Complexity In Southern Africa Research Articles

Detrital zircon geochronology of quartzites from the Central Zone of the Limpopo Complex in southern Africa: Implications for different models and the timing of Zimbabwe Craton–Kaapvaal Craton amalgamation

U–Pb geochronological analyses have been conducted on 765 detrital zircon grains from 11 quartzite samples in the Central Zone of the Limpopo Complex, southern Africa, for constraining the depositional age and provenance of the protolith quartz-sandstone and evaluating the effect of high-grade metamorphism on zircon age data in polymetamorphic terranes. The age data have also been used to evaluate two contrasting tectonic models for the evolution of the complex; collision of the Zimbabwe and Kaapvaal Cratons and diapir-driven intracratonic orogeny, both during the Neoarchean. Magmatic cores of the zircons from the Beit Bridge, Phikwe, and Motloutse Complexes in the Central Zone show a wide age range from 3828 Ma to 1995 Ma. Ages from the Beit Bridge Complex in Zimbabwe (ca. 3.6–3.1 Ga) and South Africa (ca. 3.5–2.4 Ga) are dominantly Paleoarchean to Neoarchean with minor Paleoproterozoic ages. Similar Eoarchean to Neoarchean ages were also obtained from the Phikwe Complex (ca. 3.8–2.6 Ga), whereas ages from the Motloutse Complex are slightly younger (early Mesoarchean to Paleoproterozoic; ca. 3.0–2.4 Ga). Although the age patterns from the three complexes are different, the distribution patterns of discordant and concordant data suggest Eoarchean to Mesoarchean (ca. 3.8–3.1 Ga) ages for magmatic cores of detrital zircon grains. Homogeneous zircon rims around magmatic cores gave metamorphic ages of ca. 2.61 Ga and ca. 2.27–2.02 Ga, probably formed by Neoarchean and Paleoproterozoic high-grade metamorphisms. Similar Neoarchean (ca. 2.7–2.6 Ga) and Paleoproterozoic concordant ages obtained from magmatic zircon cores are interpreted as reset ages due to Pb loss during the metamorphic events. The smaller peak of the Paleoproterozoic age population compared to that of the Neoarchean age data suggests the dominant high-grade metamorphism of the Central Zone took place at ca. 2.7–2.6 Ga, either by collision of the Zimbabwe and Kaapvaal Cratons or by diapir-driven intracratonic orogeny. Therefore, cratonization of the Azanian (Kalahari) Craton probably occurred before ca. 2.6 Ga. Based on the age patterns, the depositional age of the protolith quartz-rich sandstone is constrained as 3.1–2.7 Ga. The provenance of the Paleoarchean to Mesoarchean (3.6–3.1 Ga) detrital zircons has been inferred as orthogneisses and granitoids of the southern Zimbabwe Craton (e.g., Tokwe Segment). The oldest Eoarchean detrital zircon (3828 Ma) obtained from the Phikwe Complex suggests the presence of unknown older crust in this provenance.

Petrology and geochronology of sapphirine‐bearing granulites from the Limpopo Complex in eastern Botswana: Implications for Palaeoproterozoic long‐lived high‐pressure/ultrahigh‐temperature metamorphism and rapid exhumation

