Master Dissertations

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Mineralogy and geochemical characteristics of Matamba kaolin deposit-Njombe region - South Western Tanzania: implication for industrial applications
(The University of Dodoma, 2023) Nyimbo, Augustino M
Kaolin is commercial clay material composed of the hydrated aluminosilicate mineral kaolinite used in various industrial applications such as ceramics, paper, paints, refractories, fibreglass, plastics, cosmetics and pharmaceuticals. It is formed as a result of strong chemical weathering of crystalline acidic rocks such as granite, diorite, dacite or hydrothermal alteration of granitic rocks at relatively low temperature and pressure conditions. Matamba kaolin deposit is formed by kaolinization processes of leucogabbroic rocks that are characterized by high content of feldspars. In view of the highlighted properties, the mineralogy and chemical characteristics of Matamba kaolin deposit were investigated to determine its industrial applications. As part of the study approach, forty-six (46) samples were collected and analysed for major oxides using X-ray fluorescence (XRF) and mineralogical composition using X-ray diffraction (XRD) at Geological Survey of Tanzania laboratory and at the Department of Geosciences of the University of Dar es Salaam, respectively. The XRD results indicate that, Matamba kaolin deposit is dominantly composed of kaolinite (21.6–100%) with other minerals being albite (1.2-56.8%), oligoclase (10.1-54.3%), quartz (1.2-33.9%), goethite (1.0-9.4%) and muscovite (1.1–29.5%). The major oxides of the kaolin are dominated by SiO2 and Al2O3 in the range of SiO2 (39.78 - 67.96 wt.%), Al2O3 (14.60 - 38.07 wt.%) and subordinate amounts of Fe2O3 (0.93 - 6.37 wt.%), MgO (1.42-4.74 wt.%), Na2O (0.10–1.09 wt.%), K2O (0.14–2.01 wt.%), CaO (0.08-0.99 wt.%), TiO2 (0.07-1.66 wt.%), P2O5 (0.36-1.77 wt.%) and LOI (1.91–13.97 wt.%). These major oxides correlate with the mineralogical composition which supports the dominance of kaolinite mineral phases. Consequently, these results when compared with some industrial specifications indicate that, the Matamba kaolin deposit can be used for ceramic products, refractories such as fireclay crucible manufacturing and electrolytic production of aluminium and its alloys. However, this kaolin should be beneficiated and upgraded to improve some technical properties to qualify for other industrial applications.
Integrating geophysical signatures for delineating mineralized zones in Ikungi, Central Tanzania
(The University of Dodoma, 2023) Matiku, Raymond P.
This study presents the results of nine potential zones of mineralization in Ikungi, Manyoni Singida region. Integration of high-resolution geophysical signatures and geochemical data sampled from both active and abandoned pits have provided insights into the structural controls of mineralization and delineated the most potential mineralized zones in the study area. The geophysical signatures, which were obtained from magnetic, radiometric and VTEM datasets facilitated the understanding of structural controls such as faults and shear zones and identifying the most favourable location for gold mineralization. The results of the geophysical anomalies have delineated the subsurface structures, anomalous bodies, and lithological boundaries, which all play important control on gold mineralization. The geophysical anomaly results have delineated the presence of subsurface structures, which control the mineralization. These faults and shears structures are characterized by NW-SE, SW-NE and E-W trend direction. Furthermore, the geochemical laboratory analysis results have revealed high-gold concentrations from these structures, which supports the presence of significant mineral deposits in the area. Nine zones of mineralization are found in Granitic gneiss implying that the gneiss might have been affected by phases of metamorphism and deformations. The presence of active gold mines such as Shanta Gold Mine and Muhintili Artisanal Mine pits in the study area increases the likelihood of gold mineralization of the rest of the seven (7) potential zones in the study area.
Geological controls on gold mineralization in tumbelo area, kondoa district, Central Tanzania
(The University of Dodoma, 2023) Saidi, H.
The geological controls on gold mineralization in Tumbelo area were studied by utilizing a combination of the high-resolution airborne geophysical, geochemical and geological data. The airborne magnetic, radiometric and gravity data were gridded, filtered and enhanced for better resolution and displayed in different map formats to characterize lithological units and delineate geological structures. Laboratory fire assay, XRF and thin-section analyses were performed to find gold concentrations and their associated elements. The aeromagnetic and gravity data identified E-W, N-S, NNE and NNW as the prominent trends of major and minor lineaments which control gold mineralization. Bouguer gravity identified a large body of density greater than 30 mgals which correlates with magnetic low in the northeastern part and is interpreted as a deep-seated major intrusive, and analytic signal identified minor intrusives which might be associated with gold mineralization. The 3D Euler and Werner deconvolutions estimated depths beneath the surface for geological structures and intrusives to range from less than 22.6 m deep to more than 1500 m deep. Radioelement concentrations show good correlation with mapped lithologies, and gold mineralization is spatially associated with elevated K/Th- (or low Th/K-) and U/K- ratios. Gold mineralization is structurally controlled and mainly occurs in steeply dipping sulphide-bearing quartz-carbonate veins which are typically hosted in plagioclase amphibolite and tremolite-actinolite schist. The Werner solutions reveal that gold mineralization is structurally associated with both the dykes and lithological contacts. The laboratory results show anomalous gold concentrations ranging from 0.022 to 2.26 ppm, and thin section examination showed that gold mineralization is mainly associated with carbonate-sericite-pyrite-silica alteration. The mobile elements such as As, Te, Cs, Cr, Cu and Zn show close association with gold and are considered as suitable pathfinder elements for gold mineralization in the study area. The result of this research will contribute onto address the knowledge and understanding of geological controls of gold mineralization in Tumbelo area and nearby areas with similar geology.
