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1.
Police, politics, and the right to the city   总被引：1，自引：0，他引：1  
Mustafa Dikeç 《GeoJournal》2002,58(2-3):91-98
Space and spatiality have recently been at the core of debates concerning the political possibilities of the city. The arguments advanced in this paper might be seen as an attempt to contribute to these debates through a reflection on the spatiality of (in) justice, politics, and the right to the city. The case of French urban policy, with its focus on distressed urban areas, and the `suburban problem' in France are used as examples to make arguments more concrete.  相似文献   

2.
Average concentrations of Pb, Zn, Cu, and other metals, as well as S and As, were calculated for the Aue granitic cupola, the contact aureole of which hosts the large vein-type uranium deposit of Schlema-Alberoda and the Schneeberg uranium-base metal deposit (Erzgebirge, Germany). The cupola was exposed by mine workings and boreholes, which provided an opportunity to evaluate variations in the abundances of metals in the granites over a vertical interval of more than 2.5 km and estimate their losses in the upper oxidized part of the investigated volume of the cupola (coefficient of iron oxidation, KO Fe, increases in the granites from bottom to top from 7 to 70%) compared with the lower unaltered and unoxidized part (with a KO Fe plateau at about 5%). The average concentrations of metals in the upper part of the cupola are lower than those in the lower part by a factor of 2.5 for Pb, 1.56 for Zn, 1.45 for Cu, 1.3 for Co, etc. A similar decrease in the abundances of ore elements along the vertical section associating with the relative epigenetic alteration and oxidation of the granite was previously described by us for U and Th and for the components of high-temperature ores, W, Sn, and Mo. The removal of ore elements from the granite was accompanied by a decrease in the bulk contents of sulfur and arsenic by a factor of 1.35 and 1.65, respectively. The leaching of trace metals from the granites of the upper part of the Aue cupola was followed by their partial redeposition above the cupola in the ore veins of the Schlema and Schneeberg deposits. Original Russian Text ? Vikt. L. Barsukov, N.T. Sokolova, O.M. Ivanitskii, 2006, published in Geokhimiya, 2006, No. 9, pp. 967–982.  相似文献   

3.
The behavior of trace elements under conditions of partial melting of granitoid rocks has been studied. The element’s partition coefficients between minerals and the melt Dimin/melt depends, in the first place, on the composition of the primary melt. In biotite the HREE Di are a little below 1, while those of LREE, especially Di for Ce, are 1–3 orders of magnitude less. This leads to an efficient differentiation of REEs in anatexic melts especially when biotite is the main mineral phase of restite. On the contrary, there are feldspars, the Di of which cannot provide such a magnitude of differentiation. Unlike garnets and pyroxenes, whose stability in restite permits enrichment of anatexic melts produced in migmatization zones with Nb, Ti, and Cr, the presence of biotite in restite causes depletion of melts with those elements as well as with Rb. Feldspars, under conditions of their fractional crystallization or during differentiation of an anatexic melt, deplete the latter with Sr, Ba, and Rb, but enrich it with Nb, Ti, Cr, Y, Zr, and V.  相似文献   

4.
Mercury contamination in aquatic environments is of worldwide concern because of its high biomagnification factor in food chains and long-range transport. The rivers, estuary and the bay along the northwestern Bohai Sea coast, northeastern China have been heavily contaminated by Hg due to long-term Zn smelting and chlor-alkali production. This work investigated the distributions of total Hg (THg) and monomethylmercury (MMHg) in the water, sediment and hydrophytes from this area. Concentrations of THg in sediment (0.5–64 mg kg−1) and water (39–2700 ng L−1) were elevated by 1–3 orders of magnitude compared to background concentrations, which induced high concentrations of MMHg in these media. The highest concentration of MMHg in sediment reached 35 μg kg−1, which was comparable to that in the Hg mining area, Wanshan, China, and the highest MMHg concentration of 3.0 ng L−1 in the water sample exceeded the MMHg Chinese drinking water guideline of 1.0 ng L−1. Concentrations of THg in a sediment profile from Jinzhou Bay were found to be consistent with annual Hg emission flux from a local Zn smelter (r = 0.74, p < 0.01), indicating that Hg contamination was mainly caused by Zn smelting locally. For some freshwater hydrophytes, concentrations of THg and MMHg ranged from 5.2 to 100 μg kg−1 and 0.15 to 12 μg kg−1, respectively. Compared to sediment, concentrations of THg in hydrophytes were 2–3 orders of magnitude lower but MMHg was comparable or higher, indicating that the bioaccumulation in plants was distinct for the two Hg species studied. The data suggest that a significant load of Hg has been released into the northwestern coastal region of the Bohai Sea.  相似文献   

