Electronic Theses and Dissertations (Masters)

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An investigation into high gear and low gear propulsion in human gait and its relation to metatarsal diaphyseal geometric cross-sectional properties
(University of the Witwatersrand, Johannesburg, 2023-06) Reyneker, Mark Brenden; Carlson, Kristian J.; Zipfel, Bernhard
This study investigates the relationship between metatarsal bone form, as quantified by cross-sectional geometric properties, and its relationship to high (medial forefoot loading) versus low gear (lateral forefoot loading) push-off during the propulsion phase of the gait cycle. The objective being to assess whether forefoot loading may be variable or whether high gear loading occurs in higher frequencies, as depicted in theoretical foot function models. The study sample (n=53), made up of three broad groups, include Later Stone Age southern Africans, post-industrial individuals from South Africa, and the Jomon of Japan. Metatarsals 1-5 cross-sectional geometric properties (CSA, Ix, Iy, Imin, Imax, Zx, Zy, Zp, Zmin, Zmax) taken from CT scans at 25%, 35%, 50% and 65% metatarsal diaphyseal biomechanical lengths are grouped into high gear (metatarsal 1-2) and low gear (metatarsal 2-5) for comparison. The combined population analysis reveals that the high gear metatarsal diaphysis exhibit significantly higher strength and rigidity driven mainly by the post-industrial individuals from South Africa and the Later Stone Age southern Africans. In contrast, the Jomon of Japan, exhibit no significant differences between high and low gear metatarsals except for CSA, Imax, and Zmax. Furthermore, metatarsal 1 and 5 differ far less in cross-sectional geometric properties in the Jomon of Japan compared to the other populations except for medial-lateral strength (Zy) and torsional and average bending strength (Zp) where metatarsal 5 is significantly higher. The study findings indicate that forefoot loading demonstrates variability during the propulsion phase of gait, while also suggesting a higher frequency of occurrence for high gear push-off. This challenges current theoretical models of foot function that emphasise high gear push-off as typical and normal for striding bipedalism.
Cranial orientation and the lateral semicircular canal in primates: implications for palaeobiological reconstructions and the evolution of locomotor repertoires
(University of the Witwatersrand, Johannesburg, 2023) Pestana, Christopher; Benoit, Julien; Beaudet, Amélie
The lateral semicircular canal and its predicted relation to head posture have been used in reconstructions of locomotion and posture of contemporary and extinct species, and in the evolution of bipedalism. Inferences of head posture in fossil species sometimes assume that the lateral semicircular canal is held near the earth’s horizontal when the head is at rest. Despite the physiological importance of the vestibular system, the relationship between head posture and lateral semicircular canal orientation in primates has not been explored on a statistically significant sample, using phylogenetically corrected methods. This study tests the hypothesised relationship between lateral semicircular canal orientation and head posture in primates, and investigates potential links to locomotor categories. This study finds that lateral canal orientation is not significantly correlated to positional repertoires. Significant differences in canal orientation are detected between terrestrial and arboreal species. Neutral head posture distinguishes several locomotor categories, and explains a moderate proportion of the variance in positional behaviour. Brain mass is found to correlate with positional behaviour when correcting for the effects of the phylogeny. The implications of the evolution of head posture in fossil species are discussed.