Assessment of structural evolution of the southern kilombero rift basin, Tanzania: Implications for hydrocarbon potential
(The University of Dodoma, 2023) Richard, G.
In recent years, rift basins, including the southern Kilombero basin, have gained significant interest due to the discovery of oil in the East African Rift System, include the Albertine graben in Uganda and the Lokichar basin in Kenya. Although the southern Kilombero rift basin has been little studied using few widely spaced 2D seismic lines, there is a lack of detailed information regarding the structural pattern and kinematics, as well as their relationship with the southern Kilombero rift border fault. Therefore, this study focuses on the structural evolution of the southern Kilombero rift by conducting morphostructural and paleostress analysis to establish important fault parameters, including the current rift kinematics. The study uses SRTM-DEM, fieldwork, literature reviews, seismic interpretation and sandbox modeling in order to simulate the faulting sequences and their pattern with time. The results of the morphostructural analysis have revealed that the southern Kilombero rift border fault is a nearly 100 km long, symmetrical rift segment characterized by vertical displacement ranging from 250 m to 1300 m. The current seismic activity in the area is controlled by NNW–SSE trending normal faults. The analysis and interpretation of the results of the modeled stress tensor indicate that the stress regime is predominantly extensional being characterized by normal faulting and a horizontal minimum stress axis of approximately (Shmin) 060˚, suggesting that the southern Kilombero rift is an oblique rift. The sandbox model reveals that the southern Kilombero rift basin is transitioning from a half-graben into a full-graben, signifying an essential structure for hydrocarbon accumulation, fluid migration and preservation. During syn-kinematics rifting, the extension of the border fault led to the formation of numerous minor structures, increased accommodation space, relay ramps, en-echelon fault segments and intrabasinal structures. These structures contribute greatly to the basin’s evolution. Correlation between the 2D seismic data and the sandbox model suggests that sandbox modeling outperforms seismic data in identifying and interpreting complex, minor and structural features in subsurface geology. The discovery is anticipated to motivate geoscientists to explore more potential hydrocarbon resources in the future for economic gain.
Characterization of feldspathic deposits at virundiko area, Gairo district in central East Tanzania: implication for industrial viability
(The University of Dodoma, 2023) Francis, V.
The Virundiko area is within the Mozambique belt which is highly occupied by metamorphic rocks mainly ganertiferous migmatitic biotite gneiss, within the pegmatites where big crystals of feldspar, mica and quartz are found. The pegmatite extends to about 15 to 20 meters thick. Partly, garnet amphibolite lithologies forms elongated lenses concordant to the main foliation of the area. Currently, there is no any study established regarding the suitability of feldspathic deposits within the area for industrial viability. Geochemical, mineralogical, physical and optical properties analyses are the techniques that have been used in this study to identify the industrial viability of the feldspathic deposits at Virundiko area in three sites namely KST1, KST2 and KST3). The ratio of K2O/Na2O in feldspathic deposits in all three sites is greater than 1, suggested that the traditional method of ceramic production. However, for saving cost modern technologies should be considered with the condition of minor mineral beneficiation to decrease the ratios of K2O/Na2O to be less than 1, this applies also in glass industries. It is stipulated that the feldspar deposit at Virundiko fits best in porcelain and high-voltage electroporcelain. Minor removal of coloring oxides (TiO2 and FeO2) should be done for white vitrified bodies such as white porcelain and glass. There is very low amount of calcium within the samples hence the deposits do not fit for electronics and biochemical equipments. The mineralogical analysis indicates that the samples are predominantly K-feldspar with big crystals of feldspar which ranges from 5cm to 20cm with few mica and quartz grains associated with positive geochemical analysis results suggestive for gemstones. Moreover, the physical tests indicate that, the minerals are of moonstone variety showing translucently milky white which are smooth when cut with durable without any fractures and cleavage joints. The feldspar minerals are moderately hard, the optical character of the samples displays adularescence phenomena with double refractive which add value to the beauty of these minerals when cut as a gem. Therefore, the results support that samples from all three sites fit for gemstone in a cabochon cut.
