MSUIR Collection:
https://cris.library.msu.ac.zw//handle/11408/4603
2024-03-29T12:54:06ZZimbabwe’s coloured gemstone endowments – A regional geological overview
https://cris.library.msu.ac.zw//handle/11408/5968
Title: Zimbabwe’s coloured gemstone endowments – A regional geological overview
Authors: A. Mamuse; B.P. von der Heyden; T. Blenkinsop
Abstract: Zimbabwe hosts a varied array of coloured gemstones. With the exception of emerald deposits
and several world-class pegmatites, few of the gemstone occurrences have received detailed
attention from the scientific or mineral exploration communities. In the present contribution
we summarize the status of knowledge of the gemstone deposits and occurrences in Zimbabwe,
paying particular attention to the geological settings in which they were formed. Synthesis of this
regional geological approach reveals that there may be significant exploration potential for further
gemstone occurrences, particularly in the extensive pegmatite fields and in Al-enriched orogenic
belts that have undergone greenschist to granulite facies metamorphism. Further socio-economic
and developmental initiatives will aid in optimizing the value generation from this important sub sector.2024-01-01T00:00:00ZA. MamuseB.P. von der HeydenT. BlenkinsopPetrographic and mineral chemistry investigation of the high-grade chrysotile asbestos-bearing Zvishavane Ultramafic Complex, south central Zimbabwe
https://cris.library.msu.ac.zw//handle/11408/5808
Title: Petrographic and mineral chemistry investigation of the high-grade chrysotile asbestos-bearing Zvishavane Ultramafic Complex, south central Zimbabwe
Authors: Antony Mamuse; Jeff B. Chaumba
Abstract: The Zvishavane Ultramafic Complex (ZUC) in the south central part of the Zimbabwe craton is comprised of coarse-grained serpentinites, metadunites and metagabbros and hosts Africa's largest reserves, and largest mine, of high-grade chrysotile asbestos. Magnesiohornblende, actinolite, plagioclase (An0.6–41.9), augite, diopside and clinozoisite constitute the mineralogy of the ZUC. Forsteritic olivine (>Fo90) was altered to form chrysotile and antigorite minerals, although some primary olivines are preserved. Contents of Al2O3 range from <1 to >2.5 wt% at TiO2 values of <0.7 wt% consistent with an island arc setting for the ZUC that originated from tholeiitic magmas. The Zvishavane Ultramafic Complex was metamorphosed at relatively high temperatures (542-779 °C) and low pressures (1.2-2kbars), consistent with contact metamorphism. Intrusion of several granitic batholiths relatively close to the ZUC likely triggered hydrothermal fluid migration which metamorphosed the ZUC. The associated asbestos deposits likely formed during hydrothermal circulation events. Zoned amphiboles, the occurrence of magnesiohornblende and actinolite, as well as cross-cutting serpentine veins are consistent with at least two stages of alteration and/or metamorphism of the ZUC. The lack of a thrust contact between the ZUC and its country rocks is consistent with the ZUC having intruded into the host Zvishavane Gneiss Complex and possibly acted as a feeder to the nearby Mberengwa greenstone belt (MGB). However, the occurrence of near end-member forsteritic olivine, the presence of zoned amphiboles, and faulting within the ZUC are all suggestive of an ophiolitic origin although forsteritic olivines also occur in intrusive layered complexes. Metamorphism of the ZUC, ascribed to intrusion of multiple batholiths and possibly the MGB, likely led to the formation of ZUC chrysotile asbestos deposits.2023-05-01T00:00:00ZAntony MamuseJeff B. ChaumbaThe Mutare-Fingeren Dyke Swarm: the enigma of the Kalahari Craton's exit from supercontinent Rodinia
https://cris.library.msu.ac.zw//handle/11408/5560
Title: The Mutare-Fingeren Dyke Swarm: the enigma of the Kalahari Craton's exit from supercontinent Rodinia
Authors: Antony Mamuse; Ashley P. Gumsley; Michiel de Kock; Richard Ernst; Anna Gumsley; Richard Hanson; Sandra Kamo; Michael Knoper; Marek Lewandowski; Bartłomiej Luks; Ulf Söderlund