5.
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.  相似文献   

6.
Tony Waltham 《Geology Today》2010,26(4):152-158
Gigantic floods that, for just a few days, had flow rates many times greater than the combined flows of all the other rivers of the world put together. Sounds ridiculous, and it's almost inconceivable, but it's real, and it all happened at the end of the last Ice Age. The water came from Lake Missoula, which exists no more, but the effects are still to be seen in the landscapes, most notably in the vast scablands of eastern Washington.  相似文献   

7.
Yuriy Sokolov 《GeoJournal》1992,26(4):497-502
The discovery of a new continent that was later called America by Christopher Columbus some five hundred years ago, has in one way or another, influenced people the World over. The extraordinary significance of this event for mankind is displayed by the dimension of the consequences and the variety of reactions among nations and communities of the “Old World”.  相似文献   

8.
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9.
The 1988 good rainy season in the Sudan raised the hopes that desertification/land degradation and shortage of food so markedly observed in Western Sudan have been elevated. This was particularly so as large quantities of grains were produced in the mechanized rain-fed agricultural schemes in the clay plains of Eastern Sudan. But the field work carried by the author in the Umm Ruwaba district of Kordofan region in July/August 1989 shows that, although there has been some improvement in the crop production situation, desertification/land degradation and shortage of food produced locally are still prevailing in the district. The people are still living below the poverty line, but they are able to cope because of remittances from members of the families working abroad and because of donations of food by some world organizations.  相似文献   

10.
Based on the historical records of natural disasters and human wars of the final 35 years in the late Ming Dynasty (1610–1644 AD) obtained using different spatial scales, a set of grading systems were established to classify, grade and present these records and their spatiotemporal characteristics. From natural and human perspectives to quantitative analyses of the direct causes of the collapse of the Ming Dynasty, the author draws conclusion regarding a total of six immediate factors, which were, according to the rate of contribution from high to low, internal rebellions, drought, inter-ethnic conflicts, locust, flood and external wars. Among these causes, human factors accounted for approximately 47%, while natural factors accounted for approximately 53%. Attribution analysis indicated that the basin areas in east China were sensitive to climate change during the Ming Dynasty. Severe drought and locusts in a cooling environment were the main natural causes, while frequent internal rebellions and inter-ethnic conflicts influenced by financial crisis were the major human factors. Although natural factors accounted for a greater percentage than human factors in the rate of contribution to the collapse of the Ming Dynasty, they were the only external factors impacting social development and changes.  相似文献   

11.
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12.
Text, talk, things, and the subpolitics of performing place   总被引：1，自引：0，他引：1  
This article tells the story of how a group of Dutch and Belgian citizens organized themselves to promote an area that they valued, to put it on the map, to raise awareness about its qualities, and to protect it from urban and industrial development. Our theoretical perspective focuses on the performative and political aspects of this place-making process and the discursive and material practices involved. We connect this to Beck’s concept of subpolitics.Our findings show how the group performed this place not only through text and talk - giving the area a name, using their knowledge and expertise to raise awareness about its values, lobbying and cooperating with decision-makers -, but also through things - installing art objects and information signs that articulate certain characteristics and values of the area. Our findings demonstrate the struggles involved in these performances. The group involved multiple perspectives on what the important values and characteristics of the area are and on what strategies would work best in trying to influence decision-making and protect the area. However, the use of expertise as the main strategy to gain influence excluded the more critical and activist strategies and privileging archaeological and historical values and characteristics came at the expense of attention on agricultural and natural values.Our findings make clear that performing place cannot be taken to be homogeneous and that it inevitably involves multiple perspectives and demands. The struggles, power relations and dynamics of inclusion and exclusion that this multiplicity implicates reveal a form of sub-politics that involves both politicization and depoliticization. Also, it is a form of subpolitics that is more diverse and ambiguous than Beck’s conceptualization presupposes by its emphasis on the role of outsiders as a homogeneous group.  相似文献   