Mineralogy and geochemistry of the asanje iron ore deposit within the mayamaya-Hombolo belt, Dodoma region, central Tanzania
(The University of Dodoma, 2023) Joseph, Y.
The Asanje iron ore deposit is hosted in Precambrian volcano-sedimentary rocks in the Mayamaya-Hombolo Belt in Dodoma region, within the Lake Nyanza Superterrane. The iron ore extends in two parallel ridges trending northwest to southeast, each about 9 kilometres. Knowledge of deposit types, mineralogy and geochemistry of iron ore deposits in the region is missing. Mineralogical and geochemical studies were performed on the collected samples to establish the economic and industrial feasibility of the deposit. Twenty-four samples were collected in both ridges for X-ray fluorescence, optical microscopy, and X-ray diffractometer studies to understand ores' mineralogy and geochemical impurities. The petrographic study shows that iron ore was composed mainly of hematite, goethite and quartz, with bornite and covellite as minor minerals, which were also confirmed by the XRD results. Furthermore, the XRF data shows that ridges I and II differ in mineralogical composition. The average concentrations in wt% of impurities such as SiO2, Al2O3, P2O5 and S are 37.9, 0.9, 1.2, and 0.2, respectively. By comparison, Ridge II has greater iron content (30.5–87.3 = Avg. 64.66 wt% Fe2O3t), whereas Ridge I has an intermediate iron content (20.8–78.22 = Avg. 48.68 wt% Fe2O3t). On the other hand, the values of Vanadium and Titanium present in iron ore range from 0.03 wt% to 0.25 wt% and 0.03 wt% to 2.27 wt%, respectively. The iron ore toxic elements like arsenic and galena concentrations are within the tolerable rate. The Asanje iron ore resources findings are compared to other iron ore deposits worldwide to determine their economic potential. The comparison data demonstrate that the Asanje iron ore deposit is low to medium grade and is suitable for commercial exploitation as raw material for industrial use. More research is needed to determine overall area extension and total ore resources.
Reconstruction of the rift formation and kinematics for the evolution of the basins in the afar region
(2023) Nyarera, Nyangena D.
This study focuses on seafloor spreading and evolution of the Afar region since the Paleogene through an integrated investigation of magmatism, continental rifting and seafloor spreading processes. While previous studies have attempted to establish rifting initiation on a local and regional scale, none have simulated the exact timing of the Afar rifting, rift basin evolution and magmatism over time. The study utilized geophysical and geological data incorporated into Gplate software to establish the tectonic evolution of magmatism, the timing of initial continental rifting and the spatial-temporal evolution of magmatism over the past 65 Ma. Seafloor spreading rates were estimated and validated against magnetic anomaly profiles from published data. The findings reveal that magmatism started at 31 Ma and manifested in four episodes. The rifting between the Arabian and Somalian plates began at 19 Ma, leading to subsequent drift in varying velocities and directions. The Arabian plate initially moved northeastward before undergoing a significant counterclockwise rotation towards the north-northwest. In contrast, the Somalian plate initially moved south-southeast and later rotated counterclockwise towards the east. These movements can be attributed to tensional forces at plate boundaries, interactions with neighboring plates, and the influence of mantle convection. The Seafloor spreading rates in the region range between 12.29 mm/yr and 20.12 mm/yr and exhibited a dominant orientation of E-W direction. Seafloor spreading started ca.16 Ma and has continued to the Present. The study also has identified an average pole relative motion between the Somalian and Arabian plates at 10.5469N 35.1857E, with an average angular rotation of 0.5353°/Ma. Moreover, the spreading direction from the south pole show an average angle of less than 30°, indicating a shift from east to west. This work will aid in understanding the mechanisms that drive tectonic plate movement and assessing the role of volcanic activity and sedimentation in the potential development of hydrocarbon resources in the basins of the Afar region. Additionally, the findings provide valuable insights on the geological history and evolution of basins in the Afar region hence more integration studies are required to determine sedimentation rates, why the Arabian plate exhibited a higher rate of plate motion than the Somalian plate and also to evaluate the hazardous implications associated with high rates of plate rotations to safeguarding local communities and infrastructure.
Characterisation of Handali gold mineralization-Dodoma region, central Tanzania
(The University of Dodoma, 2023) Mallya, Godfrey J.
