uTshani BuyaKhuluma––The Grass Speaks: the political space and capacity of the South African Homeless People’s Federation

The point of departure for this article is the contemporary tendency towards localisation of politics in the context of neo-liberal globalisation. Mediated through institutional reforms, political discourses and localised struggles, this localisation of politics produce new and transformed local political spaces. The purpose of the article is to examine the capacity of popular movements to use and transform such political spaces within the South African housing sector. This analysis is done through a combination of conceptual examination of political space and actor capacity and a concrete case study of the political strategies and capacities of The South African Homeless People’s Federation. The article argues that the Federation has utilised political relations at different scales to mobilise resources such as land and subsidies for housing for its members. It has also influenced the formulation of housing policies through its discourses and practical experiences with people-driven housing processes. In consequence the Federation’s ability to function as a civil/political movement has granted them a certain capacity to participate in the complicated process of turning de jure rights to adequate shelter into de facto rights for the urban poor as citizens of a democratic South Africa.     

Chemical and isotopic variations along the superfast spreading East Pacific Rise from 6 to 30°S

Chemical data of 39 fresh basaltic glasses from the East Pacific Rise (EPR) between 6 and 30°S and Pb, Sr, and Nd isotopic compositions of 12 basalt glasses are presented. Major and trace element data indicate a wide compositional range, including primitive basalts (Mg#=0.67) and highly evolved FeTi-basalts (Mg#=0.34) [molMg/(Mg+Fe²⁺)]. The compositional range can be attributed to low-pressure fractional crystallization. Fractionation-corrected major element concentrations provide evidence for varying mantle melting conditions. Calculations of the melting conditions suggest melt generation in a rising upper mantle column between 20 and 10 kbar, at temperatures between 1430 and 1280°C, and total degrees of partial melting between 17 and 20% by weight. Leached and hand-picked basalt glasses display large variations in ⁸⁷Sr/⁸⁶Sr (0.70235–0.70270), ¹⁴³Nd/¹⁴⁴Nd (0.51312–0.51323), and ²⁰⁶Pb/²⁰⁴Pb (18.064–18.665), but are similar to other N-type MORB from the EPR. The isotopic ratios of basalts from 13 to 23°S show strong correlations and delineate two systematic trends. From 23 to 17°S, ⁸⁷Sr/⁸⁶Sr and Pb isotope ratios increase and ¹⁴³Nd/¹⁴⁴Nd decrease in agreement with previous results (Mahoney et al. 1989). A reverse trend is indicated by basalts from 17 to 13°S. However, K/Ti and (La/Sm)_N continuously increase from 23 to 13°S. This opposite behavior indicates a recent decoupling of isotopic and minor element ratios in the mantle between 13 and 17°S. North of 13.5°S (Garrett Fracture Zone), isotopic data show no systematic variation with ridge location and display an overall weaker covariation. The results suggest that the isotopic variations and ridge segmentation appear to be unrelated and that major ridge offsets apparently coincide with changes in mantle melting conditions (P, T, F) (F, degrees of melting). There is no evidence for a systematic relationship between calculated melting conditions and second order ridge segmentation. Our isotopic data provide further evidence for regionally confined chemical variations in the mantle at 5 to 30°S. We interpret the isotopic trends as reflecting melting of distinct smallvolume and old enriched mantle components. In contrast, variations in trace elements are attributed to young mantle differentiation processes.     

Geochronology and Nd-Sr systematics of Lusatian granitoids: significance for the evolution of the Variscan orogen in east-central Europe

A variety of pre-Variscan granitoids and two Variscan monzogranites occurring in the central and western parts of the Lusatian Granodiorite Complex (LGC), Saxonia were dated by the single zircon evaporation method, complemented by whole rock Nd isotopic data and Rb-Sr whole rock and mineral ages. The virtually undeformed pre-Variscan granitoids constitute a genetically related, mostly peraluminous magmatic suite, ranging in composition from two-mica granodiorite, muscovitebearing biotite quartz diorite (tonalite) and granodiorite to biotite granodiorite and monozogranite. ²⁰⁷Pb/²⁰⁶Pb isotopic ratios derived from the evaporation of single zircons separated from 13 samples representing the above rock types display complex spectra which document significant involvement of late Archaean to late Proterozoic continental crust in the generation of the granitoid melts. Mean ²⁰⁷/Pb/²⁰⁶Pb ages for zircons considered to reflect the time of igneous emplacement range between 542 ± 9 and 587 ± 17 Ma, typical of the Cadomian event elsewhere in Europe, whereas zircon xenocrysts yielded ages between 706 ± 13 and 2932 ± Ma. Detrital zircons from greywackes intruded by the granitoids and found as xenoliths in them provided ages between 1136 ± 22 and 2 574 ± Ma. Rb-Sr whole rock data display good to reasonable linear arrays that, with one exception, correspond to the emplacement ages established for the zircons. Two post-tectonic Variscan monzogranites yielded identical ²⁰⁷/Pb/²⁰⁶Pb single zircon ages of 304 ± 14 Ma and record the end of Variscan granitoid activity in the LGC.The variations in Nd and Sr isotopic data of the Cadomian granitoids are consistent with an origin through the melting and mixing of Archean to early Proterozoic crust with variable proportions of mantle-derived, juvenile magmas. Such mixing may have occurred at the base of an active continental margin or in an intraplate setting through plume-related magmatic underplating. The LGC is interpreted here as a Cadomian (Pan-African) terrane distinct from adjacent Variscan and pre-Variscan domains, the origin of which remains obscure and which probably became involved in Palaeozoic terrane accretion late in the Variscan event.     