Exploration Geology of Structurally Controlled Sediment-Hosted Gold Mineralization at Kasenseli, Northwestern Zambia
(University of the Witwatersrand, Johannesburg, 2023-10) Mulenga, Kapalakasha; Kinnaird, Judith; Nex, Paul
Occurrences of economic quantities of gold within the Roan and Nguba groups of the Katanga sedimentary units are not a common phenomenon. This is a new area of exploration for gold, and very little exploration work has been done to act as a guide in such a geological environment. More common are post-Nguba unit or Kundelungu group related gold occurrences which respectively occur around the Kasempa and Mumbwa areas and these are related to the Hook granite as well as the major shear zones that traverse these areas. The study area lies within the Lufilian Arc Fold and Thrust Belt and is located on the western end of the external fold and thrust zone which is part of the western extension of the Zambian Copperbelt. The area covering Mwinilunga is subdivided into four terranes based on regional structural features and metamorphism. The four terranes are; the Kasai Shield, the Kabompo Dome, the Western Foreland and the Lufilian Arc. Four main units that are present within the study area include the Roan member shale unit, the arkosic sandstone and its related sub-units which occur as lenses within this main unit, the Grand Conglomerat marker unit (diamitite), and the Nguba member shale which is interbedded with siltstone in some zones. Based on the contact relationship of the units to Grand Conglomerat marker unit, the oldest unit within the study area is the Roan shale unit (which could be of Mwashya age or older), followed by the arkosic sandstone, the diamictite unit which is the Grand Conglomérat marker unit and finally the Nguba shale. Polished thin section and mineral liberation analysis was undertaken on most of these units. Among the notable features of the stratigraphy in the area is the presence of a redox boundary between the pinkish-grey coarser arkosic sandstone unit (oxidising facies) and the greenish-grey clast-poor diamictite (reducing facies) where richer pockets of gold mineralisation have been observed. Gold mineralisation has been mainly observed to be hosted in the clast-poor diamictite mostly in the alteration halo which forms around the arkosic sandstone-quartz vein-diamictite contact. Further away from this contact and away from other related structures such as faults, veins and folds, mineralisation gradually diminishes. Gold mineralisation in this area shows a strong correlation to copper with the high- grade zones having elevated copper mineralisation both in the mineralised zone and in the residual soils. On a district scale, the study area and its surroundings are extensively folded and faulted, and the area has undergone episodic deformation resulting in the development of various structures. Among the notable structures within the study which are relatable to the Lufilian Arc Fold and Thrust Belt (LAFTB) on district to regional scale include folding, shear faulting, normal faulting, and the development of joints. The structural aspect plays a critical role with regards to the location of mineralisation. Observed structural features which were critical as pathways and deposition site of uriferous/mineralised fluids include first order folding with a NNE – SW oriented axial trace as well as first order NE – SW oriented shear faults and shear zone, the second order NW – SE oriented faults and veins which are the structures that host the mineralisation, and the NW – SE oriented (axial trace) folding where saddle-reef hosted mineralisation has been observed within the study. The physiochemical redox boundary between the Nguba member diamictite (reducing facies) and pre-Nguba arkosic sandstone (oxidised facies) played a critical role in the location of the mineralisation in the area. One thousand six-hundred and fifty (1650) soil samples were collected from the entire study area which covers a surface area of about 13 square km. Analysis and interpretation of soil assays showed that only copper may reliably be used as pathfinder in the exploration for gold mineralisation and/or deposits particularly in Nguba group member units. In addition, based on stratigraphic correlation, the possibility of Kamoa-style copper mineralisation has been suggested.
Hydrogeological assessments and investigation of inflow sources at Lumwana Copper Mine, Zambia
(University of the Witwatersrand, Johannesburg, 2023) Mbilima, Mike; Abiye, Tamiru
This Research Report presents results of integrated field and desktop-based hydrogeological investigations at the Lumwana Mine, Zambia. Groundwater occurrence in the mine poses challenges with effective mining operations and slope stability. The primary aim of this study was to establish the sources of groundwater inflows and to establish the nature of surface water and groundwater interaction within the Lumwana Mine hydro-geotechnical units. The Lumwana hydrogeological investigation has been achieved through the integration of multi-disciplinary data types, which include geology, structures, hydrochemistry, meteorological data (rainfall, temperature, humidity and evapotranspiration), environmental isotopes, dewatering pumping records, groundwater level monitoring, water temperature, general hydrogeological data and surface hydrology. The investigation has confirmed the presence of hydraulic connections between different surface water bodies such as dams, diversion channels, streams and open pit excavation, and has proven to be a useful approach in tracing the source of mine inflows. Rainfall, groundwater and surface water samples have similar δ18O and δ2H isotopic signatures thus lamenting the existence of a hydraulic link between groundwater and surface water. Recharge estimation through Water Table Fluctuation method (WTF) determined 8% of mean annual precipitation (MAP). The dominant hydrochemical facies are Ca-Mg-HCO3 and Ca-Mg-SO4. The local geology and geochemistry of the tailings are the main controllers of groundwater chemistry through rock-water interaction. The geology of the study area consists of older metamorphosed gneisses, schists, migmatites, amphibolites and granitoids. Integrated assessment of the Lumwana hydrogeological environment has enabled the development of the Lumwana Mine hydrogeological conceptual model. In the shallow, highly to moderately weathered zones, groundwater flows from south towards low topographic regions in the northwest mimicking the general topography. The hydraulic test conducted at Lumwana Mine has revealed the saprock units have higher hydraulic conductivity by several orders compared to the saprolites and the fresh bedrock, where groundwater flow is mainly controlled by the occurrence and distribution of the fracture network.