The study on the characterisation of gold mineralisation in the Handali area covers the aspect of gold hosting lithologies, structural control and elemental associations. Geophysical geological and geochemical techniques are used to establish the extent of gold mineralisation in the Handali area. Gold occurrences of Handali have shown an association with interpreted NW-SE shear structure that coincides with the linear magnetic low zone. Artisanal pit mapping and petrographic study of samples from these pits indicate that gold mineralisation is characterised by quartz ± feldspar veins/ veinlets in multiple zones confined to amphibolite. The main ore minerals are pyrite and chalcopyrite, with insignificant content of bornite and covellite. Alteration minerals are chlorite and sericite. Analytical results of rock samples from Artisanalpitsshow0.2 g/t Au in amphibolite, while sulphide-bearing quartz ± feldspar vein amphibolite returned up to 8.5 g/t. Gold concentration in the rock samples show moderate to strong correlation with Cu, As and W as shown by Pearson Correlation coefficient and Hierarchal Cluster Analyses (HCA), indicating this element suite is potentially proposed to be used as pathfinder elements for future exploration of gold. Geochemical results of soil samples returned gold anomalous values of up to 0.123ppm.Principle Component Analysis (PCA) of soil geochemical data shows that Fe, Cu and Zn are the main pathfinder elements while searching for gold in the area. The bubble plot of Au values generated from soil geochemical data delineates NW-SE and defines new NE-SW trending patterns extending Handali-type gold mineralisation. Lithological, structural and geochemical studies demonstrate the relationship between lithology, structure and gold mineralisation. Soil sampling and detailed structural mapping are recommended before any attempt to conduct drilling to the Handali prospect.
Mineral prospectivity modelling to delineate potential areas for gold deposits: a case study of the Lupa goldfield, South West Tanzania
(The University of Dodoma, 2023) Ngowi, Dickson E.
Conventional methods for exploring mineral deposits are becoming difficult to locate undiscovered deposits because their capability to find out concealed ore deposits is limited. New sophisticated methods are required for analyzing and integrating various geoscience datasets to locate new deposits. The aim of this study is to delineate prospective areas for gold deposits in the Lupa Goldfield by using weight of evidence model. The weight of evidence is a data-driven method for mineral prospectivity mapping that uses conditional probabilities to determine the relative importance of individual layers of evidence. The method establishes a spatial relationship between known mineral deposits and evidential maps to create a mineral prospectivity map. In this study, four evidential maps derived from geochemical, geological, geophysical and remote sensing datasets including a training sites layer of 64 mineral occurrences were generated and integrated to produce mineral prospectivity map. The results of this study indicate that; mafic and metamorphosed mafic rocks intruded by granitic rocks, proximity to faults, presence of geochemical gold anomaly and high magnetic anomaly were the primary geological features for recognizing gold mineralization in the Lupa Goldfield. The model results have revealed 5 classes ranked from the highest, high, medium, low and lowest favorability patterns with probability values; 0.051, 0.0426, 0.0225, 0.0172 and 0.0091 respectively. The highest favorable areas have the best gold potentials based on the presence of predictor patterns from all the four evidential maps. The model was evaluated and validated of which the results have revealed that, the use of weight of evidence model is successful and useful to locate prospective areas for gold deposits in the study area.
Delineation of lithologies and subsurface structures related to gold mineralization in Kibati prospect Mvomero, Morogoro: Implications for gold exploration
(2023) Balambirwa, O
Structures, lithologies, and potential zones and their relationship to gold mineralization were investigated to decipher the controls of gold mineralization at the Kibati Gold Prospect. The structures and lithologies were investigated through the interpretation of high-resolution aeromagnetic data, ground magnetic data, geological mapping, and rock sampling. Aeromagnetic results reveal the presence of two structural systems that trend in NW-SE and NE-SW, whereby the NW-SE is the dominant control of gold mineralization. The subsurface structure with NW-SE trending controls the mineralized fluids as a consequence of gold mineralization in the surface lithologies. Results from the detailed investigation in two blocks A and B within the study area show that most of the structures trend in the NW-SE direction. Petrography and field observations show that granitic gneiss, garnet biotite quartzo-feldspathic gneiss, dolerite and amphibolite are the main exposed outcrops. The quartz vein shear zone hosted with hematite-limonite is associated with auriferous veins characterized by gold values ranging from 0.004 to 19.680 g/t. Exposed quartz veins in the northern part of the Kibati area also returned gold values of up to 0.623 g/t. The gold anomaly is persistent and collinear with the NW-SE trending structures delineated from magnetic maps. The trend of the structures in blocks A and B overlaid with gold anomalies range from 0.0623-4.419 g/t and 10.19-19.680 g/t respectively, which confirm the target zones located within shear zones hosted quartz vein striking NW-SE of Kibati prospect. These structures, therefore, act as conduits where gold precipitated in minor/local structures in blocks A and B.
