The impact of residential desegregation on social integration: Evidence from a South African neighbourhood

This paper analyses the potential for social integration in post-apartheid urban South Africa by examining the lives of those already living in desegregated spaces. The case study is a low-cost state-assisted housing project situated in the wealthy southern suburbs of Cape Town. In this social housing project, named Westlake village, coloured and Black African (alongside a handful of white and Indian) residents were awarded state housing in 1999 as replacement for their previous homes (informal and formal), which were demolished to make way for a mixed land-use development, of which their new homes form a small component. Westlake’s desegregation is found to extend beyond mere residential abode, affecting resident’s everyday lives to the extent that apartheid’s history and geography are superseded by other factors (such as proximity and affordability) in decision-making. Furthermore, integration at the everyday level of informal neighbourly mixing is prevalent. Although more formal cross-race friendships are rare, discussion reveals this as a consequence of Westlake’s specific socio-historic identity rather than racial divisions per se. Empirical evidence is used to propose a continuum of social integration experience. This continuum addresses the form of integration, for example greeting in the street, visiting homes, inter-marriage; and also the spaces of integration, for example physical space (shared neighbourhood), economic space (common employment-type), social space (cross-race friendship), political space (common involvement in civic organisations) and cultural space (shared sense of belonging).     

Geochemistry of soils derived from black shale, central Hunan, China

The black shale formed under anoxic conditions usually contains high concentrations of many metals. Weathering of such black shale might cause the emission of many metals. Moreover, soils derived from black shale （SBS） are believed to be affected by black shale weathering. In recent years, many studies such as Lee et al. （2002）, Woo et al. （2002）, Fang et al. （2002）, Pasava et al. （2003）, and Peng et al. （2004） have approached the heavy metal contaminations of SBS, but systematical geochemical study is rare. Presently, the SBS and its corresponding black shales （CBS） were both sampled from central Hunan （China）, and analyzed for a large number of elements, using an Elan6000 ICP-MS/AES machine at Guangzhou Institute of Geochemistry, CAS. In this paper, some preliminary results are reported. The analytical results show that the SBS in central Hunan contains very high concentrations of heavy metals such as Co, Cu, Hg, Mo, Pb, Zn, U, Th, Sb, T1, Cd, Cr, Sc, V, Sn, As, Se, and Ni.     

中国城市群发育现状分析

伴随着市场经济和工业化、城市化的推进。中国城市群正在逐渐形成并快速发展。文章在对城市群概念进行讨论的基础上，选取2002年各项经济指标，从总体经济实力、人均发展水平、中心城市与县域经济发展状况诸方面，对中国各大城市群的发育状况与存在问题进行了综合对比分析，强调国家应采取以城市群为依托的“多极联动”区域发展战略。     

Poverty, vulnerability and the impact of flooding in the Limpopo Province, South Africa

The article evaluates household vulnerability after the 2000 flood in two poor communities of the Limpopo Province, South Africa. The study analyses the forms of vulnerability which disasters such as floods present. Using data gathered from a survey of households, the study presents the impacts, coping and adapting strategies of households after the 2000 flood. The article argues that beyond the concern over socio-economic circumstances as the major determinant of household vulnerability, the management of the disaster can serve to perpetuate vulnerability.     

The changing role of hydrogeology in semi-arid southern and eastern Africa

Much of southern and eastern Africa is semi-arid and heavily groundwater dependent. Borehole drilling commenced over a hundred years ago with magnetic and electrical resistivity surveys for borehole siting being introduced from 1936. Formalised training of hydrogeologists led in the 1970s to an almost standard approach to hydrogeological investigation and a period of stability followed, during which some major investigations were carried out. A period of decentralisation and fragmentation has since taken place in many parts of southern and eastern Africa, and groundwater monitoring and management are inadequate in many countries. All but six of the 14 SADC (Southern African Development Community) member states reportedly have an adequate monitoring network in place. However, groundwater demand is increasing and hydrogeologists need to promote the use of appropriate methodologies as an essential part of tackling the severe issues now facing the water sector in the region.     