Near-surface geophysical investigation of the Far Western Limb of the Bushveld Complex, South Africa
(University of the Witwatersrand, Johannesburg, 2023-10) Nadan, Thiashen; Scheiber-Enslin, Stephanie; Manzi, Musa
Platinum Group Elements (PGE’s) and chromium are the main economic minerals that are found within the Bushveld Complex. In particular, the Far Western Limb of the Bushveld Complex has not been completely explored, as it is overlain by a thick Quaternary sedimentary deposit which masks the contacts between the different underlying lithological units. Chromium outcrops within the Far Western Limb have already been identified and mined. The study aims to assess the feasibility of extended geophysical surveys which will further identify the shallow subsurface lithologies and evaluate the future mining potential in the area. Results of this study show that the quaternary cover is approximately eighty meters thick, implying a shallow bedrock within the Far Western Limb. This was used to delineate a contact between the Transvaal Supergroup and the Rustenburg Layered Suite that was lost beneath the sedimentary cover. This shows that shallow geophysical investigations and drilling can prove useful in delineating the lithologies hosting the chromium ores.
Potential Source for the Alluvial Gold Deposit in the Kapoeta Area, Eastern Equatoria State, South Sudan
(University of the Witwatersrand, Johannesburg, 2023-10) Bali, Francis Khamis Alex; Woldai, Tsehaie; Kinnaird, Judith A.
This study concentrates on the integrated approach of applying geochemical, and remote sensing data combined with field investigation to understand the source of the alluvial gold deposit in the Kapoeta area. The use of an integrated technique approach proves effective in mapping and outlining areas of potential gold mineralisation in Kapoeta. Kapoeta has been known for its endowment of gold deposits for quite some time. Landsat-8 (OLI) and SRTM-DEM satellite images were employed during this study to map lithological units and highlight areas of hydrothermal alteration and structural trends in Kapoeta to understand the potential source for the widely distributed alluvial gold in the area. The several image-processing techniques employed were effective in mapping the lithological units and outlining the major structural trends in the area. Mapping the hydrothermal alteration zones was challenging because of the overburden that masks most parts of the Neoproterozoic juvenile metavolcano-sedimentary sequences. Secondly, the vegetation cover is another factor affecting the mapping of the lithological units around the Didinga Hills and Dongotona mountains. Structural mapping identified four main trends N-S, NNW-SSE, NW-SE, and NE-SW. The image interpretation, together with geochemical occurrence and anomaly map showing Cu, Co, Ni, and Cr, shows that N-S and NNW-SSE are the potential controls on mineralisation in the area. The whole-rock geochemical data plotted on the TAS discrimination diagrams shows that the rocks analysed are dominantly tholeiitic with minor calc-alkaline units. Trace elements normalised to the primitive mantle show low concentrations of Zr, Hf, Nb and Ta. The REE normalised chondrite values indicates general enrichment of LREE elements relative to HREE with a negative Eu anomaly. On the tectonic discrimination diagrams, the results indicate that the rocks of Greater Kapoeta belong in a marine environment related to a spreading centre, oceanic island, oceanic ridges, and floor. The distribution of Cu, Co, Cr and Ni and their high concentration suggest that these elements are the potential pathfinders for gold in the area. The study concludes the following: Based on the remote sensing, field observations and geochemical data indicates that the gold mineralisation of Kapoeta is orogenic in nature with a strong element of epigenetic characteristics, however, a syngenetic origin cannot be ruled out. The host lithologies may vary from quartz veins to schists, amphibolites, quartzo-feldspathic gneisses, and ultramafics and the marbles related to the N-S, NNS-W-SSE and NW-SE trending shear zones that limit the greenstone belt.
