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1.
Israel's quest for security on its northern border with Lebanon has a history dating back to the foundation of the Palestine mandate. In the early period from the First World War to the end of the 1960s the quest was dominated with attaining economic and environmental security by seeking to acquire rights to the waters of South Lebanon. Recent decades in contrast have witnessed the rise in importance of border security and strategic security requirements in the face of military threats to northern Israel. Israel's interventionist policy in South Lebanon has been formalised to include a permanent presence on Lebanese territory in the form of the security zone. It is argued that despite the positive events that have occurred in the region in the early 1990s, it remains unlikely that Israel will easily relinquish its security shield in South Lebanon thus ultimately undermining the possibility of moving away from elusive to permanent security.  相似文献   

2.
The paper seeks to understand the Maltese food system in the context of its history and its geographical position within a broad Mediterranean setting of food production, processing, marketing and consumption. Although it has characteristics in common with Spain, Italy and Greece, Malta has some unusual features derived from its colonial heritage and its long-standing dependence upon imported foodstuffs. The future is uncertain because full membership of the European Union might threaten agricultural prosperity and indigenous food manufacturing. A systems of provision approach to the study of the Maltese food system would be an appropriate framework for further research.  相似文献   

3.
A method for calculating the most probable microsymmetry of the crystal field around the Kramers ion neodymium (III) in seven different host crystals is presented. The starting data are taken from carefully interpreted optical spectra available in the literature, no further information being necessary. Firstly the crystal field parameters for various assumed test symmetries are chosen to give the best fit to the splitting of the ground state multiplet, then a truncated crystal field calculation involving only a limited number of Stark levels is performed and suggestions for the microsymmetry are given in terms of the standard deviation between the calculated and experimental Stark splittings. It must be emphasized that all the calculations can be done with a standard personal computer.Paper from the NATO Advanced Study Institute on Physical Properties and thermodynamic Behaviour of Minerals, Cambridge 1987  相似文献   

4.
Anton Gosar 《GeoJournal》2000,52(2):107-117
Europe in general is in a great state of change. States uniting with difficulty, states collapsing in pain, newly freed states struggling for new political, economic, and social identities - it is a region in a true transition. The paper is focussing primarily on the European Shatter Belt, formerly known as Eastern Europe. This is in fact a subset of new and old nation-states in the region of Central and Eastern Europe or, to use an older, but increasingly popular term, Mitteleuropa (Ruppert, 1997). Mitteleuropa is reemerging from the commotion resulting from the collapse of the old political order - communism. Our focus in this presentation is on personal experiences and observations. We will note the progress and positive dimensions of the change (transition) in the light of Europe's and NATO expansion. We will address the issues at two scales- at the international/national level and then, at the level of a Slovenian case study. This will enable us to discuss the natural system of the process of enlargement and incorporate supporting material of geographical, historical and social nature as envisioned by Hartshorne. Since the collapse of communism, the region has experienced some serious traumas that vary in intensity across the region. Probably the greatest pain has been experienced in the former Yugoslavia - an estimated 150,000 have perished and about 2.5 millions have been displaced within and outside the country. Chaos still exists despite the protectorate arrangement in Bosnia. The hot spot Kosovo has yet to be calmed down. In parts of the region economic pain has been considerable. Every state of Mitteleuropa experienced absolute economic decline from 1990–1995; high inflation rates, increased economic inequality, high levels of poverty, increase of crime and more. Economic and psychological stress effect demographic processes. Things have partly changed to the better in the most recent years. The adoption of capitalism and a democratic political system has been painful, disorienting, and is still in progress. The democratization process varies considerably across the region and in some states is in jeopardy. Reformed communist parties had staged a restoration in nearly all of the states - in some winning the control of the government, in others gaining strong and influential positions, or both. But, two major processes promise future democracy, rule of law, wealth and stability in general. This is the decision of the member states of the European Union and NATO to incorporate some/several states of the Shatter Belt into their own zone of protection and/or federation. Nation-states of the region tend to follow the EU Agenda 2000 rules with Slovenia one of the first!  相似文献   