Planation, bauxites and epeirogeny: One or two paleosurfaces on the West African margin?

Mapping of lateritic bauxites over the West African rifted margin and analysis of the geomorphic properties of these bauxites, combined with available geological data lead to a discussion of the presence of either two Meso-Cenozoic planation surfaces or a single Eocene surface to account for the morphotectonic and paleoclimatic evolution of the Guinean landforms. At large scale, two stepped bauxitic levels are documented. Ongoing or episodic uplift following Gondwana breakup and Meso-Cenozoic climate change are proposed to have allowed the formation and abandonment of an Early mid-Cretaceous surface today preserved as the higher bauxitic level, and the setting of an Eocene planation surface bearing a second generation of bauxites, making the lower bauxitic level. The single Eocene surface hypothesis requires that Paleogene bauxitization preserved large pre-existing relief to explain two stepped bauxitic levels of the same age. The two-surface hypothesis is favored because it would explain rebauxitization of alluvial pebbles of bauxites under the lower lateritic level.     

Early Holocene water budget of the Nakuru-Elmenteita basin, Central Kenya Rift

The Nakuru-Elmenteita basin in the Central Kenya Rift, contains two shallow, alkaline lakes, Lake Nakuru (1770 m above sea level) and Lake Elmenteita (1786 m). Ancient shorelines and lake sediments at 1940 m suggest that these two lakes formed a single large and deep lake as a result of a wetter climate during the early Holocene. Here, we used a hydrological model to compare the precipitation–evaporation balance during the early Holocene to today. Assuming that the Nakuru-Elmenteita basin was hydrologically closed, as it is today, the most likely climate scenario includes a 45% increase in mean-annual precipitation, a 0.5°C decrease in air temperature, and an increase of 9% in cloud coverage from the modern values. Compared to the modeling results from other East African lake basins, this dramatic increase in precipitation seems to be unrealistic. Therefore, we propose a significant flow of water from the early Holocene Lake Naivasha in the south towards the Nakuru-Elmenteita basin to compensate the extremely negative hydrological budget of this basin. Since we did not find any field evidence for a surface connection, as often proposed during the last 70 years, the hydrological deficit of the Nakuru-Elmenteita basin could have also been compensated by a subsurface water exchange.     

The Paleoproterozoic carbonate-hosted Pering Zn–Pb deposit, South Africa: I. Styles of brecciation and mineralization

The Pering deposit on the Ghaap Plateau, Northwestern Province, South Africa, was the largest of several Zn–Pb occurrences hosted by Neoarchean platform dolostones of the Transvaal Supergroup. With a Paleoproterozoic mineralization age, these occurrences are widely regarded as the oldest representatives of Mississippi Valley-type Pb–Zn deposits. Hosting an initial resource of 18 Mt at an average grade of 3.6 wt% Zn and 0.6 wt% Pb, the Pering deposit was mined from 1984 until its final closure at the end of November 2002. In this study, available geological and grade distribution maps were evaluated and complemented by the examination of mining-related outcrops, drill core, and a large set of ore and host rock samples. Four different styles of brecciation can be distinguished at the Pering deposit: (1) pyritic rock matrix breccia; (2) chemical wear breccia; (3) mosaic breccia; and (4) crackle breccia. Geological and mineral paragenetic observations on these different breccia types suggest that the formation of the Pering deposit commenced with an initial stage of hydrothermal karstification. Large volumes of pyritic rock matrix breccia formed by wall rock collapsing into the open space attributed to carbonate dissolution. This stage of hydrothermal karstification acted as ground preparation for the subsequent mineralization event. By the upward advance of the hydrothermal karstification process, fluid reservoirs in the previously undisturbed dolostone host rock succession were tapped, ultimately leading to fluid mixing. Hydrothermal sulphides are the most abundant where fluid mixing was most effective, i.e. along the outer and upper margins of the breccia bodies, and in stratabound zones along permeable host rock units. Chemical wear brecciation and formation of large volumes of fine-grained replacive sphalerite mineralization mark the early stage of hydrothermal Zn–Pb mineralization associated with this fluid mixing. The fine-grained stage of sulphide mineralization was succeeded by very coarse-grained open-space-infill mineralization. The latter is very uniform across the entire deposit and typically cements mosaic and crackle breccia, but also fills remaining open space within chemical wear brecciated portions of the deposit.     