Reconstructing locomotor behaviour of Southern African plio-pleistocene cercopithecoids: evidence from functionally-related inner structural arrangement of the trabecular bone
(University of the Witwatersrand, Johannesburg, 2023-07) Babutsi, Mosarwa; Beaudet, Amélie; Zipfel, Bernhard; Jakata, Kudakwashe
Because of their abundance in African Plio-Pleistocene hominin-bearing sites and their stratigraphic association with fossil hominins, cercopithecoids represent a relevant “control group” for contextualising hominin evolution. often considered as ecological and biochronological indicators, particularly their ecological sensitivity is valuable in reconstructing southern African hominin bearing site’s palaeoenvironment and environmental changes. Since biomechanical loadings on trabecular bone produced throughout locomotor activities shape the structure of the skeleton, particularly at locomotor key joints, the expectation is that investigation of the trabecular bone of fossil cercopithecoids key joints like femur, humerus, Tibia and calcaneus would provide further evidence for eloquent discreet disparity in their locomotor behaviour and reconstructing their paleohabitats. This study used trabecular bone, described as meshwork or sponge with porous network within long bones joints and inside footbones contains red bone marrow. Its preferred orientation in is the basis of Wolff’s law, relating bone structures and its ability to adapt to mechanical load alignment in the direction of loading stress, as such recoding informative locomotor signals. Forty one (41) fossil cercopithecids from the Cradle of Humankind World Heritage sites that include Sterkfontein, Swartkrans, Makapansgat, Taung and Bolt’s Farm as well as forty (40) extant cercopithecoids specimens were scanned using a micro-focus X-ray computed tomography (CT) scanner. Trabecular bone parameters that include trabecular bone fabric anisotropy, volume fraction, thickness and spacing were quantified in ImageJ. These Plio-Pleistocene cercopithecoids recorded more arboreal locomotor signals with occasional terrestrial locomotion, suggesting transitional palaeoenvironment from long trees with cool climatic conditions to a more open grass land savanna type with dry climatic conditions believed contributed significantly to extinct of archaic humans and the emergence of the successful Homo.
Sedimentology and geochronology of the fossil bearing upper member of Malapa site in the Cradle of Humankind (South Africa, Johannesburg)
(University of the Witwatersrand, Johannesburg, 2023-08) Maphanda, Dakalo Portia; de la Peña, Paloma; Jinnah, Zubair; Makhubela, Vincent
Malapa is a palaeoanthropological site in the Cradle of Humankind in South Africa. It is known for preserving two partial skeletons of Australopithecus sediba. These skeletons are encased in Pleistocene cave deposits that are subdivided into six sedimentary facies i.e., A-F. There are two pits exposed at the site i.e., the main pit (pit 1) and pit 2. Sedimentary facies A-E are deposits from the main pit, and facies F occurs in both pit 1 and 2. Pit 2 deposits were previously classified as a homogenous deposit of facies F. Recent excavation campaigns carried out in 2019 and 2020 exposed new deposits adjacent to the deposits in pit 2. The purpose of this study was to enhance the geological understanding of the deposits at Malapa by investigating the newly exposed deposits. We found that facies F deposits are not as homogenous as previously thought, based on grain size, textural variation, and general appearance of the deposit. The newly exposed deposits and facies F were collectively called the upper member as they entail the deposits investigated in this study. Facies F and the newly exposed deposits were then targeted for sampling to investigate the petrography of the deposits. The study also investigated the stratigraphic position of the upper member in relation to facies A-F from the main pit by attempting to resolve an age of the deposits. The study utilized a sedimentary analysis approach by combining petrographic descriptions, mainly SEM-EDS and XRF to confirm the existence of multiple facies in the upper member. The results show that the upper member comprises facies B, C, F and a newly defined facies G. Facies G contains more chert and quartz clasts