5.
Dominic Fenech 《GeoJournal》1997,41(2):153-163
For a small country whose main relevance to the outside world has always been its strategic location and whose known history has been moulded by that fact, security has been remarkably low on the list of priorities on Maltas national agenda since independence. In recent years, security has become an issue of keen political debate, although security per se may not be the real reason why the subject has been brought out into the limelight by both government and opposition. More than just an issue in its own right, security began featuring rather more as a function of the main direction of Maltas foreign policy, which during the past decade has been focused on relations with the European Union.  相似文献   

6.
This article focuses on post-1945 land-use development in the Sudetenland region. The wider historical and political consequences are discussed in the beginning as well as the methodical tools used in long-term land-use research in the Czech Republic so far. The important cleavage between borderland and inland is shown in regard to the different land use and land exploitation. Different parts of the borderland are examined in closer detail and the dissimilarity between areas in the western frontier and Northern Bohemia is explained, including the iron curtain effect.  相似文献   

7.
The effect of pH on the kinetics of smectite (K-montmorillonite) dissolution was investigated at 50 and 70 °C in stirred flow-through reactors over the pH range of 1-13.5. Experiments done at very acidic and very basic pH were far from equilibrium. Near neutral pH experiments were closer to equilibrium. The Al/Si release ratio, while initially being incongruent, ultimately approached the stoichiometric value in most of the experiments. Temperature, extreme pH, and time favor congruency. Rates can be described by:
  相似文献   

8.
Two South African coals of the same rank and age, but different in maceral composition were subjected to extensive structural analyses. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were studied to determine structural differences and similarities. The two coals had similar carbon content ( 84%, dmmf) and vitrinite reflectance (mean-maximum 0.71% for vitrinite-rich vs. 0.75% for inertinite-rich), but differed in hydrogen content (6.23% for vitrinite-rich and 4.53% for inertinite-rich). The inertinite-rich coal was more aromatic (86% for inertinite-rich and 76% for vitrinite-rich) and more polycondensed (indicated by a higher bridgehead carbon content). The inertinite-rich coal was structurally more ordered, with a higher degree of crystalline stacking. Both coals had similar average aromatic cluster sizes (16 carbons for vitrinite-rich and 18 carbons for inertinite-rich) and number of cluster attachments (6 attachments for vitrinite-rich and 5 attachments for inertinite-rich). Mass spectrometry showed that both coals consist of similar molecular weight distributions; ranging to approximately 1700 m/z with a maximum abundance of  450 m/z for the vitrinite-rich coal and  550 m/z for the inertinite-rich coal. Compared to the Argonne Premium coals the South African vitrinite-rich Waterberg coal was comparable to the coals in the high-volatile bituminous range and inertinite-rich Highveld was closer to the medium- to low-volatile bituminous range. Both coals were surprisingly similar in bulk characterization, although inertinite-rich Highveld coal was structurally more ordered, hydrogen deficient, and more aromatic.  相似文献   

9.
Terry Cannon 《GeoJournal》1995,35(2):137-150
Three issues related to hunger, famine and food security are highlighted by the problems faced by indigenous peoples in many parts of the world. They affect not only the indigenous groups themselves, but also the potential for improved and increased food availability for the rest of humankind. First, indigenous peoples themselves continue to be subjected to the shock impact of outsiders in ways that remove their traditional access to land and other resources, especially those that provide customary sources of foods. The shock is therefore very negative in nutritional as well as the better-known cultural and health terms. Second, the destruction and disruption of many indigenous peoples is reducing the pool of knowledge (ethnoschience) available concerning the biosphere and natural resources, which is of widespread value to humanity. Thirdly, this compounds the already well-known shock impact of the invaders on those natural resources through environmental destruction and habitat alteration. These issues have a potential impact on global sustainability that is far greater than might be suggested by the small numbers of indigenous peoples involved. The paper argues for priority to be given to the links between hunger and food problems, the human rights of indigenous peoples, and environmental destruction.An earlier verison of this paper was published in Hans-Georg Bohle (ed.).World of Pain and Hunger: geographical perspectives on famine and food security. Saarbrücken/Fort Lauderdale: Breitenbach Publishers, Freiburg Series in Development Studies, 1 (1994)I would like to acknowledge the support of the ESRC (UK), the IGU, the University of Greenwich, and the Henry R. Luce Food Programme at Hampshire College (USA) for enabling me to attend the IGU Workshop at which this was presented. This paper has benefitted from the helpful criticisms of members of that workshop, and of other colleagues in Britain and The Netherlands; I remain responsible for its opinions and any errors.  相似文献   