The Limpopo Complex in southern Africa is a classic example of Neoarchean collisional orogens with a Palaeoproterozoic thermal overprint. We report new petrological, pressure–temperature (P–T), and geochronological data of sapphirine‐bearing Mg–Al‐rich and pelitic granulites from a metasupracrustal unit (the Beit Bridge Complex [BBC]) in the eastern part of Botswana to constrain its P–T–time evolution. Textural observations and phase equilibria modelling of the peak mineral assemblage of Mg–Al‐rich granulites (K‐feldspar + orthopyroxene [Opx2; Al2O3 up to 8.8 wt.%] + sillimanite [Sil2] + quartz + rutile + biotite [Bt2] + inferred melt) in the NCKFMASHTO system recorded a peak metamorphic condition of >930°C and > 10.3 kbar. A pelitic granulite recorded consistent P–T conditions of 960–980°C and > 10.3 kbar, indicating high‐pressure (HP) and ultrahigh‐temperature (UHT) metamorphism for the BBC in Botswana. Post‐peak retrograde conditions were obtained based on the stability of sapphirine + cordierite symplectite assemblage in the Mg–Al‐rich rocks (820–860°C and 6.4–7.0 kbar) and orthopyroxene [Opx3] + cordierite symplectite assemblage in the pelitic granulite (830–930°C and 4.3–5.8 kbar), indicating near‐isothermal decompression after the peak HP–UHT metamorphism along a clockwise P–T path. Similar HP–UHT metamorphism followed by a near‐isothermal decompression along a clockwise P–T path was reported from different regions of the BBC in South Africa and Zimbabwe (P > 14 kbar and ~1,000°C based on the stability fields of magnesian staurolite and sapphirine + quartz assemblage), although the peak P–T condition is slightly lower in Botswana. Monazite grains with patchy zoning show isochron ages of 2,115 ± 77 Ma for Th‐poor domains, and 2,058 ± 40 Ma and 2,033 ± 34 Ma for Th‐rich domains. Similar ages were obtained from zircon U–Pb geochronology as 2,232–2,135 Ma and 2,010 ± 19 Ma (Th/U = 0.05–0.26). The younger ages (2.0 Ga) probably indicate the timing of near‐peak high‐grade event, while the older ages might indicate a thermal event during the prograde heating stage. The P–T conditions and zircon/monazite ages suggest Palaeoproterozoic long‐lived metamorphism associated with intracontinental transpressional tectonics related to Palaeoproterozoic orogenic events around the united Zimbabwe–Kaapvaal Craton.

How many species does the Psammobates tentorius (tent tortoise) species complex (Reptilia, Testudinidae) comprise? A taxonomic solution potentially applicable to species complexes

We examined morphometric differentiation in the highly polymorphic and taxonomically confusing Psammobates tentorius (tent tortoise) species complex in southern Africa, using morphological data together with previously published DNA sequence and microsatellite DNA data. We used the approximate Bayesian computation-based simulation analysis to test alternative phylogenetic hypotheses supported by different markers, using a total evidence dataset for the tent tortoise species complex. The results supported a scenario, which is better and more inclusive in explaining its genealogical history. Our total evidence-based Bayesian BPP species delimitation analysis (mtDNA + nDNA + morphology) suggested a seven species scheme should be applied to the P. tentorius species complex. Nonetheless, based on comparative results obtained from sequence, microsatellite, ecological niche, and morphological data, a four-species scheme (among the seven mtDNA clades) appears to be the best taxonomic solution for the systematic puzzle of the P. tentorius species complex, namely, “C1 + C4 + C5 + C7,” “C3,” “C2,” and “C6.” We detected several possible hybridizations between C1 and C2 in their intergradation zone that confirmed the possible cross-over between them. Lastly, we provide a summarized flow chart of the analyses carried out for determining the optimal taxonomic solution for this phenotypically difficult group, as it may also be useful for resolving complex taxonomic issues in other species groups.

Deep genetic and morphological divergence in the Hippopotamyrus ansorgii species complex (Teleostei: Mormyridae) in southern Africa.

The present study used molecular and morphological approaches to investigate hidden diversity within the Hippopotamyrus ansorgii species complex in southern Africa. Phylogenetic reconstructions and three species delimitation methods based on two mitochondrial markers (cytochrome b and cytochrome oxidase I) and one nuclear marker (S7) revealed 12 Molecular Operational Taxonomic Units (MOTUs), with two of them representing two recently described species, Hippopotamyrus longilateralis and Hippopotamyrus szaboi. The highest diversity occurred in the Kwanza River system, which contained five MOTUs, and the Upper Zambezi River system that had two MOTUs. Five other river systems contained a single MOTU each. A major impediment to the review of this complex has been the uncertainty surrounding the type locality of the specimens that were used for the description of H. ansorgii. The present study has, through a careful examination of published literature and synthesis of information on the travel activities of Dr. William Ansorge who collected the specimens, identified the Kwanza River system as the most plausible source of the syntypes. The resolution of the type locality of H. ansorgii facilitates future work on the review of this complex which is critical for providing reliable biodiversity estimates, identifying effective conservation management strategies and understanding the evolutionary history and biogeographic patterns of the fishes of this region.

