Benjamin Mapani | University of Namibia (original) (raw)

Papers by Benjamin Mapani

Environment International, 2019

Ore mining and processing in semi-arid areas is responsible for the generation of metal(loid)-con... more Ore mining and processing in semi-arid areas is responsible for the generation of metal(loid)-containing dust, which is easily transported by wind to the surrounding environment. To assess the human exposure to dustderived metal(loid)s (As, Cd, Cu, Pb, Sb, Zn), as well as the potential risks related to incidental dust ingestion, we studied mine tailing dust (n = 8), slag dust (n = 5) and smelter dust (n = 4) from old mining and smelting sites in northern Namibia (Kombat, Berg Aukas, Tsumeb). In vitro bioaccessibility testing using extraction in simulated gastric fluid (SGF) was combined with determination of grain-size distributions, chemical and mineralogical characterizations and leaching tests conducted on original dust samples and separated PM 10 fractions. The bulk and bioaccessible concentrations of the metal(loid)s were ranked as follows: mine tailing dusts < slag dusts ≪ smelter dusts. Extremely high As and Pb bioaccessibilities in the smelter dusts were caused by the presence of highly soluble phases such as arsenolite (As 2 O 3) and various metal-arsenates unstable under the acidic conditions of SGF. The exposure estimates calculated for an adult person of 70 kg at a dust ingestion rate of 50 mg/day indicated that As, Pb (and also Cd to a lesser extent) grossly exceeded tolerable daily intake limits for these contaminants in the case of slag and smelter dusts. The high risk for smelter dusts has been acknowledged, and the safety measures currently adopted by the smelter operator in Tsumeb are necessary to reduce the staff's exposure to contaminated dust. The exposure risk for the local population is only important at the unfenced disposal sites at Berg Aukas, where the PM 10 exhibited high levels of bioaccessible Pb. especially high in arid or semi-arid areas, where the total respirable aerosols (PM 10 ; i.e., particulate matter of grain sizes equal to 10 μm or less) significantly exceed permissible levels as defined by environmental agencies and health organizations (US EPA, WHO) (Ghorbel et al., 2010; Csavina et al., 2012; Thomas et al., 2018). For example, Ojelede et al. (2012) reported that the PM 10 concentration was > 2000 μg/m 3 at higher wind speeds in the vicinity of a mine tailing site in South Africa; this value far exceeds the 24-h limit value of 150 μg/m 3 stipulated by US EPA. Apart from the consumption of contaminated water and food, the incidental ingestion and/or inhalation of dust and soil particles

