seismic-reflection data. Three en échelon anticlines, the Strickland, Cecilia and Wai Asi, are located along the frontal margin of the Papuan Fold Belt. All three are foreland-vergent and cut by hinterland-dipping thrust faults that sole into a common detachment beneath the Oligocene to Miocene Darai Limestone. Two of the anticlines are linked by a right-lateral transfer zone. Folding occurs primarily in the upper 2000 m of strata, which consist of Darai Limestone overlain by Miocene to Quaternary siliciclastic sedimentary rocks. Beneath the Darai Limestone lies the less-competent shaly Ieru Formation, which exhibits disharmonic folding and variable bed thickness. Seismic-reflection data clearly show that the Plio-Pleistocene upper Era Beds are deformed to the same extent as the underlying Darai Limestone, demonstrating that most of the observed deformation has occurred during the Late Pliocene and Pleistocene. 相似文献