Climatic and topographic changes since the Miocene influenced the diversification and biogeography of the tent tortoise (Psammobates tentorius) species complex in Southern Africa

BackgroundClimatic and topographic changes function as key drivers in shaping genetic structure and cladogenic radiation in many organisms. Southern Africa has an exceptionally diverse tortoise fauna, harbouring one-third of the world’s tortoise genera. The distribution of Psammobates tentorius (Kuhl, 1820) covers two of the 25 biodiversity hotspots in the world, the Succulent Karoo and Cape Floristic Region. The highly diverged P. tentorius represents an excellent model species for exploring biogeographic and radiation patterns of reptiles in Southern Africa.ResultsWe investigated genetic structure and radiation patterns against temporal and spatial dimensions since the Miocene in the Psammobates tentorius species complex, using multiple types of DNA markers and niche modelling analyses. Cladogenesis in P. tentorius started in the late Miocene (11.63–5.33 Ma) when populations dispersed from north to south to form two geographically isolated groups. The northern group diverged into a clade north of the Orange River (OR), followed by the splitting of the group south of the OR into a western and an interior clade. The latter divergence corresponded to the intensification of the cold Benguela current, which caused western aridification and rainfall seasonality. In the south, tectonic uplift and subsequent exhumation, together with climatic fluctuations seemed responsible for radiations among the four southern clades since the late Miocene. We found that each clade occurred in a habitat shaped by different climatic parameters, and that the niches differed substantially among the clades of the northern group but were similar among clades of the southern group.ConclusionClimatic shifts, and biome and geographic changes were possibly the three major driving forces shaping cladogenesis and genetic structure in Southern African tortoise species. Our results revealed that the cladogenesis of the P. tentorius species complex was probably shaped by environmental cooling, biome shifts and topographic uplift in Southern Africa since the late Miocene. The Last Glacial Maximum (LGM) may have impacted the distribution of P. tentorius substantially. We found the taxonomic diversify of the P. tentorius species complex to be highest in the Greater Cape Floristic Region. All seven clades discovered warrant conservation attention, particularly Ptt-B–Ptr, Ptt-A and Pv-A.

Festuca drakensbergensis (Poaceae): A common new species in the F. caprina complex from the Drakensberg Mountain Centre of Floristic Endemism, southern Africa, with key and notes on taxa in the complex including the overlooked F. exaristata.

We present taxonomic notes on the Festuca caprina complex from southern Africa that includes description and illustration of the new species F. drakensbergensis from the Drakensberg Mountain Centre of Floristic Endemism of South Africa and Lesotho. Festuca drakensbergensis can be differentiated from F. caprina s.l. by forming lax short tufts with extravaginally-branching tillers and lateral-tending cataphyllous shoots or rhizomes present, basal foliage reaching < ½ the length of the culms, with generally shorter leaves and shorter anthers, 0.8−1.6(−1.8) mm long. The species also differs from the overlooked species F. exaristata – currently known from two collections from Lesotho − by its fibrous basal sheaths, usually sharp, keel-like leaf blade midrib, drooping panicle with lightly to densely scabrous pendent panicle branches, longer lemmas, 4.5−5.8 mm long, with awns usually present, 0.5–3 mm long, ovary apices sparsely to densely hairy and anthers 0.8−1.6(−1.8) mm long. Taxonomic notes on the different taxa of the F. caprina complex in southern Africa are also provided, including images, key, and lectotypification of F. caprina var. curvula. This research adds a further two endemic species (F. drakensbergensis and F. exaristata) and two endemic varieties (F. caprina var. irrasa and F. caprina var. macra) to the Drakensberg Mountain Centre of Floristic Endemism.