EGU General Assembly Conference Abstracts, Apr 1, 2019

EGU General Assembly Conference Abstracts, Apr 1, 2016

Journal of Cleaner Production, Dec 1, 2022

Journal of African Earth Sciences, Jun 1, 2021

Abstract This work investigates Mesoproterozoic volcanic rocks of the Haiber Flats, Barby, Welver... more Abstract This work investigates Mesoproterozoic volcanic rocks of the Haiber Flats, Barby, Welverdiend and Kairab Formations, and associated intrusive rocks in the Konkiep Terrane. Various correlations have been made in the past and recent dating work yields contrasting ages. U–Pb dating of zircons is applied in combination with Sm–Nd and Lu–Hf isotopes to determine the age, assess correlation and ascertain the much-debated tectonic setting . Ion probe U–Pb zircon dating yields ages of 1218 ± 5 Ma, 1212 ± 4 Ma and 1212 ± 5 Ma (all errors 2σ) for three samples of the Haiber Flats Formation and 1219 ± 13 Ma, 1215 ± 19 Ma for the Barby Formation. The ages obtained for the Barby Formation agree with the 1217 ± 2 Ma and 1214 ± 5 Ma ages reported from previous investigations. Rocks mapped as the supposedly older Kairab rhyolite and felsic tuff gave younger ages of 1220 ± 4 Ma and 1222 ± 10 Ma, respectively, which are coeval with the Barby and Haiber Flats Formations. Two Gorab Gabbro samples, previously mapped as Kairab Formation, yield ages of 1341 ± 8 Ma and 1336 ± 8 Ma. These older ages are within error of two Welverdiend Formation samples which gave ages of 1344 ± 6 Ma and 1337 ± 9 Ma, and the formation was previously dated in the type area at 1327 ± 10 Ma. These ages confirm the reassignment of rocks originally mapped as tholeiitic Barby Formation into the Welverdiend Formation, north of a newly identified stratigraphic hiatus corresponding to the geophysically defined Wereldend Lineament . Sm–Nd and Lu–Hf isotopic signatures for the Barby, Haiber Flats and coeval Kairab samples indicate that they are co-magmatic and derived from partly depleted mantle contaminated by older crust. TDM model ages of these samples range from 2.5 to 1.5 Ga with a major 2.2 to 1.8 Ga group. This suggests that the older crustal component was Paleoproterozoic but included some Archean material. The Welverdiend Formation and Gorab Gabbros show similarity in age, Sm–Nd and Lu–Hf characteristics and were probably derived from partially depleted mantle, or from a well-homogenised mixture of depleted mantle and older crust. REE diagrams indicate enrichment in LREE (La–Gd) and a flat HREE pattern (Tb to Lu). On spidergrams, most samples are characterised by negative Nb–Ta anomalies and positive K and Pb anomalies which indicate a subduction-related setting (with positive Sr anomaly) or a reworked crustal origin. The similarity in ages, isotopic signatures and geochemistry confirms the correlation of the Barby and Haiber Flats Formation.

Applied Geochemistry, Mar 1, 2020

Abstract The historical mining and processing of Zn–Pb–V ores at Berg Aukas in northern Namibia l... more Abstract The historical mining and processing of Zn–Pb–V ores at Berg Aukas in northern Namibia left large amounts of various wastes. This study focuses on the mineralogical and geochemical investigation of the V-rich slags issued from the processing of the local ores in the Waelz kiln, which was operational between 1968 and 1980 and left ca. 500 kt of slag deposited on the adjacent dump. A combination of mineralogical methods, bulk chemistry, leaching tests and speciation-solubility modeling was used to understand the binding of the major contaminants (Zn, Pb, V) in the solid phase and their potential release under the changing environmental conditions. The average concentrations of the metal(loid) contaminants in the slags are 3.78 wt% Zn, 3370 mg/kg Pb, 5880 mg/kg V, 767 mg/kg Cu, 578 mg/kg As and 92 mg/kg Sb. The mineralogy is dominated by high-temperature silicates (clinopyroxene, melilite, olivine-family phases) and Zn-bearing phases (willemite, zincite). All the primary silicates and oxides are Zn-rich, but vanadium is mainly concentrated in clinopyroxene (up to 5 wt% V2O3). Metallic Fe inclusions, formed under highly reducing conditions in the kiln, are highly weathered. Secondary Fe(III) (hydr)oxides, corresponding to the main weathering products in the slag, efficiently sequester the metal(loid)s (mainly As and Sb). The EU regulatory leaching tests indicated that the release of the metal(loid) contaminants is quite low at the natural pH (deionized water extract: 8.5–10.4) obtained by extraction in the deionized water and only Sb in all the slag samples exceeds the EU limits for the landfilling of inert waste. The pH-static leaching tests revealed up to 5 orders of magnitude higher release of Pb and Zn under acidic conditions (up to 38% and 63% of their total concentration, respectively), compared to the natural pH. In contrast, V exhibits relatively flat pH-dependent leaching patterns with only