10.
A finite element model is used to generate theoretical excess210Pb concentration/depth profiles that are best-fit approximations to directly measured profiles at five locations in western Lake Ontario. The best-fit approximations are derived using a minimum error analysis technique. The results indicate that, while mixing is prevalent at all the study locations, its influence is severe at locations closer to the mouth of the Niagara River. The nonoccurrence of the implicit effects of sediment mixing in measured pollutant profiles at these locations is pointed out and it is postulated that the general assumptions of constant flux of excess210Pb and constant sedimentation rate in such models lead to unrealistic estimates of mixing.  相似文献   

11.
The mica-like layer compound KNiAsO4 easily exchanges its interlayer potassium ions for alkyl ammonium ions, RNH 3 + (R=CH3 - C18H37). Short chain ions (<>4) will react in aqueous solution and longer chains in ethanolic solution. The reaction of KNiAsO4 with aqueous solutions of methyl, ethyl and butyl ammonium chlorides of different concentrations has been investigated using a potassium ionselective electrode. Room temperature kinetic curves of percent exchange vs time were obtained. These indicate an apparent cooperative mechanism with some rearrangement of the alkyl ammonium ions between the layers during the reaction. KNiAsO4 also reacts with water. This reaction may facilitate the exchange reaction with aqueous alkyl ammonium ions. The alkyl ammonium ions form ordered arrangements between the [NiAsO4] layers. Small chains (<>4) adopt a variety of configurations within the same product.Paper from the NATO Advanced Study Institute on Physical Properties and Thermodynamic Behaviour of Minerals, Cambridge 1987  相似文献   

12.
This paper explores the environmental conditions that faced the people of ancient Jawa during the Holocene, as well as previous prehistoric periods of the mid-late Pleistocene. Calcite speleothems in a lava tube are dated using the U-Th method, to marine oxygen isotope stage 7 from  250 to 240 ka and from  230 to  220 ka; and the stage 5/4 transition between  80 and 70 ka. The available evidence indicates general aridity of the Black Desert during most of the mid-late Quaternary, punctuated by short wetter periods, when the Mediterranean cyclonic systems intensified and penetrated the north Arabian Desert. These Mediterranean systems had a longer and more intense effect on the desert fringe closer to the Mediterranean and only rarely penetrated the Black Desert of Jawa. The results do not exclude some increase of rainfall which did not change water availability dramatically during the warm Holocene. The ancient Jawa city appears to have depended on technological ability to build elaborate runoff-collection systems, which became the prime condition for success.  相似文献   

13.
Summary Propellant embedded anchors can be used to secure offshore platforms by rapidly anchoring them in seafloor rock. Field tests conducted by the U.S. Navy showed inconsistent results. A more promising approach seems to be modelling of anchor penetration and pullout resistance in jointed rock based on first principles.In this paper, physical model tests are described with which the physical phenomena are investigated and which will serve as a basis for predictive analytical models. The laboratory experiments, conducted with fasteners to model the anchors and with jointed and intact rock models made from gypsum, showed that basic intact material properties, joint configuration and individual joint properties influence penetration and pullout resistance. If the behavior is brittle, penetration is accompanied by cracking, otherwise ductile continuum deformation occurs. Jointing affects cracking in that closer joint spacing restricts cracking to fewer joint bounded plates but increases the number of cracks in the individual plate. The increased cracking intensity leads to a reduced pullout resistance.For purposes of analytical modelling, one can therefore, in a first step, build upon established relations between intact meterial, joint geometry and individual joint characteristics.  相似文献   