A taxonomic revision of the south-eastern dragon lizards of the Smaug warreni (Boulenger) species complex in southern Africa, with the description of a new species (Squamata: Cordylidae).

A recent multilocus molecular phylogeny of the large dragon lizards of the genus Smaug Stanley et al. (2011) recovered a south-eastern clade of two relatively lightly-armoured, geographically-proximate species (Smaug warreni (Boulenger, 1908) and S. barbertonensis (Van Dam, 1921)). Unexpectedly, S. barbertonensis was found to be paraphyletic, with individuals sampled from northern Eswatini (formerly Swaziland) being more closely related to S. warreni than to S. barbertonensis from the type locality of Barberton in Mpumalanga Province, South Africa. Examination of voucher specimens used for the molecular analysis, as well as most other available museum material of the three lineages, indicated that the ‘Eswatini’ lineage—including populations in a small area on the northern Eswatini–Mpumalanga border, and northern KwaZulu–Natal Province in South Africa—was readily distinguishable from S. barbertonensis sensu stricto (and S. warreni) by its unique dorsal, lateral and ventral colour patterns. In order to further assess the taxonomic status of the three populations, a detailed morphological analysis was conducted. Multivariate analyses of scale counts and body dimensions indicated that the ‘Eswatini’ lineage and S. warreni were most similar. In particular, S. barbertonensis differed from the other two lineages by its generally lower numbers of transverse rows of dorsal scales, and a relatively wider head. High resolution Computed Tomography also revealed differences in cranial osteology between specimens from the three lineages. The ‘Eswatini’ lineage is described here as a new species, Smaug swazicus sp. nov., representing the ninth known species of dragon lizard. The new species appears to be near-endemic to Eswatini, with about 90% of its range located there. Our study indicates that S. barbertonensis sensu stricto is therefore a South African endemic restricted to an altitudinal band of about 300 m in the Barberton–Nelspruit–Khandizwe area of eastern Mpumalanga Province, while S. warreni is endemic to the narrow Lebombo Mountain range of South Africa, Eswatini and Mozambique. We present a detailed distribution map for the three species, and a revised diagnostic key to the genus Smaug.

Three tier transition of Neoarchean TTG-sanukitoid magmatism in the Beit Bridge Complex, Southern Africa