Review of Palaeobotany and Palynology, Jun 1, 2018

Understanding vegetation-modern pollen relationships is essential to provide confidence in fossil... more Understanding vegetation-modern pollen relationships is essential to provide confidence in fossil pollen reconstructions of long-term vegetation changes in savanna ecosystems. In this paper we compare the taxonomical composition and the diversity (Hill N0, N1, N2) of vegetation and modern pollen along precipitation and local grazing-intensity gradients in Namibian savannas. Modern pollen was extracted from surface soil samples collected from 5x5 m plots distributed along four 500 m gradients. Vegetation was surveyed in each plot. The results show a high correspondence between vegetation and pollen data in terms of composition. Precipitation and grazing explain a significant although low proportion of compositional change in the vegetation and pollen spectra. We identified pollen taxa as indicators of grazing pressure such as Limeum, Alternanthera, and particularly Tribulus. Correspondence between vegetation and pollen data in terms of taxa richness (N0) is limited, probably because of the influence of landscape heterogeneity and openness, as well as low pollen concentrations. In contrast, the effective numbers of common and dominant taxa (N1, N2) are consistent among the different datasets. We conclude that in spite of limitations, modern pollen

Chemical Geology, Jun 1, 2019

The dynamics of Cu and Pb were studied in eight soil profiles (Luvisols, Chernozems), located at ... more The dynamics of Cu and Pb were studied in eight soil profiles (Luvisols, Chernozems), located at various distances from the tailing dams near a closed Cu-Pb-(Zn)-Ag mine at Kombat (Namibia) by a combination of isotope and elemental studies, leaching techniques and speciation modelling. Tailings, soils and bedrocks were analysed for the bulk Cu and Pb concentrations, for their chemical forms using the sequential extraction procedure and for the isotope compositions of Cu (δ 65 Cu) and Pb (206 Pb/ 207 Pb, 208 Pb/ 206 Pb). In spite of the differences in the contamination of the studied profiles by tailing dust, both soil types exhibit characteristic trends in the behaviour of metals and distribution of their isotopes. While most Luvisols exhibit an increase in the metal content towards depth in the profile, Chernozems exhibit the opposite trend (decrease in metal content with depth) or similar contents in the whole profile. Luvisols were mostly characterized by changing δ 65 Cu values as a function of depth. The value of δ 65 Cu decreases with depth to the Bt horizon and then the δ 65 Cu value increases with increasing depth. Chernozems mostly yielded uniform Cu concentrations and isotope compositions in all the soil horizons, clearly contrasting with the isotopically lighter compositions of the carbonate bedrocks. Positive δ 65 Cu values in the tailing material affect the surface of the soil, especially soil sampled in its vicinity. In most Luvisols and Chernozems, the isotope composition of Pb exhibits similar patterns with a low 206 Pb/ 207 Pb ratio on the surface of the profile and with a slight increase to depth. The low 206 Pb/ 207 Pb values at the surface of the profiles are caused by dust from the tailings. The elemental and isotopic patterns of both contaminated and uncontaminated soil types reflect not only the distance from the tailing dam but also pedogenetic processes in the profiles and geochemical behaviour of both contaminants. The copper elemental and isotope patterns reflect the formation of more mobile species in the surface environment and movement of solutions and colloids and precipitation onto secondary minerals in Luvisols.

