South African geography and post-apartheid reconstruction

South African geography and post-apartheid reconstruction     

南印度洋海区营养盐的分布特征

探讨了南印度洋海区总有机磷(TOP)、总有机氮(TON)以及溶解无机营养盐的分布规律。分析结果表明：研究海区内溶解无机营养盐受水体中生物活动和物理过程的综合影响,表层水体由于生物活动的消耗,其磷酸盐等无机营养元素的含量一般是采样水深范围内最低的;中深层水体由于生物活动的降低以及有机质矿化作用的影响,无机营养元素的变化范围较小。表层水体中TOP和TON含量占TP和TN的主要部分,说明表层水体中的氮和磷主要以有机态形式存在,且沿着37.8°S从西向东,TOP和TON的含量以及TOP/TP和TON/TN的比值呈降低的趋势。研究海区叶绿素a的分析结果表明,初级生产力的变化可能是控制研究海区TON和TOP空间分布的主要因素。不同形态氮、磷营养元素的相关分析表明,有机营养盐和无机营养盐之间互为补充,且表层水体中有机氮和磷是水体初级生产所需营养盐的重要来源,总氮、总磷的关系表明研究区初级生产力并不受氮、磷的限制。     

Japan's hidden involvement in South African manufacturing

This paper examines the development of Japanese involvement in South African manufacturing. In the extensive literature dealing with the growth and spread of Japanese investment abroad the unique situation of Japanese companies in South Africa has been overlooked. Despite the introduction of a ban on direct investment in South Africa there is a considerable hidden Japanese presence in local manufacturing which resulted from licensing arrangements. In particular, Japanese enterprise is strongly represented in the South African motor-vehicles sector where it is at the forefront in innovating new flexible production systems.     

Diagenetically formed ooids and intraclasts in South African calcretes

Certain South African calcrete (caliche) beds contain structures that very closely resemble normal marine ooids and intraclasts. The ooids/intraclasts are actually non-marine in origin, and were formed by an in situ process of calcretization and selective neomorphism. The term ‘diagenetic ooids/intraclasts’ is thus applied to distinguish these grains from marine ooids/intraclasts. Quaternary calcretes contain the only known ooids/intraclasts in any South African Cretaceous or Cainozoic rocks. The diagenetic grains are believed to have formed in the following manner. Rain water percolates through an unlithified calcareous sand deposit, dissolving carbonate along its downward path. This carbonate-laden water is eventually checked in its descent and drawn upward somewhat by capillary action. Evaporation and soil suction in the uppermost zones of the sediment body cause precipitation of a concentric coating of carbonate mud around individual grains (incipient ooids) or composites of grains (incipient intraclasts). As this dissolution-precipitation cycle is repeated the micritic coatings thicken and locally push grains apart. At this stage three things can happen: (a) sparry calcite may be introduced as an intergranular cement (very rare in these calcretes), (b) wet carbonate mud may fill the pore spaces and lithify to micrite (common), or (c) wet carbonate mud may fill the pore spaces and neomorphose to microspar (common). The last process causes ooids/intraclasts to stand out distinctively, since they are opaque, micrite-coated grains set in a fabric of clear microspar. This selective neomorphism of the micritic mud in pore spaces, rather than the micritic mud forming ooids/intraclasts, is probably a function of rapidity of lithification. The micrite of the coatings must have lithified quickly, before neomorphic crystal enlargement could occur, whereas lithification of the intergranular mud was delayed long enough for the growth of microspar crystals.     

Sulphate generation in South African underground and opencast collieries

Deterioration in the water quality results from coal mining, and the significant impact on the environment in South Africa has been reported (Funke in SA Water, Sci Technol 15:115–144; 1983). Pyrite in with South African coal can be oxidised to yield acidic and high salinity water. This study deals with the rate at which sulphate could be produced for collieries under different conditions. Four collieries in the Witbank coalfield were selected for this investigation. The boreholes were investigated with an in-situ multi-parameter probe, and then sampled at different times with a specific depth sampler to determine the chemical composition of the water in the collieries. Water level measurements and volumetric calculations were done to determine influx rates. Daily sulphate generation rate for underground mining was found to be in the range of 0.4–2.7 kg/ha, depending on the availability of oxygen and the residence time of the water (the time available for neutralising agents present to react) in the mining void. The exclusion of oxygen due to flooding and the presence of calcareous carbonates influences the observed sulphate generation.     