Neoarchean TTG-sanukitoid associations of contrasting scales occur within the Beit Bridge Complex terrane of the Limpopo Complex in southern Africa. These include the smaller ~2.65–2.63Ga Avoca granitoid and the voluminous ~2.73–2.64Ga Alldays granitoid. This study characterizes the wide compositional spectrum preserved in these two granitoids. The elliptical Avoca pluton consists of a biotite-amphibole-orthopyroxene±clinopyroxene-bearing core that is dominantly trondhjemite with less dominant tonalite and granodiorite variants, and a thin amphibole-biotite-bearing granite rim, with local occurrence of two-pyroxene-bearing metabasite boudins. While both the core and rim rocks exhibit a linear fabric, the granite in addition preserves a penetrative foliation. Field relations of granite enclaves in the core rocks together with available ages indicate that the core rocks intruded the granite. The foliated biotite±amphibole-bearing Alldays granitoid contains inclusions of older supracrustals and rocks of the Messina layered intrusion, and is widely distributed. Compositionally, it include tonalites and granodiorites and to a lesser extent trondhjemites. Both the Avoca core and rim rocks are characterized by difference in mineral chemistry, with the mafic minerals Mg-rich in the TTG core, while they are Fe-rich in the granite and metabasite. In comparison, biotite is Mg-rich and amphibole is Fe-rich in the Alldays granitoid.Two groups of Alldays TTG can be delineated in terms of whole-rock geochemical characteristics, and are comparable to the low- to medium-pressure TTG groups delineated by Moyen (2011), while the Avoca TTG is similar to the high-pressure TTG group. The lowest silica samples from each group of granitoid have geochemical characteristics comparable to Archean sanukitoids, with those from the Avoca granitoid similar to low-Ti sanukitoids, and those from the Alldays granitoid similar to low-Ti and high-Ti sanukitoids. Separate petrogenetic models are suggested for different phases of the Avoca core, with the trondhjemite-tonalites considered as high-pressure melts of metabasalt, while the granodiorite with lower SiO2 content, higher K2O and MgO contents, and higher incompatible element contents, than the trondhjemite-tonalites, is a product of hybridization of earlier TTG melts and peridodite. Granite from the Avoca rim are low-pressure melts of pre-existing crustal lithologies. The two groups of Alldays TTG with lower Sr/Y ratios than the Avoca TTG are considered as low- to medium-pressure melts of metabasalt, whose progressive interaction with peridotitic mantle at shallower angles account for the unique composition of Alldays low-Ti and high-Ti sanukitoids. Taken together with their spatial and temporal transition from southeastern (~2.73–2.72Ga; low-pressure TTG-low-Ti sanukitoid) to central (~2.65–2.64Ga; medium-pressure TTG-high-Ti sanukitoid) to northwestern (~2.63Ga; high-pressure TTG-low-Ti sanukitoid) parts of the Beit Bridge Complex, the three tier transition of TTG-sanukitoid magmatism argues for the southern margin of the Beit Bridge Complex to represent an active arc in the Neoarchean.

Relocating Ingombe Ilede in the history of south-central Africa

We thank the four commentators for adding new dimensions and important data relevant to interpreting the new Ingombe Ilede dates. These contribute to the recent wave of reassessments and critiques of earlier interpretations and frameworks for the development of trade and complexity in southern Africa. Such reconsiderations are made possible by more sophisticated and precise radiocarbon dating, expanded investigation of both new and previously excavated sites, and by the use of chemical analyses to identify differently sourced groups of glass beads and metals (e.g. Pikirayi 2009; Robertshaw et al. 2010; Chirikure et al. 2013, 2014, 2016; Koleini et al. 2016).

The &lt;i&gt;Rhynchosia totta&lt;/i&gt; complex (Phaseoleae, Fabaceae) in Southern Africa, including the description of a new variety and new species

Background: The Rhynchosia totta complex is one of three taxonomically complicated African groups in the genus Rhynchosia. Numerous southern African species and infraspecific taxa (at least 19 names, 17 species and 2 varieties) have been described by various authors in the past, but were later reduced into synonymy with R. totta. Currently, only the typical variety is recognised in Southern Africa.Objectives: To investigate and update the circumscription of the taxa within the R. totta complex in southern Africa and to update their synonymies and distribution ranges. Methods: Specimens of R. totta at GRA, JRAU, K, NH and PRE were studied and compared, and measurements of characters recorded. Populations were also observed during field studies.Results: The examination of numerous specimens, as well as field investigations, has prompted the recognition of four varieties (one described here as new: R. totta var. longicalyx) and a new species (R. pedunculata) in southern Africa.Conclusions: A great variation in leaf structure and vestiture occurs within the R. totta complex, with the extreme forms easily recognisable. However, the total number of varieties are limited to four [R. totta vars. totta, longicalyx, rigidula and venulosa] and a new species described to accommodate specimens with a distinctly prostrate habit and upwardly directed leaves.