than any facies described in the previous studies. It only has calcite in the form of a micrite matrix supporting chert, quartz, or Mn-Fe-coated grains. Considering that the six facies from previous studies are chronologically well constrained, the age of facies G was also investigated. Two flowstones were used to estimate the maximum age of the clastic sediments. Flowstone 2 was situated between the clastic sediments of facies B, C and F so it represents a maximum age for sediments below it and the minimum age for those above it. Flowstone 2 is the same as the Flowstone 2 sampled by a previous study where it returned a well-constrained age of 2.06 ± 0.021 Ma. Flowstone 3 was determined to be a clast that could have collapsed from the cave roof and was situated in previously unstudied sediments. The sediments were determined to be Facies C deposits close to Pit 1. We attempted to date Flowstone 2 by U-Pb LA-ICP-MS but attained an age of 3.72 ± 0.77 Ma (Pliocene in age), inconsistent with previous dating and unrealistic in the context of the Malapa. Flowstone 3 produced a U-Pb age of 7.50 ± 0.37 Ma (Miocene in age). The U-Pb flowstone ages have large errors. Flowstone 2 has an error of ~21% of the age and flowstone 3 has an error of ~5%. Both flowstone ages have too large an error to be considered useful to constrain the age of the upper member. A second dating approach was then used on the clastic sediments themselves using cosmogenic nuclide burial dating. The method yielded more well-constrained ages of 1.59 ± 0.44 Ma. This is an isochron burial age that suggests that the upper member is much younger than the deposits in the main pit, but the isochron burial age is in agreement with the literature U-Pb ages from the flowstones. This is because 1.59 + 0.44 = 2.03 Ma which coincide with the U-Pb ages of the flowstones in the main pit and pit 2. The age of the samples from facies G have an average age of 1.52 ± 0.088 Ma which makes facies G the youngest in stratigraphy.
The relationship between dental complexity and mandibular shape: implications for dietary inference in stem mammals
(University of the Witwatersrand, Johannesburg, 2024) Harris, Wade; Choiniere, Jonah N.
Non-mammalian cynodonts exhibit some of the first major morphological innovations that contributed to the success of their descendent lineage, mammals. This includes features that are hypothesized to enable adaptation to a highly varied suite of diets such as specialized tooth crowns with complex occlusal surfaces and a jaw muscle configuration where two major muscles contribute to jaw closing. Surprisingly, inferences on cynodont diets so far have been based on qualitative evidence, and the quantification of these dietary adaptations could assist in testing these inferences. Here, I evaluate the relationships of mandibular shape, dental complexity and the combined data on body mass and relative mandible size, to known diets in living mammals, to assess the utility of these ecomorphological proxies for inferring the diets of extinct non-mammalian cynodonts. To assess relationships between diet and jaw shape, I collected 12 fixed landmarks (type 2) and four sliding landmarks (type 3) for six non- mammalian cynodonts, 51 marsupial mammals and 211 placental mammals. Dental complexity (OPCR) values were collected using the R package molaR, for a sample of 19 non-mammalian cynodonts, 47 marsupial mammals and 193 placental mammals. Procrustes-aligned shape coordinates, OPCR values, body mass estimates and relative mandible size data were then subjected to phylogenetic Procrustes ANOVA regressions and phylogenetic regressions. Neither mandible shape nor OPCR are strongly correlated to diet (carnivory, frugivory, granivory, herbivory, nectivory, invertivory), but the combination of these variables are a somewhat reliable predictor of diet, particularly mandible shape. Extinct non-mammalian cynodonts have mandible shapes that are comparable to those of mammals, however they occupy a narrow morphospace and their OPCR scores are generally much lower than those of mammals. Consequently, when these variables were entered into a predictive framework for diet, I observed limited inferential power since non-mammalian cynodonts do not strongly resemble mammals.

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