Petrology, geochemistry and the mechanisms determining the distribution of platinum-group element and base metal sulphide mineralisation in the Platreef at Overysel, northern Bushveld Complex, South Africa

Platinum-group element (PGE) mineralisation within the Platreef at Overysel is controlled by the presence of base metal sulphides (BMS). The floor rocks at Overysel are Archean basement gneisses, and unlike other localities along the strike of the Platreef where the floor is comprised of Transvaal Supergroup sediments, the intimate PGE–BMS relationship holds strong into the footwall rocks. Decoupling of PGE from BMS is rare and the BMS and platinum-group mineral assemblages in the Platreef and the footwall are almost identical. There is minimal overprinting by hydrothermal fluids; therefore, the mineralisation style present at Overysel may represent the most ‘primary’ style of Platreef mineralisation preserved anywhere along the strike. Chondrite-normalised PGE profiles reveal a progressive fractionation of the PGE with depth into the footwall, with Ir, Ru and Rh dramatically depleted with depth compared to Pt, Pd and Au. This feature is not observed at Sandsloot and Zwartfontein, to the south of Overysel, where the footwall rocks are carbonates. There is evidence from rare earth element abundances and the amount of interstitial quartz towards the base of the Platreef pyroxenites that contamination by a felsic melt derived from partial melting of the gneissic footwall has taken place. Textural evidence in the gneisses suggests that a sulphide liquid percolated down into the footwall through a permeable, inter-granular network that was produced by partial melting around grain boundaries in the gneisses that was induced by the intrusion of the Platreef magma. PGE were originally concentrated within a sulphide liquid in the Platreef magma, and the crystallisation of monosulphide solid solution from the sulphide liquid removed the majority of the IPGE and Rh from it whilst still within the mafic Platreef. Transport of PGE into the gneisses, via downward migration of the residual sulphide liquid, fractionated out the remaining IPGE and Rh in the upper parts of the gneisses leaving a ‘slick’ of disseminated sulphides in the gneiss, with the residual liquid becoming progressively more depleted in these elements relative to Pt, Pd and Au. Highly sulphide-rich zones with massive sulphides formed where ponding of the sulphide liquid occurred due to permeability contrasts in the footwall. This study highlights the fact that there is a fundamental floor rock control on the mechanism of distribution of PGE from the Platreef into the footwall rocks. Where the floor rocks are sediments, fluid activity related to metamorphism, assimilation and later serpentinisation has decoupled PGE from BMS in places, and transport of PGE into the footwall is via hydrothermal fluids. In contrast, where the floor is comprised of anhydrous gneiss, such as at Overysel, there is limited fluid activity and PGE behaviour is controlled by the behaviour of sulphide liquids, producing an intimate PGE–BMS association. Xenoliths and irregular bands of chromitite within the Platreef are described in detail for the first time. These are rich in the IPGE and Rh, and evidence from laurite inclusions indicates they must have crystallised from a PGE-saturated magma. The disturbed and xenolithic nature of the chromitites would suggest they are rip-up clasts, either disturbed by later pulses of Platreef magma in a multi-phase emplacement or transported into the Platreef from a pre-existing source in a deeper staging chamber or conduit.     

豫陕交界地区钾长石矿产地质特征及开发前景

本文研究证明区内有南、北两条钾长石成矿带，其产出形态、矿化特征、矿石类型均有差异，且导致了它们在工业应用上的不同。区内矿体以岩脉或岩株产出，有红色、浅红色、白色3种矿石。白色矿石富钾低铁，达到国标一级品，其余矿石为二级以下品级，均具有一定的销售市场。从全国的供需形势分析，今后钾长石矿产品市场前景广阔，而区内钾长石资源进一步找矿的潜力仍然很大。