14.
The present paper deals with the specification of bed erosion flux that accounts for the effects of sediment-induced stratification in the water column. Owing to difficulties in measuring the bed shear stress b and the erosive shear strength s, we suggest a series of methods that combine laboratory and numerical experiments. A simplified turbulent transport model that includes these effects helps to quantify b and s. Focusing on soft stratified beds, the present study considers erosion rate formulas of the form =f exp {[Tb-Ts]} where is a model constant (=1 for Gularte's (1978) formula and =1/2 for Parchure's (1984) formula). First, the bed erosive strength profile s(Z) is adjusted by forcing the turbulent transport model with measured erosion rates. Second, three procedures are suggested to determine the erosion rate formula coefficients f and : a global procedure and two different layer-by-layer procedures. Each procedure is applied to an erosion experiment conducted in a rotating annular flume by Villaret and Paulic (1986). The use of the layer-by-layer procedure based on a least squares fitting technique provides a closer fit than the global procedure. The present study points out the complementarity of experimental and numerical approaches and also suggests possible improvements in laboratory test procedures.  相似文献   

15.
The N–S oriented Coastal Cordillera of South Central Chile shows marked lithological contrasts along strike at 38°S. Here, the sinistral NW–SE-striking Lanalhue Fault Zone (nomen novum) juxtaposes Permo-Carboniferous magmatic arc granitoids and associated, frontally accreted metasediments (Eastern Series) in the northeast with a Late Carboniferous to Triassic basal-accretionary forearc wedge complex (Western Series) in the southwest. The fault is interpreted as an initially ductile deformation zone with divergent character, located in the eastern flank of the basally growing, upwarping, and exhuming Western Series. It was later transformed and reactivated as a semiductile to brittle sinistral transform fault. Rb–Sr data and fluid inclusion studies of late-stage fault-related mineralizations revealed Early Permian ages between 280 and 270 Ma for fault activity, with subsequent minor erosion. Regionally, crystallization of arc intrusives and related metamorphism occurred between 306 and 286 Ma, preceded by early increments of convergence-related deformation. Basal Western Series accretion started at >290 Ma and lasted to 250 Ma. North of the Lanalhue fault, Late Paleozoic magmatic arc granitoids are nearly 100 km closer to the present day Andean trench than further south. We hypothesize that this marked difference in paleo-forearc width is due to an Early Permian period of subduction erosion north of 38°S, contrasting with ongoing accretion further south, which kinematically triggered the evolution of the Lanalhue Fault Zone. Permo-Triassic margin segmentation was due to differential forearc accretion and denudation characteristics, and is now expressed in contrasting lithologies and metamorphic signatures in todays Andean forearc region north and south of the Lanalhue Fault Zone.  相似文献   

16.
Optically visible Albite glide twins in a peristerite (An9Or1.6), identified from their tapering shape and relationship to grain boundaries, were studied by transmission electron microscopy. Near the tips in sections a, the microstructure consists of small (400 nm long) lensshaped Albite twins centred exclusively on the oligoclase lamellae. The lenses extend partly outwards into the two adjacent low albite lamellae and induce strong inhomogeneous strain. Where the lenses are closer together, they form, depending on the sense of shear, nearly linear left or right-stepping en échelon arrays, with overlap of the strain fields. Slightly farther in from the tip, the twin domains coalesce to form continuous pinch-and-swell lamellae, being always thicker in the oligoclase. Because of Si,Al order, only elastic glide pseudotwins are possible in low albite. In oligoclase glide pseudotwins may be mechanically stable (metastable relative to Si,Al order) and may deviate only slightly from true twins. Pseudotwins develop first in the oligoclase, propagate dynamically by jumping across the intervening albite lamellae, extend lengthways and thicken sideways and finally coalesce. They are stabilized by diffusion-controlled inversion of Si,Al order giving rise to true twins described in a companion paper.C.R.P.G. contribution 799  相似文献   