Reconnaissance exploration for gold in the Misaki area within the Iramba-Sekenke greenstone belt, central Tanzania
(The University of Dodoma, 2020) Maganga, Zortosy Mpangile
Combinations of geological, geophysical and geochemical techniques have been used to explore gold deposits at Misaki within the Iramba-Sekenke Greenstone Belt (ISGB) in Singida region. The Misaki area is occupied by different rocks including homogeneous coarse-grained granite containing numerous xenoliths (> 5 vol. %), tonalite, K-rich granite and pegmatite, and dolerite dykes. All granitic rocks have been intruded by dolerite dykes, cut by epidote veins and are found juxtaposed to a tonalitic rock. Granitic rocks contain mainly anhedral to subhedral K-feldspar, plagioclase, quartz, biotite, hornblende, muscovite and opaque minerals, whereas tonalite contains similar minerals with relatively large amounts of plagioclase, biotite and hornblende (> 10 wt. %) and no K-feldspar. The rocks are weakly foliated to massive and poikilitic. K-feldspar is perthitic, whereas plagioclases have cores with rim overgrowths. Chlorite, plagioclase, epidote and sericite in the rock formed at the expense of primary minerals under greenschist facies conditions. Aeromagnetic data managed to identify lineaments that crosscut different rocks, from which NE-SW, NW-SE and ESE-WNW trends have been recognized. Results from radiometric data mapped different lithological units by their different K, U and Th contents distinguishing areas occupied by sediments or sedimentary rocks and those underlain by granitoid rocks. Soil geochemical survey has identified gold anomalies of up to 0.2 ppm Au that in parts associated with NE-SW trending lineaments. A follow-up detailed geological mapping work is recommended that would involve trenching and sampling of unweathered rocks, and documentation of geological structures to uncover potential gold deposits of the Misaki area within the Iramba-Senkenke Greenstone Belt (ISGB).
Land use land cover changes, water quality and locals’ involvement in conserving Kihansi spray toads (Nectophrynoides asperginis), in Kihansi Tanzania
(The University of Dodma, 2021) Sigala, Atuhombye
Biodiversity hotspot areas host global potential for the conservation of wildlife species particularly those that are endemic and critically endangered. This study focused at assessing the land use land cover change (LULCC) of Kihansi catchment and adjacent areas, water quality along the Kihansi River and the involvementof local communities on the conservation of the Kihansi spray toads (KST)(Nectophrynoides asperginis). Landsat images were used to classify and monitor LULCC for 25 years from 1995 to 2020. Also, water quality of KihansiRiver was assessed in terms of pH, turbidity, dissolved oxygen (DO), temperature, total dissolved solids (TDS). Semi-structured questionnaires were used to collect data from the respondents from three adjacent villages namely: Mgugwe, Udagaji and Ukami. Settlements and agricultural land increased by 26.23% and 3.7%, respectively. On the other hand, forest land decreased by a rate of 1.2% per yearbetween 1995 and the year 2020.Cultivation of crops such as paddy and maize were the dominant socio-economic activity (p<0.05). Significant variation for water quality variables was observed (p<0.05) for temperature (Mean ± S.E=25.34±0.31oC), pH (Mean ± S.E.=6.88±0.03) and DO (Mean± S.E. =5.41±0.03 mg/L) among the three sampled zones while human activities such as agriculture significantly influenced water quality (p<0.05). About 98.9% (n=361) of local communities wereheard about KST and the variation across villages was significant (p<0.05). Also 46.03% (n=168) have seen the toads although only 27. 67% (n=101) were able to identify the toads through their physical features. Human activities influence LULCC of KC thereby threatening the KC ecosystem and KST due to habitat loss. Ifnoproper measures are taken for management of the Kihansi River continued increase of TDS from human activitieswilldecreases DO in water, thismay threaten sustainabilityofthe re-introduced toads.This study provides baseline information for land use planning in KC and adjacent areas that consider sustainable conservation of the re-introduced KST which includes establishment of buffer zone around the catchment. It also calls for proper management of the Kihansi River through involvement of local communities to ensure sustainability of the re-introduced KST.Local communities should be involved in conservation activities like habitat restoration and research activities on the re-introduced KST throughconservation education, and outreach programs.