Decisive Evidence for Multidirectional Evolution of Sociopolitical Complexity in Southern Africa

While pioneers of archaeology in any given region have established the foundations of the discipline, their views have not remained unchanged in places such as Europe, North America and Australasia. In these regions, successive generations of researchers changed the direction of their work based not just on new observations but also in light of new methods and theories. For example, the idea of a Bronze Age revolution popularised by V. G. Childe in Europe was superseded by multiple alternatives over the years. In southern African Iron Age studies, John Schofield, Gertrude Caton-Thompson, Roger Summers, Keith Robinson and Peter Garlake created an impressive platform upon which successors could build. Confronting firm disapproval from more experienced researchers in the early 1980s, Huffman speculated that the evolution of sociopolitical complexity in our region was a linear relay from Mapungubwe to Khami via Great Zimbabwe. This position was sustained as the conventional wisdom largely, we argue, because no new research was being carried out in key areas of the region, and too few students, in particular African ones, were being trained to expand the focus of investigation. Here, we present new data to support our argument, that the pathway to sociopolitical complexity in southern Africa was multilinear. We propose looking forward rather than back, and to continue to seek the exposure of scales of interaction between multiple but chronologically overlapping entities associated with the rise of sociopolitical complexity in southern Africa.

Social Complexity in Southern Africa

Comprehensive evidence has shown that Mapungubwe was the centre of the first state in southern Africa. Recently, some archaeologists have argued that the distribution of artefacts, stone walling, and hilltop locations suggests multiple and earlier centres. A close examination of these data, however, does not support the claims. Counter evidence involving ceramics, rainmaking vs. residence, radiocarbon dates, and field data continues to support the temporal primacy of Mapungubwe and the Shashe-Limpopo Valley.

Zimbabwe culture before Mapungubwe: new evidence from Mapela Hill, South-Western Zimbabwe.

Across the globe, the emergence of complex societies excites intense academic debate in archaeology and allied disciplines. Not surprisingly, in southern Africa the traditional assumption that the evolution of socio-political complexity began with ideological transformations from K2 to Mapungubwe between CE1200 and 1220 is clouded in controversy. It is believed that the K2−Mapungubwe transitions crystallised class distinction and sacred leadership, thought to be the key elements of the Zimbabwe culture on Mapungubwe Hill long before they emerged anywhere else. From Mapungubwe (CE1220–1290), the Zimbabwe culture was expressed at Great Zimbabwe (CE1300–1450) and eventually Khami (CE1450–1820). However, new fieldwork at Mapela Hill, when coupled with a Bayesian chronology, offers tremendous fresh insights which refute this orthodoxy. Firstly, Mapela possesses enormous prestige stone-walled terraces whose initial construction date from the 11th century CE, almost two hundred years earlier than Mapungubwe. Secondly, the basal levels of the Mapela terraces and hilltop contain élite solid dhaka (adobe) floors associated with K2 pottery and glass beads. Thirdly, with a hilltop and flat area occupation since the 11th century CE, Mapela exhibits evidence of class distinction and sacred leadership earlier than K2 and Mapungubwe, the supposed propagators of the Zimbabwe culture. Fourthly, Mapungubwe material culture only appeared later in the Mapela sequence and therefore post-dates the earliest appearance of stone walling and dhaka floors at the site. Since stone walls, dhaka floors and class distinction are the essence of the Zimbabwe culture, their earlier appearance at Mapela suggests that Mapungubwe can no longer be regarded as the sole cradle of the Zimbabwe culture. This demands not just fresh ways of accounting for the rise of socio-political complexity in southern Africa, but also significant adjustments to existing models.