13.
The mineral composition of the Talatui gold deposit has been studied with modern methods. Previously unknown minerals (ilmenite, siegenite, glaucodot, wittichenite, matildite, hessite, pilsenite, zircon, tremolite, cummingtonite, hercynite, and goethite) have been identified in the ore. A high Re content has been detected in molybdenite. The spatiotemporal separation of Au and Ag is caused by different mineral species of these elements and their diachronous precipitation during the ore-forming process. Gold crystallized along with early mineral assemblages, beginning from virtually pure gold (the fineness is 996). Silver precipitated largely at the end of the process as hessite (Ag2Te) and matildite (AgBiS2). The temperature of ore deposition varied from 610 to 145°C, the pressure was 3370–110 bar, and the salt concentration ranged from 56.3 to 0.4 wt % NaCl equiv. The heterogeneous state (boiling) of fluid at the early stages has been documented. The chemical and isotopic compositions of the fluid testify to its magmatic nature and the participation of meteoric water at late stages in the ore-forming process. Thermodynamic modeling reproduces the main specific features of ore formation, including separation of Au and Ag. A physicochemical model of the gold mineralization in the Darasun ore district has been proposed. On the basis of several attributes, the Talatui deposit has been referred to the prophyry gold-copper economic type.  相似文献   

14.
For optimum bauxitisation conditions a relatively stable geomorphological history is essential. On the Gove and Mitchell Plateaux therefore, the adverse effects of land emergence and ensuing planation are counteracted by associated mild synclinal warping, so that the deposits constituted coastal hinge zones of at least two successive land (erosion) cycles. Nevertheless, following the main Cretaceous and Tertiary period of bauxitisation by leaching, the deposits were partially submerged by the sea and, particularly at Mitchell Plateau, extensively reworked. Assisted by quantitative heavy mineral studies distinct unconformities within several bauxite profiles can be established. Finally, the quantitative mineralogy of both deposits is discussed in some detail and an origin (supported by experimental studies) proposed.
Zusammenfassung Die beste Voraussetzung für eine optimale Bauxitisation ist geomorphologische Stabilität. Auf den Gove- und Mitchell-Plateaus wirken den gegensätzlichen Auswirkungen von Landhebung (epirogenetischer Bewegung) und darauf folgender Abflachung (durch Erosion) damit verbundene schwache synklinale Verzerrungen entgegen, so daß die Bauxit-Lager Übergangszonen zweier Küstengebiete von mindestens zwei aufeinanderfolgenden Erosions(gelände)zyklen bildeten. Nach der Kreide- und Tertiär-Periode der Bauxitisation durch Eigenauslaugung lagen diese Gebiete teilweise unter dem Meeresspiegel und wurden vor allem am Mitchell Plateau weitgehend aufgearbeitet. Mit Hilfe von quantitativen Analysen von Schwermineralen können deutliche Diskordanzen zwischen mehreren Bauxitprofilen festgestellt werden. Abschließend wird die quantitative Mineralogie beider Lager detailliert diskutiert und deren Ursprung (gestützt auf experimentelle Untersuchungen) vorgeschlagen.
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15.
The Carneal plug, Co. Antrim, Northern Ireland, is a Tertiarydolerite intrusion, 150 m in diameter, which incorporates blocks(up to several metres across) of the underlying Cretaceous Chalkand the flints originally contained in the Chalk. It is oneof the rare natural occurrences showing reaction between basalticmagma and limestone under conditions of very high temperatureand low pressure. The pressure was controlled by lithostaticload at about 0.2 kb; the upper temperature limit for the progradereactions was close to the liquidus temperature of basalticmagma around 1100 °C and retrograde reactions with secondaryhydrous fluids have