Characteristics of graphite mineralization and it’s exploration potential in Chenjere area Ruangwa district south eastern Tanzania
(The University of Dodma, 2021) Moye, Charles Daniel
Electromagnetic and magnetic surveys, geological mapping, trenching, drilling and geochemical analysis were carried out in the Chenjere area to investigate the graphite characteristic and the exploration potential of graphite mineralization. Mtimbo, Matochi, Ng'imbwa, and Nakapelo were discovered to have graphite potential using these approaches. Loss on ignition (LOI) and infrared spectroscope (IR) analysis revealed graphite grades ranging from 4 to 8 wt.%. The graphite zones have thicknesses of 13 to 29 m and strike lengths of 1 to 4 km. The study has revealed that the graphite mineralization zones are concordant with the prominent strike of NE to SW. The electromagnetic signals have shown a positive correlation with the graphite mineralization as the high conducting bodies are coinciding with the graphite mineralization. This is proven by samples from trenching and drilling analysed by the IR method. Petrographic studies have confirmed that the graphite encountered is of flake type disseminated in the host rock of graphitic gneiss. Flakes showed dip-slip lineation similar to those of hosting rocks. Based on the field observation, electromagnetic survey, graphite grade, petrographic studies and comparison with the renowned graphite deposits the Chenjere graphite is of sedimentary origin. The graphite flakes are coarse ranging from 50 to 1000 µm. The lath shape flakes had inter growth with silicate gangue minerals with no overgrowth. The graphite flake size, the grade and the extension are warranting for the economic exploration potential in the Chenjere area
Analogue sandbox modelling of the Western Subbasin, Melut Basin, South Sudan: strike-slip tectonic implications for rifting and fault sequences
(The University of Dodma, 2021) Duot, John Bior
Melut basin is a passive rift basin that contains numerous oil-rich rift sub-basins, and it has experienced many strike-slip effects from the Central African shear zone. The multi-directional stresses of strike-slip settings have made western sub basin architecture and fault sequences complex and difficult to understand. The lack of practical structural data might have been one of the reasons for the challenging discoveries of oil and gas in the study area. Therefore, it is essential to deepen the structural data adequacy. The objective of this study is to characterize strike-slip tectonic implications for rifting and fault sequences responsible for the creation of accommodation spaces of Melut rift episodes by using analogue sandbox modelling-assisted approach to promote future exploration in the Melut Basin. Analogue modeling as a method used scales of time and length to model geodynamic evolutions. To enhance structural data adequacy, the experiments were carried out at the laboratory and set with the same basement offset 5.3cm/2.9cm, 158°/151°stepovers in the releasing and restraining bends. The analogue modelling rig was set to be displaced by the computer-controlled motor at a rate of 5mm/2min with 65mm dextral displacement motion. The analysis was done using the top views and vertical sections from the models. The experimental results show delimited uplifts and extensional collapses characterized by oblique faults with normal and thrust components, well deformed pull-apart basins, and redistributed accommodative structures for ExpS1, ExpS2, and ExpS3 respectively. The study found out that the first rift phase reflect large and subsided sedimentary layers filled by 15 mm (1.5 km in nature) and accommodated by the two normal bounding faults while the second rifting revealed less tectonic subsidence filled by 9 mm (0.9 km in the nature) deposits and held by normal bounding and tilted faults, and lastly the third rifting showed the bounding normal fault and the oblique fault with a normal component filled by 6 mm (0.6 km in the nature) sediments thickness. The exhibited trans-tensional pull-apart basin and positive flower structures display economic importance. The findings of this study are useful in the future exploration and production of oil and gas in the study area. Semi-regional seismic and extensional modelling studies are recommended to illuminate structural styles.
Geochemical evaluation and correlation of source rocks, crude oils and oil seepage. A case: Albertine Graben, Uganda
(The University of Dodoma, 2021) Majorine, Namaganda
Geochemical evaluation and correlation of source rock samples, crude oils and oil seepage samples was carried out in the Albertine Graben, Uganda to establish the existence of a genetic relationship between the Graben’s source rocks and the crude and seepage oils. Evaluation of samples was carried out using data from pyrolysis analysis of samples, while the correlation of samples was based upon the recognition of unique patterns from biomarker analysis. The study involved one (1) seepage, two (2) source rock samples, and five (5) crude oils from Mputa, Kingfisher, Gunya, Ngiri, and Job-Rii wells. The TOC values of the source rock samples ranged from 1.25 to 7.2%, implying that the source rocks had a high potential to generate hydrocarbons. Furthermore, source rock samples with TOC ≥ 0.5% were also evaluated for petroleum potential using petroleum indices of Tmax, S1, S2 and HI. The source rock samples Tmax values ranged between 432 and 447°C, implying that the source rock maturities were within the oil window. The S1 and S2 parameters ranged from 0.02 to 1.78 mg/g rock and 0.87 to 37.71 mg/g rock, respectively, implying that the genetic potential of the source rock samples varied from poor to excellent. Additionally, the HI values ranged between 65 and 523 mgHC/gTOC, implying that the source rock samples were composed of kerogen types II, II/III, and III. Biomarker (terpanes (m/z 191) and steranes (m/z 217)) analysis, pristane/phytane ratios and n-alkane distribution were also performed on source rock samples, seepage, and crude oil samples. The results show that the source rock samples, seepage and crude oils were derived from mixed organic matter dominated by algal deposited in a sub-oxic depositional environment. Oil-oil and oil-source correlation using cross plots and ternary diagrams of steranes and terpanes, indicated that there was a correlation between the crude oils and the oil seepage based on sterane analysis. However, no correlation was observed between source rock samples, and crude oils and oil seepage. Based on terpanes analysis of the study samples, a correlation was exhibited between only one source rock sample (SRE 2) and the crude oils samples. However, there was no correlation shown by all the three study samples: source rock extracts, crude oil, and seepages. The findings of this study will aid in further research and development programs as well as guide the Uganda’s petroleum regulatory authorities and exploration companies on the hydrocarbon potential of the Albertine Graben.