Environmental Pollution, Aug 1, 2018

Journal of Environmental Management, Feb 1, 2017

The leaching behaviors of primary copper (Cu) slags originating from Ausmelt, reverbatory, and co... more The leaching behaviors of primary copper (Cu) slags originating from Ausmelt, reverbatory, and converter furnaces operating under a single technological process were compared to a residual slag tailing obtained by slag reprocessing via flotation and metal recovery. The EN 12457-2 leaching test, used for assessment of the hazardous properties, was followed by the CEN/TS 14997 pH-static leaching test (pH range 3e12). Both leaching experiments were coupled with a mineralogical investigation of the primary and secondary phases as well as geochemical modeling. Metals (Cd, Cu, Pb, Zn) exhibit the highest leaching at low pH. Under acidic conditions (pH 3e6), Ausmelt slag and slag tailing exhibited higher metal leaching compared to other slag types. Very low leaching of metals (far below EU limits for nonhazardous waste) was observed at natural pH (7.9e9.0) for all the studied slag samples. In contrast, relatively high leaching of As was observed over the entire pH range, especially for Ausmelt slag (exceeding the EU limit for hazardous waste by 1.7Â). However, geochemical modeling and scanning electron microscopy indicated that formation of stable Ca-Cu-Pb arsenates and the binding of As to newly formed Fe (oxyhydr)oxides play an important role in efficient As immobilization at the slag-water interface. In contrast, no controls were predicted for Sb, whose leaching was almost pH-independent. Nevertheless Sb leached concentrations at natural pH were below EU limit for hazardous waste. Reprocessing of primary Cu slags for metal recovery, and subsequent co-disposal of the resulting slag tailing with dolomite-rich mine tailing and local laterite is suitable for stabilizing the remaining contaminants (except Sb) and limiting their leaching into the environment.

Physics And Chemistry Of The Earth, Parts A/b/c, Aug 1, 2019

Promoting evidence-based implementation of SADC water programmes and projects through multi-and i... more Promoting evidence-based implementation of SADC water programmes and projects through multi-and inter-disciplinary research, and synthesis of existing and new information, which will lead to a realisation of SADC developmental goals. Background Sub-Themes Development and Sustainable Implementation of Resilient Water Infrastructure Water for Health, Livelihoods and Economic Development Policymakers, academics, practitioners from water and related sectors, and cooperating partners are invited to register and attend the symposium and make use of this opportunity to listen and debate findings from presentations focused on the different sub-themes. Authors with accepted abstracts should now submit their full papers targeting the sub-themes below. Infrastructure that supplies water for multiple uses, and delivers adequate sanitation should be robust and resilient if it is to continue to provide vital services in a changing biophysical and socioeconomic environment.

Chemosphere, May 1, 2020

h i g h l i g h t s g r a p h i c a l a b s t r a c t Wildfires can affect smelter-impacted soils... more h i g h l i g h t s g r a p h i c a l a b s t r a c t Wildfires can affect smelter-impacted soils and vegetation in semi-arid Namibia. Mercury released from contaminated biomass-rich topsoils at~340 C. Smelter surroundings (184 km 2) contain~300 kg of Hg remobilizable by wildfire.

Journal of Environmental Management, Sep 1, 2021

The surroundings of mines and smelters may be exposed to wildfires, especially in semi-arid areas... more The surroundings of mines and smelters may be exposed to wildfires, especially in semi-arid areas. The temperature-dependent releases of metal(loid)s (As, Cd, Cu, Pb, Zn) from biomass-rich savanna soils collected near a Cu smelter in Namibia have been studied under simulated wildfire conditions. Laboratory single-step combustion experiments (250-850 °C) and experiments with a continuous temperature increase (25-750 °C) were coupled with mineralogical investigations of the soils, ashes, and aerosols. Metals (Cd, Cu, Pb, Zn) were released at >550-600 °C, mostly at the highest temperatures, where complex aerosol particles, predominantly composed of slag-like aggregates, formed. In contrast, As exhibited several emission peaks at ~275 °C, ~370-410 °C, and ~580 °C, reflecting its complex speciation in the solid phase and indicating its remobilization, even during wildfires with moderate soil heating. At <500 °C, As was successively released via the transformation of As-bearing hydrous ferric oxides, arsenolite (As2O3) grains attached to the organic matter fragments, metal arsenates, and/or As-bearing apatite, followed by the thermal decomposition of enargite (Cu3AsS4) at >500 °C. The results indicate that the active and abandoned mining and smelting sites, especially those highly enriched in As, should be protected against wildfires, which can be responsible for substantial As re-emissions.

