Distribution of heavy minerals sand in Namalope deposit, Moma district, Mozambique
- Authors: Assane, Ali Ossufo
- Date: 2014
- Subjects: Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5056 , http://hdl.handle.net/10962/d1012169 , Heavy minerals -- Mozambique -- Moma District , Prospecting -- Mozambique -- Moma District , Mines and mineral resources -- Mozambique -- Moma District , Ilmenite -- Research , Zircon -- Research , Rutile -- Research
- Description: The spatial distribution of heavy minerals along the mine paths 2014 and 2015 at the wet concentrate plant B shows an increase of heavy minerals sand concentration northwards and slime contents southwards, and it is commonly associated with depth and grain sorting; the increase of heavy minerals concentration with depth is considered to be from the surface formed by Unit 6 to the bottom of Unit 7. The Unit 82 is characterized by low heavy minerals concentrations and high slime contents declining northwards. The mineral proportion estimation suggests that ilmenite is the most abundant heavy mineral in the entire area followed by zircon, rutile and mozanite, and some accessory minerals such as chromite, kyanite, staurolite, tourmaline, epidote, spinel and quartz. The ilmenite occurrence is divided into ilmenite low (< 53% TiO₂) and high (> 53% TiO₂); the ilmenite high with zircon and rutile shows tendency to increase northwards while ilmenite low increase southwards. Zircon, monazite, rutile, chromite, kyanite and staurolite show low variability, which is probably associated with high resistance of minerals for abrasion during transportation and diagenesis. The depositional model of the Namalope deposit, in the flat area and wet concentrate plant B in particular, suggests deposition in a shallow marine environment associated with regression for deposition of Unit 6, 7 and 9 and transgression during deposition of Unit 82. The spatial distribution of heavy minerals in the Namalope deposit and its environment of deposition are the key points for discovery of new deposits around the Namalope with the same characteristic of mineral assemblage and they are used for mine strategic plans such as update block model and mine design.
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- Date Issued: 2014
Gold mineralization in a high grade metamorphic terrane in the Handeni District, Eastern Tanzania
- Authors: Bitesigirwe, Godfrey Stephen
- Date: 2014
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54756 , vital:26609
- Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
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- Date Issued: 2014
Petrological, mineralogical and geochemical studies of Zhongchang and Yantiangou ultramafic intrusions from the Panxi region, Sichuan Province, S-W China. Metallogenic and Exploration implications
- Authors: Malatji, Tsholofelo S
- Date: 2014
- Subjects: Mineralogy -- China , Geochemistry -- China
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5057 , http://hdl.handle.net/10962/d1012951
- Description: The Emeishan Large Igneous Province is one of the largest igneous provinces in the world. It is marked by basaltic extrusives that vary in Ti amount, classified as high Ti and low Ti. Several mafic to ultramafic intrusions occur in the province as well as granitic intrusions. The mafic-ultramafic intrusions are associated with mineralization; large layered utlramafic intrusions bearing Fe-Ti-V mineralization, while small dyke like or sill like intrusions contain Cu-Ni-PGE mineralization. The Zhongchang and Yantiangou mafic- ultramafic intrusions are small such intrusions bearing Ni-Cu-PGE mineralization. The deposits show a lot of similarities in source magma, evolution and mineralization. Parental magma for both deposits show alkaline tendencies, and a high Mg # indicative of primitive magma that underwent little crustal contamination. Mantle range Cu/Pd ratios show parental magma fertile in chalcophile elements and both deposits proceed to show depleted mantle normalized values as a result of sulphide saturation and subsequent mineralization. Mineralization in Zhongchang is hosted at the contact between peridotite and pyroxenite, interstitial to olivine and clinopyroxene. Alteration minerals include epidote and chlorite. High Cu/Pd ratios suggest earlier sulphide saturation and removal of a PGE sulphide, and a second sulphide saturation phase resulted in Ni-Cu mineralization. Mineralization in Yantiangou is hosted in biotite effectively following fractionation of olivine and clinopyroxene after which sulphide saturation occurred, precipitating sulphide minerals in biotite. Pyrite and millerite occur as a result of late stage hydrothermal alteration. Cu/Pd ratios are high indicating prior sulphide saturation occurred where PGE partitioned into sulphides. Ni/MgO ratios observed for both deposits indicate a state of sulphide under saturation where PGE partitioned into tellurides and bismurthinides and Ni into olivine. Average tenors for mineralized units are; Zhongchang at 5%Ni, 9% Cu, 4300ppb Pt and 2000ppb Pd, and Yantiangou having relatively lower tenors at 3.2%Ni, 6.5% Cu, 3000ppb Pt and 1300 ppb Pd.
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- Date Issued: 2014