Petrophysical analysis of the red sandstone group of The Rukwa Graben, Southwestern Tanzania
(The University of Dodma, 2021) Ojok, Tonny
The study of various well-logs aids in the identification of potential sand and reservoir zones and their thicknesses within a formation. The current study addressed the lack of research and literature on the petrophysical properties and reservoir potential of the Red Sandstone Group (RSG) Formation in the Rukwa Basin, southwestern Tanzania. This study presents the findings of the petrophysical analysis of the RSG Formation in the Rukwa Rift Basin. The Techlog computer program was used to analyse the Ivuna-1 well-log suite, comprising of the caliper, gamma-ray, neutron, and density logs and the Galula-1 well-log suite comprising of gamma-ray, spontaneous potential, resistivity, and sonic logs. Based on the petrophysical analysis, five sand zones were delineated in each well: (A-E) in the Galula-1 well and (1-5) in the Ivuna-1 well. According to this study, the RSG in both the Galula-1 and Ivuna-1 wells is dominated by clastic facies with interbedded thin shale and was most likely deposited in fluvial and fluvio-lacustrine environments. The delineated sand zones in Galula-1 well have shale volumes ranging from 28.8% to 36.1%, high effective porosities ranging from 30.1% to 32.6%, high permeabilities ranging from 88.45 mD to 121.39 mD, 100% water saturation, and no hydrocarbons. The five delineated reservoirs in Galula-1 well have high effective porosities ranging from 25.8% to 28.8%, high permeabilities ranging between 45.92 mD and 71.91 mD, and are 100% water saturated but lack hydrocarbons. As a result, the RSG of the Galula-1 well was assessed to have good petrophysical properties and is a potential hydrocarbon reservoir given the presence of hydrocarbons. By contrast, the delineated sand zones in Ivuna-1 well have shale volumes ranging from 26.4% to 35.6%, very low effective porosities ranging from 0.011% to 0.038%, and poor permeabilities ranging from 0.007 to 0.117 mD. Further, the two delineated reservoirs in Ivuna-1 well are thin and have very low effective porosities ranging between 0.112% and 0.106% and poor permeabilities ranging between 1.33 mD and 1.64 mD. Consequently, the RSG of the Ivuna-1 well was evaluated as having poor petrophysical properties and is not a suitable hydrocarbon reservoir. This study also revealed that the porosity and permeability of the RSG declines greatly from the Galula-1 well to the Ivuna-1 well. Nevertheless, more research is recommended to validate this revelation. This study further, recommends more research into the porosity and permeability of the RSG through petrography and core analysis. The findings of this study will contribute to academic, geologic, geophysical, and hydrocarbon research of the RSG and Rukwa Basin at large.
Reconnaissance exploration for gold in the Misaki area within the Iramba-Sekenke greenstone belt, central Tanzania
(The University of Dodoma, 2020) Maganga, Zortosy Mpangile
Combinations of geological, geophysical and geochemical techniques have been used to explore gold deposits at Misaki within the Iramba-Sekenke Greenstone Belt (ISGB) in Singida region. The Misaki area is occupied by different rocks including homogeneous coarse-grained granite containing numerous xenoliths (> 5 vol. %), tonalite, K-rich granite and pegmatite, and dolerite dykes. All granitic rocks have been intruded by dolerite dykes, cut by epidote veins and are found juxtaposed to a tonalitic rock. Granitic rocks contain mainly anhedral to subhedral K-feldspar, plagioclase, quartz, biotite, hornblende, muscovite and opaque minerals, whereas tonalite contains similar minerals with relatively large amounts of plagioclase, biotite and hornblende (> 10 wt. %) and no K-feldspar. The rocks are weakly foliated to massive and poikilitic. K-feldspar is perthitic, whereas plagioclases have cores with rim overgrowths. Chlorite, plagioclase, epidote and sericite in the rock formed at the expense of primary minerals under greenschist facies conditions. Aeromagnetic data managed to identify lineaments that crosscut different rocks, from which NE-SW, NW-SE and ESE-WNW trends have been recognized. Results from radiometric data mapped different lithological units by their different K, U and Th contents distinguishing areas occupied by sediments or sedimentary rocks and those underlain by granitoid rocks. Soil geochemical survey has identified gold anomalies of up to 0.2 ppm Au that in parts associated with NE-SW trending lineaments. A follow-up detailed geological mapping work is recommended that would involve trenching and sampling of unweathered rocks, and documentation of geological structures to uncover potential gold deposits of the Misaki area within the Iramba-Senkenke Greenstone Belt (ISGB).
Structural and sequence stratigraphic framework of Lukuliro area, southernpart of Rufiji trough
(The University of Dodoma, 2018) Marwa, Fredrick M.