New Pathways of Sociopolitical Complexity in Southern Africa

Much is known about the economy and spatial organization of Zimbabwe culture entities of Mapungubwe, Great Zimbabwe and Khami but less in terms of their origins and relationship with each other. Based on little tangible evidence, it is believed and widely accepted that the societies based at Mapungubwe (AD 1220-1290), Great Zimbabwe(AD1300-1450) andKhami (AD1450-1820) rose, developed and eclipsedin tandem. A recent reexamination of the relationship between these settlements and related ones using local ceramics, imported artefacts, stone architecture and Bayesian modelling suggests this may not have been the case. The synthesis proffered revelations which temper the widely acceptedassumptionthatsociopoliticalcomplexity insouthern Africa began in the Shashi-Limpopo Valley before anywhere else in the region. Firstly, there are numerous Zhizo and Leopard's Kopje sites that predate Mapungubwe but contain prestige goods and stone structures dating from the late first millennium AD. Secondly, material culture studies and modelled radiocarbon dates indicate that Great Zimbabwe evolved out of Gumanye while Khami, like Mapungubwe, may have developed out of the Leopard's Kopje. In fact, Great Zimbabwe was already a place of importance when Mapungubwe collapsed. Thirdly, Khami and Great Zimbabwe overlapped for over a century, before the latter buckled. Therefore, the evolution of sociopolitical complexity in southern Africa may have followed trajectories that are different from what the current understanding implies. Resume Nous savons beaucoup de choses a propos de l'organisation spatiale et de l'economie des entites culturelles Zimbabweennes de Mapungubwe, Great Zimbabwe et Khami, mais peu sur leurs origines et leurs relations. Selon le peu de donnees disponibles, Mapungubwe (1220-1290 ap. J-C), Great Zimbabwe (1300-1450 ap. J-C) et Khami

The International Food Safety Complex in Southern Africa: cooperation or competition?

The article seeks to contribute to discussions about international institutional complexes, in particular how they emerge and form functional niches. Testing the premise that competition between international institutions guides functional niche selection, the International Food Safety Complex (IFSC) is characterised and examined in light of the experience of Southern Africa. Institutional competition is shown not to be a necessary precondition for functional niche selection; rather, cooperation can also be a starting point. Related to whether competition or cooperation win out are the timing of and absolute demand for the international institutional complex. The final section looks at the impact of the structure and function of the IFSC on building food safety regulation in the Southern African region. A single case study of South Africa offers some insight into the opportunities and challenges that exist in the African region.

Hafnium isotope record of the Ancient Gneiss Complex, Swaziland, southern Africa: evidence for Archaean crust–mantle formation and crust reworking between 3.66 and 2.73 Ga

Abstract: Combined U–Pb and Lu–Hf isotope analyses of zircons from 16 tonalite–trondjemite–granodiorite (TTG) gneiss and granite samples from Swaziland reveal that the oldest rocks of the Ancient Gneiss Complex in southern Africa formed by reworking of Early Archaean or perhaps Late Hadean crust at 3.66 Ga, and that new crust was extracted from a depleted mantle source during Palaeoarchaean events between 3.54 and 3.32 Ga. This interpretation is supported by eHf t of −1.6 ± 2.0 obtained from 3.66 Ga TTG gneisses, corresponding to hafnium model ages between 3.77 ± 0.18 Ga, for a presumed Hadean–Early Archaean chondritic mantle, and 4.08 ± 0.18 Ga, for a presumed Hadean depleted mantle reservoir, with the first model age being the most likely in the light of recent data from worldwide sources. Furthermore, it is reflected by superchondritic eHf t up to +2.2 ± 2.0 for TTGs formed at 3.54, 3.45 and 3.32 Ga. The new datasets additionally show that the Palaeoarchaean crust formed between 3.54 and 3.32 Ga was intensely reworked afterwards, without significant addition of depleted mantle derived material, during orogenic and intracratonic melting processes at 3.23, 3.1 and 2.7 Ga. This is well reflected by an array of decreasing eHf t from +2.2 to −7.2 between 3.3 and 2.7 Ga, which can be forced by 176 Lu/ 177 Hf of 0.0113, which is similar to that of present-day average continental crust, and might result from lower crust zircon fractionation during Archaean crust reworking. Supplementary material: Results of in situ U–Pb and Lu–Hf isotope zircon analyses and concordia diagrams are available at www.geolsoc.org.uk/SUP18465.