African, southern Indian and South American cratons were not part of the Rodinia supercontinent: evidence from field relationships and geochronology

We discuss the question whether the late Mesoproterozoic and early Neoproterozoic rocks of eastern, central and southern Africa, Madagascar, southern India, Sri Lanka and South America have played any role in the formation and dispersal of the supercontinent Rodinia, believed to have existed between about 1000 and 750 Ma ago. First, there is little evidence for the production of significant volumes of ˜1.4–1.0 Ga (Kibaran or Grenvillian age) continental crust in the Mozambique belt (MB) of East Africa, except, perhaps, in parts of northern Mozambique. This is also valid for most terranes related to West Gondwana, which are made up of basement rocks older than Mesoproterozoic, reworked in the Brasiliano/Pan-African orogenic cycle. This crust cannot be conclusively related to either magmatic accretion processes on the active margin of Rodinia or continental collision leading to amalgamation of the supercontinent. So far, no 1.4–1.0 Ga rocks have been identified in Madagascar. Secondly, there is no conclusive evidence for a ˜1.0 Ga high-grade metamorphic event in the MB, although such metamorphism has been recorded in the presumed continuation of the MB in East Antarctica. In South America, even the Sunsas mobile belt, which is correlated with the Grenville belt of North America, does not include high-grade metamorphic rocks. All terranes with Mesoproterozoic ages seem to have evolved within extensional, aulacogen-type structures, and their compressional deformation, where observed, is normally much younger and is related to amalgamation of Gondwana. This is also valid for the Trans-Saharan and West Congo belts of West Africa.Third, there is also no evidence for post-1000 Ma sedimentary sequences that were deposited on the passive margin(s) of Rodinia. In contrast, the MB of East Africa and Madagascar is characterized by extensive structural reworking and metamorphic overprinting of Archaean rocks, particularly in Tanzania and Madagascar, and these rocks either constitute marginal parts of cratonic domains or represent crustal blocks (terranes or microcontinents?) of unknown derivation. This is also the case for most terranes included in the Borborema/Trans-Saharan belt of northeastern Brazil and west-central Africa, as well as those of the Central Goíás Massif in central Brazil and the Mantiqueira province of eastern and southeastern Brazil.Furthermore, there is evidence for extensive granitoid magmatism in the period ˜840 to <600 Ma whose predominant calc-alkaline chemistry suggests subduction-related active margin processes during the assembly of the supercontinent Gondwana. The location of the main Neoproterozoic magmatic arcs suggests that a large oceanic domain separated the core of Rodinia, namely Laurentia plus Amazonia, Baltica and West Africa, from several continental masses and fragments now in the southern hemisphere, such as the São Francisco/Congo, Kalahari and Rio de La Plata cratons, as well as the Borborema/Trans-Saharan, Central Goiás Massif and Paraná blocks. Moreover, many extensional tectonic events detected in the southern hemisphere continental masses, but also many radiometric ages of granitois that are already associated with the process of amalgamation of Gondwana, are comprised within the 800–1000 age interval. This seems incompatible with current views on the time of disintegration of Rodinia, assumed to have occurred at around 750 Ma.     

Researching the South African tourism and development nexus

Under apartheid, tourism was essentially anti-developmental in focus and tourism research largely centred on the recreation of white South Africans. Since the 1994 democratic transition tourism has become recognised as an increasingly important sector for South Africa's economy and for achieving the government's goals for reconstruction and development. In this paper a review and critical analysis is presented of the changing directions and foci of tourism scholarship in South Africa. It is shown that South African scholars are beginning to respond to the challenges posed by tourism as a developmental focus. This revised version was published online in August 2006 with corrections to the Cover Date.     