17.
Alkali olivine basalts from Skye were simultaneously contact metamorphosed by Tertiary gabbro and granite intrusions and altered by the hydrothermal convection system that the plutons induced. Four metamorphic zones were mapped around the plutons. Furthest from the intrusions, in the primary olivine zone, metabasalts are composed of combinations of igneous olivine, augite, plagioclase, titaniferous magnetite, ilmenite, zeolites, gyrolite, sulfides, and chlorite-smectite intergrowths. Closer to the plutons, in the smectite zone, saponite and carbonate appear, primary olivine and gyrolite disappear, and zeolites decrease dramatically in abundance. Still closer to the plutons, in the amphibole zone, actinolite, edenite, chlorite, sphene, epidote, andradite, and quartz appear and saponite and chlorite-smectite intergrowths disappear. Along parts of the contact between gabbro and basalt, in the orthopyroxeneolivine zone, orthopyroxene, metamorphic olivine, and biotite appear and amphibole, chlorite, sphene, epidote, andradite, carbonate, and quartz disappear. Whole-rock chemical data indicate only minor change in the major-element chemical composition of the metabasalts during progressive metamorphism/hydrothermal alteration. Two-pyroxene eothermometry and various mineral-fluid equilibria suggest the range of peak temperatures attained in the metamorphic zones: orthopyroxene-olivine zone, 900°1, 030° C; amphibole zone, 400°–900° C; smectite and primary olivine zones, < 400° C. Mineralogical and oxygen isotopic alteration of the metabasalts were closely coupled: Basalts from the primary olivine zone with nearly unaltered igneous mineralogies have normal or near-normal wholerock 18O>+5 (SMOW); mineralogically more altered basalts from the smectite zone have whole-rock 18O=+2 to +5; still more mineralogically altered basalts from the amphibole zone (with one exception) have 18O<+ 2; completely recrystallized hornfelses from the orthopyroxene-olivine zone have 18O<0. The principal mechanism of isotope exchange between basalt and metamorphic/ hydrothermal fluid probably was heterogeneous mineralfluid reaction.Metabasalts from the orthopyroxene-olivine zone are mineralogically fresh pyroxene hornfelses that record crystallization temperatures > 1,000° C yet have highly altered whole-rock oxygen isotope compositions, 18O<0%. The hornfelses chemically interacted with metamorphic/hydrothermal fluids either at very high temperatures or while they were heated to > 1,000° C or both. Their mineralogy, however, rules out significant water-rock interaction after they cooled below 900° C. Hydrothermal convection on Skye was a two-stage process: (a) fluid flow through wall rocks initially was pervasive while they are heated; (b) fluid flow after the thermal peak in the wall rocks was sufficiently channelized that rocks such as those in the orthopyroxeneolivine zone were isolated from further fluid-rock interaction during all or almost all of the cooling history of the hydrothermal system.  相似文献   

18.
High-resolution electron microscopy of an intermediate microcline (Or93) from a granodiorite in southeastern Australia reveals anen echelon arrangement of triclinic lens-shaped domains, twinned on the albite law. The domains are tabular on (010), are only a few unit cells wide, but extend 20 or 30 unit cells alongx, until they merge into a zone of monoclinic cells roughly aligned in the rhombic section. The domains are longer and less clearly terminated alongz. Strain calculations show that the energy released by Al/Si ordering, producing the orthoclase-microcline inversion, is equal to the strain energy developed when triclinic domains are forced to retain the original monoclinic crystal shape. This balance of strain energies thus explains the metastable persistence of intermediate microcline into the region of maximum microcline stability. Shearing along faults during deformation of the granodiorite released the strain in some of these feldspars, allowing maximum microcline to develop, and so giving rise to a bimodal distribution of triclinicities throughout the pluton. The value of measured for the intermediate microcline is the average of a range of values throughout each domain, and may be considerably closer to 90° than from an unstrained crystal with the same degree of Al/Si order.  相似文献   