produced a series of hydrated calc-silicatesover the temperature range 700 °C to less than 100 °C.The rocks form complex assemblages with two complementary suitesof rocks developed by the metamorphic and metasomatic reactions.An exomorphic suite, derived mainly from the chalk, consistsof assemblages of larnite, spurrite, bredigite, merwinite, melilite(gehlenite), calcite, or spinel; and wollastonite, melilite,hibschite and quartz derived from flint. The endomorphic suiteis derived by desilication reactions between the basic magmaand the incorporated chalk and flint. The minerals are thoseof the dolerite, together with fayalitic olivine, sahlite, nepheline,aegirine, wollastonite, melilite (humboldtilite), merwinite,scawtite, and hydrogrossular. Retrograde processes provide afurther range of scarce to rare mineral suites. The Carnealplug thus provides an ideal opportunity to investigate the applicationof strontium isotope-ratio measurements to crustal contaminationof basic magmas, since the three rock end-members dolerite,chalk, and flint, are readily identifiable and relatively homogeneous,and the conditions of the formation of the resulting metamorphicand metasomatic rocks are well understood. Although the petrology, albeit complicated, is well established,few geochemical and no isotopic studies have hitherto been made.Major- and trace-element data for a total of twenty-one whole-rocksamples (thirteen new analyses from the plug) are now reported.Strontium isotope ratios for these samples (with two mineralseparates), forty-two samples of Cretaceous Chalk and five samplesof unmetamorphosed flints from other localities or regions arealso presented and discussed. Strontium isotope ratios are alsogiven for pore-water from the Chalk, and drill-stem test watersamples from Irish Triassic strata. The main conclusions which may be drawn are as follows: The petrological identity of the two complementary suites ofmineral assemblages is reflected by the new geochemical data.Initial 87Sr/86Sr ratios presented for the end-members, chalk,flint, and dolerite show that the initial ratios in the metamorphicassemblages cannot be produced by simple mixtures of these end-members. A major component of the strontium budget in the metamorphicassemblages in the Carneal plug appears to have been transportedinto the plug probably in a secondary, low-temperature fluidphase containing Sr with higher 87Sr/86Sr ratios. Strontiumand thus probably calcium were mobile on a relatively largescale during the prograde metamorphism as well as during theretrograde stages. Metasomatism was an important process during metamorphism andmany elements were mobile on the relatively small scale of thehand specimens. The new studies show for example that the exomorphicassemblages have contents of Mg, Ni, and Cu which were mostprobably derived from the enclosing dolerite magma. The contentsof major elements in many of the assemblages differ from concentrationsto be expected as a result of simple mixtures of the three end-membersbut may be explained in terms of phase equilibria during contamination. The new high precision 87Sr/86Sr ratios determined for Chalksamples of known stratigraphic position suggest that there maybe sufficient variation between stratigraphical Stages to usesuch measurements as a method of correlating or dating Mesozoicand Cenozoic limestones.  相似文献   

16.
Study of the cross-stratification and other sedimentary structures in the Lower Greensand of the Weald, England, and Bas-Boulonnais, France, indicates that the sediments were deposited by the lateral migration of sand waves in a neritic sea. Comparison of the Lower Greensand sea with the modern North Sea was attempted. If those sediments were deposited as a result of tidal current similar to the present-day North Sea then the Lower Greensand shoreline could be deduced as running northwest-southeast, indication that the western part of the London Platform was submerged.  相似文献   