Trace element distribution and risk assessment in South Indian surface waterways

The concentrations of 27 major and trace elements are determined in surface water samples collected from 48 sites of diverse waterways in four states (Tamil Nadu, Kerala, Karnataka, and Telangana) of South India. The aims of this study are to identify the element distribution, comparatively assess the pollution risk, and evaluate human health risks related to diverse waterways in the study area. The results indicate that elements such as Cr, Se, As, Fe, and Mn are the major pollutants, as their concentrations exceeded the acceptable national and international water quality standards in several sites of Ennore, Adyar, Cooum, Periyar, and Vrishabhavathi rivers. Furthermore, statistical analysis reveals that the Ennore, Adyar, Cooum, Periyar, and Kaveri river basins are affected by various anthropogenic activities, leading to moderate-to-high pollution by As, Cr, Mn, Fe, and Se. Potential pollution sources are industrial waste, sewage intrusion, paint industry waste, and automobile runoff. Overall, the investigated sites are categorized into three major groups: highly, moderately, and least polluted. Risk on human health by metals is then evaluated using hazard quotients (HQs) and carcinogenic risk evaluation; the results indicated that As with HQ >1 is the most hazardous pollutant, which could lead to non-carcinogenic and carcinogenic concerns, particularly in children. This study helps in establishing pollutant loading reduction goal and the total maximum daily loads and consequently contributes to preserving public health and developing water conservation strategies.     

The African Renaissance and its relation to the geosciences: a South African perspective

Implicit in the African Renaissance is the synergy between government, the private sector, the educated minority and the disadvantaged majority. For this concept to work, belief and commitment must arise first from the African individual, whatever his or her potential contribution may be. The geosciences in South Africa provide a currently vibrant example of such cooperation, which has the potential to contribute significantly to the upliftment of the country and its neighbouring states. Based largely on personal interviews with various role players, from the Presidency of South Africa, through ministerial levels, the corporate sector and down to the individual, we present a spectrum of viewpoints and initiatives which are starting to result in practical implementation of the African revival. An end to conflict and xenophobia, the entrenchment of democratic government and corporate expression of the entrepreneurial spirit are essential to provide the framework within which the individual African can become a “Renaissance Man or Woman”.     

Authigenic pyrite and gypsum in South West African continental slope sediments

An unusual association of authigenic pyrite and authigenic gypsum has been found in silty clays recovered from the South West African continental slope. Nannofossil content suggests that the sediments are Upper Miocene-Lower Pliocene in age. Pyrite occurs as (1) granular masses, (2) ‘worm’tubes, (3) foraminiferal infillings, and (4) framboids. Gypsum occurs as euhedral single or twinned crystals of selenite. ‘Worm’tubes and foraminiferal infillings of pyrite are partially or completely enclosed in some gypsum crystals. Electron microprobe analyses show a relatively high concentration of manganese in both the granular masses and tubes. Present-day waters off this coast are dominated by the upwelling of cold, nutrient-enriched waters (the Benguela Current). These rich waters support an enormous population of plankton. Death and decomposition of these plankton consume oxygen, thereby creating a belt of anaerobic sediments close to shore. An Upper Miocene-Lower Pliocene regression (Dingle & Scrutton, 1974) lowered sea level and shifted an older analogue of this upwelling zone seaward, eventually establishing an anaerobic environment in places on the present continental slope. Anaerobic bacteria thrived in these conditions. They reduced SO₄ dissolved in sea water, initiating the formation of H₂S. The H₂S reacted with iron minerals present in the sediment to form FeS. Addition of elemental sulphur produced pyrite. This strongly reducing, low pH, environment became saturated with calcium obtained by the dissolution of planktonic calcareous organisms. Gypsum was precipitated once the product of the concentrations of dissolved calcium and SO₄ exceeded the gypsum solubility product.     

Phlogopites and potassic richterites from mica nodules in South African kimberlites

Mica nodules from the Dutoitspan and Wesselton mines, Kimberley can be divided into two groups: diopside-phlogopite nodules and potassic richterite-phlogopite nodules. The latter is characterized by the presence of abundant potassic richterite (less than 50% by volume) and large size of the crystals (up to 1 cm in length). It seems this type nodule is the first finding. Phlogopites and potassic richterites show a rather wide variations of major elements they have low Al₂O₃ and high Fe₂O₃, with Fe⁺³ in addition to Al⁺³ in the tetrahedral sites. It is believed that the mica nodules would be produced from kimberlitic and related magmas under moderate temperature and pressure conditions.     