19.
Late Cretaceous, granitic pegmatite-aplite dikes in southern California have been known for gem-quality minerals and as a commercial source of lithium. Minerals, whole-rock samples, and inclusion fluids from nine of these dikes and from associated wall rocks have been analyzed for their oxygen, hydrogen, and carbon isotope compositions to ascertain the origins and thermal histories of the dikes. Oxygen isotope geothermometry used in combination with thermometric data from primary fluid inclusions enabled the determination of the pressure regime during crystallization.Two groups of dikes are evident from their oxygen isotope compositions (18Oqtz+10.5 in Group A, and +8.5 in Group B). Prior to the end of crystallization, Group A pegmatites had already extensively exchanged oxygen with their wall rocks, while Group B dikes may represent a closer approximation to the original isotopic composition of the pegmatite melts. Oxygen isotope fractionations between minerals are similar in all dikes and indicate that the pegmatites were emplaced at temperatures of about 730 ° to 700 ° C. Supersolidus crystallization began with the basal aplite zone and ended with formation of quench aplite in the pocket zone, nearly to 565 ° C. Subsolidus formation of gem-bearing pockets took place over a relatively narrow temperature range of about 40 ° C (approximately 565–525 ° C). Nearly closed-system crystallization is indicated.Hornblende in gabbroic and noritic wall rocks (Dw.r. = –90 to –130) in the Mesa Grande district crystallized in the presence of, or exchanged hydrogen with, meteoric water (D –90) prior to the emplacement of the pegmatite dikes. Magmatic water was subsequently added to the wall rocks adjacent to the pegmatites.Groups A and B pegmatites cannot be distinguished on the basis of their hydrogen isotope compositions. A decrease in D of muscovite inward from the walls of the dikes reflects a decrease in temperature. D values of H2O from fluid inclusions are: –50 to –73 (aplite and pegmatite zones); –62 to –75 (pocket quartz: Tourmaline Queen and Stewart dikes); and –50 ± 4 (pocket quartz from many dikes). The average 13C of juvenile CO2 in fluid inclusions in Group B pegmatites is –7.9. In Group A pegmatities, 13C of CO2 is more negative (–10 to –15.6), due to exchange of C with wall rocks and/or loss of 13C-enriched CO2 to an exsolving vapor phase.Pressures during crystallization of the pockets were on the order of 2,100 bars, and may have increased slightly during pocket growth. A depth of formation of at least 6.8 km (sp. gr. of over burden = 3.0, and P fiuid=P load) is indicated, and a rate of uplift of 0.07 cm/yr. follows from available geochronologic data.  相似文献   

20.
The Mo stable isotope system is being applied to study changes in ocean redox. Such applications implicitly assume that Mo isotope fractionation in aqueous systems is relatively insensitive to frequently changing environmental variables such as temperature (T) and ionic strength (I). A major driver of fractionation is the adsorption of Mo to Mn oxyhydroxide surfaces [Barling J. and Anbar A. D. (2004) Molybdenum isotope fractionation during adsorption by manganese oxides. Earth Planet. Sci. Lett.217(3-4), 315-329]. Here, we report the results of experiments that determine the extent to which Mo isotope fractionation during adsorption of Mo to the Mn oxyhydroxide mineral birnessite is sensitive to T and I. The results are compared to new predictions from quantum chemical computations. We measured fractionation from 1 to 50 °C at I = 0.1 m and found that Δ97/95Modissolved-adsorbed varies from 1.9‰ to 1.6‰ over this temperature range. Experiments were also performed at 25 °C in synthetic seawater (I = 0.7); fractionation at this condition was the same within analytical error as in low ionic strength experiments. These findings confirm that the Mo isotope fractionation during adsorption to Mn oxyhydroxides is relatively insensitive to variations and T and I over environmentally relevant ranges. To relate these findings to potential mechanisms of Mo isotope fractionation, we also report results for density functional theory computations of the fractionation between and various possible structures of molybdic acid as a function of temperature. Because no plausible species fractionates from with a magnitude matching the experiments, we are left with three possibilities to explain the fractionation: (1) solvation effects on the vibrational frequencies of aqueous species considered thus far are significant, such that our calculations in vacuo yield inaccurate fractionations; (2) a trace aqueous species not yet considered fractionates from and then adsorbs to birnessite; or (3) a surface complex not present in solution forms on birnessite in which Mo is not tetrahedrally coordinated. Our findings help validate assumptions underlying paleoceanographic applications of the Mo isotope system and also lead us closer to understanding the mechanism of isotope fractionation during adsorption of Mo to Mn oxyhydroxides.  相似文献   

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