Chemical Geology, Aug 1, 2018

The Tsumeb mining District (Namibia) is affected by prolonged exposure to multisource contaminati... more The Tsumeb mining District (Namibia) is affected by prolonged exposure to multisource contamination related to the mining and smelting of copper ores. This study was performed to assess the extent of contamination of topsoil and grass shoots on the basis of the copper isotopic composition. Compared to an uncontaminated area (δ 65 Cu soil =-0.01 to +0.14 ‰; δ 65 Cu grass =-0.17 to +0.03 ‰), the soil and grass in the contaminated area are enriched in the heavy isotope (δ 65 Cu soil = +0.13 to +0.76 ‰ and δ 65 Cu grass = +0.15 to +0.64 ‰). The Δ 65 Cu grass-soil value exhibits small variations (+0.06 to-0.17) due to the variable degree of grass surface contamination, depending on the grass washing procedure used. The enrichment of soil and grass in the contaminated area in 65 Cu reflects the Cu isotopic composition of old flotation tailings (δ 65 Cu =+0.95 to +1.1 ‰), slag (+0.11 to +0.55 ‰) and particles which originate from the smelting and flue gas cleaning processes (+0.15 to +0.49 ‰). The long history of mining and processing of copper ores in the Tsumeb area and the different isotopic composition of ore concentrates smelted in the local metallurgical plant do not allow assessment of whether the smelting process leads to isotope fractionation of copper. However, the isotopic composition of Cu in the sulfidic feed, slag and dust particles sampled over several hours showed that the dust collected from the dusthouse of the local smelter is isotopically lighter (δ 65 Cu = + 0.15 ‰) relative to the isotopic composition of the charge (δ 65 Cu = +0.28 and +0.44 ‰). The results of this investigation demonstrate that the isotopic composition of Cu in soils and grasses can be used to assess the intensity of contamination in areas where Cu ores are mined and processed provided that the isotopic compositions of the ore processing products are different from the isotopic compositions of the uncontaminated soils and vegetation.

Environment International, Mar 1, 2019

&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;Wildfires contribute to global emissions of trace elements. This study focuses on highly polluted areas near an operating copper smelter and old mine-tailing disposal sites in Tsumeb (semi-arid north of Namibia), where wildfires frequently occur. Capturing of particulates windblown from the ore processing and smelting areas by vegetation (trees, grass) leads to the topsoil enrichment with metal(loid) contaminants (up to 7090 mg/kg Cu, 2070 mg/kg As, 4820 mg/kg Pb, 3480 mg/kg Zn, 75 mg/kg Cd, 7.66 mg/kg Hg). Experimental samples corresponding to representative biomass-rich topsoils (bushland with acacia and marula trees, grassland) were investigated using a combination of mineralogical and geochemical methods. Wildfires were simulated using a thermodesorption (TD) technique (75-670 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C; Hg) and an experimental setup composed of a temperature-controlled furnace (250-850 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C), an aerosol-filtering unit and a gas-trapping device (As, Cd, Cu, Pb, Zn). The obtained ashes were investigated to depict any mineralogical and chemical transformations in order to understand temperature-dependent release of metal(loid) contaminants during the simulated wildfire.&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;Thermodesorption experiments indicated that more than 90% of Hg was released at ~340 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C, which corresponded to predominant grassland-fire conditions. A comparison with the TD curves of the Hg reference compounds confirmed that the Hg in the biomass-rich topsoils occurs as a mixture of Hg bound to the organic matter and metacinnabar (black HgS), which exhibited similarities with the TD pattern of smelter flue dust residue. Temperature-dependent release of other metal(loid)s (As, Cd, Cu, Pb, Zn) is dependent on their solid-state speciation. Cadmium is released at ~750 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C, corresponding to the thermal decomposition of carbonates, in which Cd is mainly bound. Arsenic exhibits first remobilization step at &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;350 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C (decomposition of arsenolite, As&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;2&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;O&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;3&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/sub&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;) and the second step at &amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;650 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C corresponding to the instability of arsenates and As-rich slag glass. Other contaminants (Cu, Pb, Zn) were mainly bound in carbonates, slag particles and sulfides/sulfosalts. During the simulated wildfire, they were mainly retained in the ash and were remobilized to a lesser degree at &amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;650 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C. Calculations indicated that at 850 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#176;C (worse-case wildfire scenario) 2-17 % of total As, Cu, Pb and Zn, 27-79 % of total Cd and 100 % of Hg can be volatilized from these biomass-rich contaminated topsoils.&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;This study was supported by the Czech Science Foundation (GACR project no. 19-18513S) and a student grant from the Grant Agency of Charles University (GAUK no. 1598218).&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;