17.
The dielectric constants and dielectric loss values of 4 Ca-containing minerals were determined at 1 MHz using a two-terminal method and empirically determined edge corrections. The results are: vesuvianitel κ′ a=9.93 tan δ=0.006 κ′ c=9.79 tan δ=0.005 vesuvianitel κ′ a=10.02 tan δ=0.002 κ′ c=9.85 tan δ=0.003 zoisite1 κ′ a =10.49 tan δ=0.0006 κ′ b =15.31 tan δ=0.0008 κ′ c=9.51 tan δ=0.0008 zoisite2 κ′ a =10.55 tan δ=0.0011 κ′ b =15.45 tan δ=0.0013 κ′ c=9.39 tan δ=0.0008 epidote κ′ 11= 9.52 tan δ=0.0008 κ′ 22=17.1 tan δ=0.0009 κ′ 33= 9.37 tan δ=0.0006 fluorapatite1 κ′ a =10.48 tan δ=0.0008 κ′ c = 8.72 tan δ=0.0114 fluorapatite2 κ′ a =10.40 tan δ=0.0010 κ′ c=8.26 tan δ=0.0178 The deviation (δ) between measured dielectric polarizabilities as determined from the Clausius-Mosotti equation and those calculated from the sum of oxide polarizabilities according to α D (mineral)=∑ α D (oxides) for vesuvianite is ～ 0.5%. The large deviations of epidote and zoisite from the additivity rule with Δ=+ 10.1 and + 11.7%, respectively, are attributed to “rattling” Ca ions. The combined effects of both a large F thermal parameter and possible F-ion conductivity in fluorapatite are believed to be responsible for Δ=+2–3%. Although variation of oxygen polarizability with oxygen molar volume (Vo) is believed to affect the total polarizabilities, the variation of Vo in these Ca minerals is too small to observe the effect.  相似文献   

18.
Sand bars of the three important rivers of the Gangetic Alluvium, namely the Ganga, Yamuna and Son are investigated. Megaripples of undulatory type are the most abundant bed forms present, and are responsible for the development of large-scale cross-bedding, the most common bedding structure present in the area. Giant ripples, with superimposed megaripples are recorded in one sand bar in the Yamuna River. On a steeply sloping point bar in the Ganga River, delta-like lobes have produced foreset bedding oriented towards the main channel, at right angles to the direction of the main flow.  相似文献   

19.
Over the past decade researchers working on the rocks of the Beaufort Group in the main Karoo Basin of South Africa have vastly increased our understanding of this important Permo-Triassic sequence. Many new fossil forms have been discovered, allowing for breakthroughs into the biodiversity, biogeography and biostratigraphy of the group. Taxonomic and phylogenetic advances are many and varied, and cover most of the vertebrate taxa, but with emphasis placed on the temnospondyl amphibians, archosauriforms and non-mammalian synapsids, in particular the anomodontia. Biostratigraphic breakthroughs have centered on the Middle Permian Eodicynodon and Tapinocephalus assemblage zones, the Late Permian Dicynodon Assemblage Zone, and the Triassic Lystrosaurus and Cynognathus assemblage zones. Correlation of these biozones with better dated sequences in Europe, Russia and China has allowed for many chronostratigraphic refinements, which are in turn vital for sequence stratigraphical analysis of the basin fill. Based on fossil data, both the lower (Ecca–Beaufort) and upper (Beaufort–Molteno) contacts of the group have been proved to be highly diachronous. The refined chronostratigraphic framework has also allowed for a better analysis of the basin evolution through time, particularly in terms of the correlation of external stimuli that affect basin sedimentation patterns.  相似文献   

20.
Helium,neon, and argon in the iron meteorites Dongling,Nantan and Ningbo   总被引：1，自引：0，他引：1  
The light noble gases He, Ne and Ar have been measured in the iron meteorites Dongling, Nantan and Ningbo. Dongling and Ningbo show a deficit of cosmic-ray that produced3He of ca. 30% and 10%, respectively, which is argued to be caused by the loss of3H (tritium) from the meteoroids during the time of their exposure to the cosmic radiation. Nantan has the lowest content of noble gases as yet reported for any iron meteorite. Cosmogenic3He and38Ar are only about 1/5000 of those in Dongling which has particularly interesting implications if the two meteorites belong to the same fall[2]. In addition, Nantan contains nonspallogenic4He which we believe to be of radiogenic origin. This radiogenic4He, together with a U-content of 2.6×10−11 g/g[20] yields a4He retention age close to the cosmic-ray exposure age of Dongling. If Dongling and Nantan were part of the same meteoroid[2], this result would indicate that He retention in the meteoroid age were 4,500 Ma, a U-content of less than 7.2×10−13 g/g is required to explain the non-cosmogenic4He present. An upper limit to the number of transuranium or superheavy-element atoms which have decayed by α-emission in Nantan since onset of He retention is 2×1010 per gram.  相似文献   

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