Mapungubwe and Great Zimbabwe: The origin and spread of social complexity in southern Africa

Stratified societies in southern Africa first developed in the Shashe–Limpopo Basin. As is well known, rank-based society at K2 developed into class distinction at Mapungubwe. The transfer of this new social organisation to Great Zimbabwe has received less attention. New research on rainmaking practices suggests that a Mapungubwe dynasty introduced class structures at Great Zimbabwe. Poor climatic conditions at the end of the 13th century undermined sacred leaders at Mapungubwe itself, and while vulnerable, the elite at Great Zimbabwe took over the important gold and ivory trade. Among other things, the new elite used the unique Zimbabwe birdstones to establish their legitimacy.

A survey of blood lead levels among young Johannesburg school children

Studies conducted around the world have established beyond doubt that elevated childhood blood lead levels may lead to detrimental health effects. Research has shown that certain groups of South African children are at particular risk of elevated blood lead levels. Johannesburg is the largest urban complex in southern Africa, with a population of around 3 million and extensive industrial and manufacturing activity. Among the challenges posed in the city are rapid urbanization, extensive poverty, and inequity. Little information on the blood lead distribution of Johannesburg children is available. This study was undertaken to determine blood lead levels among children living in three areas of Johannesburg: inner city suburbs and the low-income townships of Alexandra and Westbury to the north and west of the city center, respectively. The results indicated that blood lead levels ranged from 6 to 26 μg/dL, with a mean level of 11.9 μg/dL. The blood lead levels of 78% of children equaled or exceeded 10 μg/dL, the current international action level. Maternal educational status, the presence of smokers in the home, and living in an informal dwelling were among the factors associated with elevated blood lead levels.

Revision of the &lt;i&gt;Tarchonanthus&lt;/i&gt; camphoratus complex (Asteraceae-Tarchonantheae) in southern Africa

The Tarchonanthus camphoratus L. complex in southern Africa is revised. Five species are recognized on the grounds of differences in synflorescences, flowering times, leaf shape and margin, and distribution. Two names. T. minor Less, and T. ohovatus DC., are resurrected and two new species. T. littoralis P.P.J.Herman and T. parvicapitulatus PP.J.Herman. are described. A key, lull descriptions of each taxon and distribution data are presented.

Taxonomic status of the Patella miniata species complex (Mollusca: Gastropoda) in southern Africa

The species boundaries between members of the southern African ‘Patella miniata’ species complex (Patella miniata miniata, P. miniata sanguinans and P. compressa) are poorly defined on morphological grounds. Doubt also exists whether all populations of P. miniata miniata constitute a single taxon, with ‘P. cf. miniata’ having uncertain affinities. The status of P. adansonii (known only from shells) is also obscure. Protein gel electrophoresis was employed to resolve these taxonomic uncertainties. In addition, a population of P. safiana from southern Angola was included in the study as a reference population. Electrophoretic analysis of 16 enzyme loci revealed four distinctive groupings. All populations of P. miniata miniata and P. cf. miniata proved closely related and separated from P. compressa populations at I=0.85; the P. miniata sanguinans populations clustered out at I=0.79; and P. safiana separated at I=0.69. Phylogenetic analyses, using P. safiana as an outgroup, indicated that P. miniata miniata, P. miniata sanguinans and P. compressa form a closely related monophyletic group in which P. miniata miniata and P. compressa are more closely related to each other than either one of them is to P. miniata sanguinans. Morphological analyses (shells, radula, sperm microstructure) revealed differences that mirrored the differences detected by the allozymes. Thus, it was concluded that P. miniata sanguinans and P. miniata miniata warrant full specific status and we therefore raise the former to P. sanguinans. Patella miniata miniata and P. cf. miniata are geographic variants of the same species, P. miniata, and P. adansonii is sunk within this species. Furthermore, the suggestion that P. miniata and P. compressa may be ecomorphs of the same species are not supported and both warrant specific status. Thus, the ‘Patella miniata’ species complex in southern Africa is a closely related monophyletic group of three species, with P. miniata and P. compressa being more closely related to each other than either one is to P. sanguinans.