Economic geology and the bulletin of the Society of Economic Geologists, May 1, 1994

... BENJAMIN SE MAPANI AND CHRISTOPHER JL WILSON School of Earth Sciences, University of Melbourn... more ... BENJAMIN SE MAPANI AND CHRISTOPHER JL WILSON School of Earth Sciences, University of Melbourne, Parkville, Victoria 3052, Australia ... Wilson et al., 1992); they are the oldest rocks exposed in a struc-ture referred to as the "Magdala anticline" (Wat-chorn and Wilson ...

South African Journal of Geology, Jun 1, 2023

The Koras Group is a bimodal volcanosedimentary group located in post-tectonic grabens in a forel... more The Koras Group is a bimodal volcanosedimentary group located in post-tectonic grabens in a foreland thrust complex in the Kaaien Terrane of the Mesoproterozoic Namaqua-Natal Province of southern Africa. It contains two sequences of mafic and felsic volcanic rocks with an unconformity between them, only the lower sequence being slightly folded. The Koras Group was long regarded as having formed at the end of the 1 210 to 1 000 Ma Namaqua Orogeny, because it lacks the severe deformation and metamorphism of the underlying rocks, with igneous minerals preserved in many samples. Following years of unsuccessful attempts to precisely date the volcanic rocks, the first two ion probe U-Pb zircon studies both reported ages of ~1 172 Ma for the Swartkopsleegte Formation felsic lava in the slightly folded lower sequence (based on relatively few dated zircons) and ~1 100 Ma for the Leeuwdraai Formation rhyolite in the undeformed upper sequence. Thus a major 70 m.y. hiatus seemed apparent between the lower and upper sequences despite their similar geochemistry and rift-related setting. This gave rise to models which envisaged the Kaaien Terrane being unaffected by the syn- to late-tectonic deformation, migmatisation and granite intrusions, documented between 1 200 and 1 150 Ma in the adjoining Namaqua-Natal terranes to the west. A high-pressure (10 kbar) metamorphic event, recognised in the Kaaien Terrane basement just south of hardly-deformed Koras Group exposures and dated at 1 150 Ma, is inconsistent with such models. A re-investigation and microbeam dating campaign on the Koras Group confirms the 1 101 ± 2 Ma (n = 6) age for felsic volcanic rocks of the upper sequence, but establishes a new reliable age of 1 114 ± 4 Ma for the lower one (n = 2). The 1 170 ages obtained in the earlier two studies were revisited and are now considered to reflect the age of zircon xenocrysts from the source rocks, which dominate the zircon population of some Swartkopsleegte Formation samples. Several criteria to distinguish autocrystic (magmatic) from antecrystic (age-overlappping xenocrystic) data points were investigated. One sample had high Th levels in only the younger zircons, but histograms of sufficiently precise 207Pb/206Pb ages provided the main criterion. Calculations of zircon crystallisation temperature intervals were not useful in predicting the abundance or proportions of magmatic and antecryst zircons. A multi-episode model of magmatic generation and crystallisation events is probably appropriate. In cases when felsic volcanic samples yield few zircons, care must be taken to avoid the problem exposed in this study. The Koras Group sediments have similar detrital zircon U/Pb age distributions to those of the Rehoboth Basement Inlier. This supports the concept that the Kaaien Terrane originated as the southern part of the Rehoboth Province.