Abstract: The Rodinia supercontinent broke apart during the Neoproterozoic. Rodinia breakup is associated with widespread intraplate magmatism on many cratons, including the ca. 720-719 Ma Franklin large igneous province (LIP) of Laurentia. Coeval magmatism has also been identified recently in Siberia and South China. This extensive magmatism terminates ⁓1 Myr before the onset of the Sturtian Snowball Earth. However, LIP-scale magmatism and global glaciation are likely related. U-Pb ID-TIMS baddeleyite dating herein identifies remnants of a new ca. 724-712 Ma LIP on the eastern Kalahari Craton in southern Africa and East Antarctica: the combined Mutare-Fingeren Dyke Swarm. This dyke swarm occurs in north-eastern Zimbabwe (Mutare Dyke Swarm) and western Dronning Maud Land (Fingeren Dyke Swarm). It has EMORB-like geochemistry, suggesting an asthenosphere mantle source for the LIP. The Mutare-Fingeren LIP likely formed during rifting. This rifting would have occurred almost ⁓100 Myrs earlier than previous estimates in eastern Kalahari. The placement of Kalahari against south-eastern Laurentia in Rodinia is also questioned. Proposed alternatives, invoking linking terranes between Kalahari and south-western Laurentia or close to north-western Laurentia, as alternative scenarios, also present challenges with no discernible resolution. Nevertheless, LIP-scale magmatism being responsible for the Sturtian Snowball Earth significantly increases.2023-02-10T00:00:00ZAntony MamuseAshley P. GumsleyMichiel de KockRichard ErnstAnna GumsleyRichard HansonSandra KamoMichael KnoperMarek LewandowskiBartłomiej LuksUlf SöderlundTextural characteristics, mode of transportation and depositional environment of the Stormberg Group in the Eastern Cape, South Africa: evidence from grain size and lithofacies analyses
https://cris.library.msu.ac.zw//handle/11408/5067
Title: Textural characteristics, mode of transportation and depositional environment of the Stormberg Group in the Eastern Cape, South Africa: evidence from grain size and lithofacies analyses
Authors: Chima, Priscilla; Baiyegunhi, Christopher
Abstract: The Stormberg Group comprises the Molteno, Elliot and Clarens formations and is one of four stratigraphical groups
that make up the Karoo Supergroup in South Africa. The group is the highest unit in the Karoo Basin, representing the
final phase of preserved sedimentation. The major problem with the Stromberg Group is that the mode of transport, hy-
drodynamic energy conditions and depositional environment are still poorly understood. For the present paper, grain
size and lithofacies studies on selected sandstones from the Molteno, Elliot and Clarens formations were performed
so as to elucidate their textural characteristics, depositional processes, sedimentation mechanisms and hydrodynamic
energy conditions and to discriminate different depositional environments. The statistical parameters of grain size
distribution (mean grain size, standard deviation, skewness and kurtosis) show that the sandstones are predominantly
unimodal, fine grained, moderately well sorted, mesokurtic and near symmetrical. The bivariate diagrams of the afore-
mentioned statistical parameters demonstrate that river and aeolian dune had the greatest impact on the depositional
environments. Likewise, the C-M pattern (Passega diagram) shows that the sandstones were mostly deposited through
tractive current process. Furthermore, the C-M diagram reveals the prevalence of rolling, suspension and graded sus-
pension modes of sediment transportation. Seventeen sedimentary lithofacies were identified and grouped into seven
lithofacies associations. These lithofacies associations indicate braided channel, overbank and swamp deposits for the
Molteno Formation, alluvial fan/floodplain and playa deposits for the Elliot Formation and aeolian deposits for the
Clarens Formation.2022-05-14T00:00:00ZChima, PriscillaBaiyegunhi, Christopher