Garnet peridotite xenoliths in South African kimberlite pipes and their petrogenesis

Whole rock analyses are presented for nine garnet peridotite, two garnet pyroxenite, one garnet free peridotite and two highly altered garnet peridotite xenoliths from South African kimberlite pipes. Garnets from eight of these samples have also been chemically analysed, while olivine compositions in the twelve fresh samples have been estimated by X-ray diffraction. The chemistry and mineralogy of these specimens are compared with the results of previous studies, and the controversies concerning the petrogenesis of these xenoliths are discussed in detail.     

A comparison of Indian and African monsoon variability at different time scales

A review is given of the summer monsoon systems in Africa and India, and of their comparison at different time scales. Features of the circulation are described first, including the main respective meteorological centres of action controlling the annual cycle of the rain bands over these two regions. The main elements of the atmospheric intraseasonal variability are then presented, which controls in particular the onset of these two monsoon systems. Then the sensitivity of these two monsoon systems to oceanic and continental surface conditions in the context of interannual variability is discussed and compared. Consequences in term of predictability are commented. Finally, the Intergovernmental Panel on Climate Change (IPCC4) scenarios of the future climate over these two regions are presented.     

The isotopic composition of strontium in some South African kimberlites

Strontium isotopic studies of kimberlites reveal no significant differences between the respective whole-rock Sr⁸⁷/Sr⁸⁶ ratios of fissure and pipe kimberlites. Kimberlites from the Swartruggens fissure (calcareous micaceous kimberlite) have Sr⁸⁷/Sr⁸⁶ ratios of from 0.709 to 0.716, whilst those from the Wesselton pipe have Sr⁸⁷/Sr⁸⁶ ratios of from 0.708 to 0.715. Other kimberlites range from 0.706 to 0.715. Samples are considered to be late Cretaceous to early Tertiary and thus the ratios are approximately initial ratios. The Sr⁸⁷/Sr⁸⁶ ratios bear no relation to the Rb or Sr content of individual kimberlite bodies. The high initial ratios are not due to bulk assimilation of granitic material in either a kimberlite or carbonatitic magma. Rb-Sr data for garnet peridotites and eclogite xenoliths in kimberlite are not compatible with production of kimberlite by eclogite fractionation from a melt derived from garnet lherzolite. The Sr isotopic composition of kimberlite is compatible with partial melting of garnet mica peridotite. The isotopic composition of liquids formed by partial melting of this rock can be modified by (i) gross contamination with material of low Sr⁸⁷/Sr⁸⁶ ratio or (ii) selective diffusion of material of high Sr⁸⁷/Sr⁸⁶ ratio into kimberlitic fluids.     

The spatial formation of the South African City

The south African social formation is characterised by a distinctively large social distance. This paper traces the evolution of the social formation, identifies some of its parameter and demonstrates its on the urbanisation process and the urban structure. Within this framework, a Segregation City and an Apartheid City are recognised, representing two sequential but interrelated phases of urban development separated by the acceptance of a formal Apartheid ideology and development strategy from 1948 onwards.     

Limestone lithofacies from the South African continental margin

Carbonate sedimentation has played an important part in the Cainozoic history of the South African offshore areas. The Agulhas Bank sector of the continental shelf and upper slope is covered by a patchy veneer of relict and Recent sediment. Under this thin cover of sediment lies a succession of Cainozoic carbonate rocks very different from those exposed onshore. The Agulhas Bank rocks have been divided into the following lithofacies: (1) lagoonal-quartzose lime wackestones; (2) pelagicforaminiferal lime packstones; and (3) infralittoral-skeletal lime packstones. The rocks within each lithofacies are not necessarily time-equivalents; indeed any one lithofacies may have a considerable time range.     

Dimensions of drought: South African case studies

The recent drought in southern Africa has underscored the need for detailed analysis of the phenomenon. While geographers have researched the causes and impacts of drought in many African contexts, South Africa and in particular its Bantustans have not received sufficient similar attention. This paper outlines firstly the dimensions of drought in South Africa, including the biophysical and socio-economic factors. Issues such as land-use management, drought planning and relief are interrogated in the South African context. The final section of the paper highlights these debates with specific reference to case studies of past and present drought initiatives in South Africa.