A Comparison of Unstructured and Structured Principal Component Analyses and their Interpretation

Multivariate analysis is employed to investigate the structure of variations within highly heterogeneous data. Traditionally, principal component analysis (PCA) is run by analyzing the entire wireline log and using PCA scores to characterize variability within and between lithologies. In this paper, we propose a technique using only specific subsets of all well records to quantify reservoir heterogeneity due to second order lithological variability. These subsets are chosen from uniform lithofacies parts of the wireline log in order to reduce the variability in the correlation matrix that otherwise would cause lithological changes. The purpose is to assess the efficiency of structured PCA in analyzing small-scale heterogeneity that is captured by wireline logs but often masked by traditional PCA approaches. This paper shows that a structured PCA procedure based upon special lithological units is superior to an unstructured PCA, when the focus is within lithology variations. This structured procedure is applied to data from the Heidrun field, offshore mid-Norway. The results demonstrate clear benefits from added insight into the variability of a complex fluviodeltaic heterolithic sequence that poses great challenges to hydrocarbon development.     

High-temperature,high-pressure granulites (retrogressed eclogites) in the central region of the Lewisian,NW Scotland: Crustal-scale subduction in the Neoarchaean

Eclogites and associated high-pressure (HP) rocks in collisional and accretionary orogenic belts preserve a record of subduction and exhumation, and provide a key constraint on the tectonic evolution of the continents. Most eclogites that formed at high pressures but low temperatures at > 10–11 kbar and 450–650 °C can be interpreted as a result of subduction of cold oceanic lithosphere. A new class of high-temperature (HT) eclogites that formed above 900 °C and at 14 to 30 kbar occurs in the deep continental crust, but their geodynamic significance and processes of formation are poorly understood. Here we show that Neoarchaean mafic–ultramafic complexes in the central granulite facies region of the Lewisian in NW Scotland contain HP/HT garnet-bearing granulites (retrogressed eclogites), gabbros, lherzolites, and websterites, and that the HP granulites have garnets that contain inclusions of omphacite. From thermodynamic modeling and compositional isopleths we calculate that peak eclogite-facies metamorphism took place at 24–22 kbar and 1060–1040 °C. The geochemical signature of one (G-21) of the samples shows a strong depletion of Eu indicating magma fractionation at a crustal level. The Sm–Nd isochron ages of HP phases record different cooling ages of ca. 2480 and 2330 Ma. We suggest that the layered mafic–ultramafic complexes, which may have formed in an oceanic environment, were subducted to eclogite depths, and exhumed as HP garnet-bearing orogenic peridotites. The layered complexes were engulfed by widespread orthogneisses of tonalite–trondhjemite–granodiorite (TTG) composition with granulite facies assemblages. We propose two possible tectonic models: (1) the fact that the relicts of eclogitic complexes are so widespread in the Scourian can be taken as evidence that a > 90 km × 40 km-size slab of continental crust containing mafic–ultramafic complexes was subducted to at least 70 km depth in the late Archaean. During exhumation the gneiss protoliths were retrogressed to granulite facies assemblages, but the mafic–ultramafic rocks resisted retrogression. (2) The layered complexes of mafic and ultramafic rocks were subducted to eclogite-facies depths and during exhumation under crustal conditions they were intruded by the orthogneiss protoliths (TTG) that were metamorphosed in the granulite facies. Apart from poorly defined UHP metamorphic rocks in Norway, the retrogressed eclogites in the central granulite/retrogressed eclogite facies Lewisian region, NW Scotland have the highest crustal pressures so far reported for Archaean rocks, and demonstrate that lithospheric subduction was transporting crustal rocks to HP depths in the Neoarchaean.     

Magnetic properties and heavy metal content of sanitary leachate sludge in two landfill sites near Bandung,Indonesia

Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10⁻⁸ m³ kg⁻¹. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.     

A combined IR and XRD study of natural well crystalline goethites (α-FeOOH)

Acta Geochimica - Goethite (α-FeOOH) is one of the most abundant minerals on the Earth surface, occurring in temperate, tropical and equatorial climates. Fe in goethite can be substituted by...