This study conducted within southern parts of Rufiji Trough include Lukuliro area which has been potential target for oil and gas exploration since 1980’s years. Within Rufiji trough, the discovery of Wingayongo seeps (onshore) and SongoSongo gas (offshore) attract attention on exploration activities within Rufiji trough. The previous works conducted within Lukuliro area failed to establish traps which are well demonstrated in this study. The structural and sequence stratigraphy framework were established through interpretation of six old 2D seismic data and well data from Lukuliro 1 well by using Petrel version 2013. During this investigation interesting structural features that were revealed to occur within Lukuliro area were including faults such as Listric faults, tilted growth faults, wrench faults and flower structures and small-scale folded structures (anticline). The major faults within Lukuliro area revealed to be oriented in NNE-SSW, NNW-SSE and E-W directions. These faults interpreted from different seismic sections within the study area revealed to form good structural traps. The interesting structural traps suggested to be developed within tilted faulted bocks adjacent to wrench faults and also within flower structures. Structural trap configuration revealed to be constrained by Mtumbei limestone reservoir which became sealed by shale, mudstone, and claystone and siltstone lower Kipatimu formation. However, the structural traps seem to be dominant within Lukuliro area but also the potential stratigraphic features revealed from well log interpretation and sequence stratigraphy interpretation including channel infill, unconformities, toplap and clinoforms are responsible for occurrence and accumulation of hydrocarbons.
Sediments thickness and structural framework of lake Natron basin and their implications for hydrocarbon potentiality
(The University of Dodoma, 2018) Godfrey, Grace
Lake Natron is among the basins of the Eastern branch of the East African Rift located in Northern Tanzania. The main objective of this study was to establish the spatial variation of sediments thickness and to delineate the subsurface structures that control the configuration of the basement and their implications for hydrocarbon potentiality. The study utilized both aeromagnetic and gravity data in achieving the objectives. Two dimension gravity modelling, Euler deconvolution of aeromagnetic data and spectral depth methods were used to determine the thickness of sediments. The structural interpretation of gravity and magnetic data were done by applying processing techniques to the observed data. These techniques include Reduced to pole, Analytic signal, Goussav filter and vertical derivatives of aeromagnetic data. The interpretation suggested that the Natron basin is bounded by fault systems, which are mainly trending NE-SW, NW-SE and NS directions. The estimated depths found to the deeper source of 3.18 km and 4.01 km for the aeromagnetic and gravity data, respectively. These depths found on the northern part of the Lake Natron basin. The thickness of sediments decreases from 3.18 km in the northern part of the basin to 2.75 in the southern part using aeromagnetic data. The results from Euler Deconvolution revealed the maximum depth to basement was ranging from 3 km to 3.5 km. Also the results from Euler Deconvolution showed that the study area has different faults/lineaments mostly trending in the NE-SW direction. The results from gravity modelling have shown the variation of sediments thickness ranging from 1.24 km to 4.01 km within the lake basin. Based on these results the northern part of the study area shows the potentiality of hydrocarbon. Integration of both gravity and magnetic data used in this study with seismic data can assist to confirm the potentiality of hydrocarbon in the lake Natron basin.
A study of petrophysical properties of the lake beds of the Rukwa basin based on well log data
(The University of Dodoma, 2017) Mtango, Zephania Grayson
Well logging is the practice of making a detailed record of the geologic formations penetrated by the well. The key purpose of well logging is to obtain petrophysical properties of reservoirs such as porosity, permeability, hydrocarbon saturation etc., for hydrocarbon exploration. Logs also tell us about the fluids in the pores of the reservoir rocks. Petrophysical parameters such as effective porosity (Φ), water saturation (Sw), formation water resistivity (Rw), hydrocarbon saturation (So) and formation resistivity (Rt) is evaluated by using the well log data. In the present study, an attempt has been conducted to describe the application of various open-hole logging tools such as gamma ray, sonic, resistivity and calliper logging tools to determine the petrophysical properties of Lake Beds. The present study portrays the interpretation of well log data using the open hole logs in parts of Rukwa Basin. Well log analysis has revealed a range of formation water resistivity (Rw) of 0.0032 Ω-m throughout the well indicating the presence of water-bearing sands in the Lake Beds. Based on Logs (GR log mostly) the Lake Beds were zoned into 6 zones; named A, B, C, D, E, & F in Galula.1 The six zones are identified by using logs at the depth of (7.8 - 256) m, (256 – 354.8) m, (354.8 – 461.5) m, (461.5 – 554.1) m,(554.1- 702.5) m, & (720.5 – 959.2) with average shale volume of (27% - 46.1%), average porosity (10.6% - 17.5%), average water saturation of (22.2% - 33.6%) and average permeability of (0.34mD – 8.6mD) . In both wells Ivuna.1 and Galula.1 the Lake Beds succession in Rukwa basin revealed through this study to have promising porosity for Gas accumulation. However, these zones are found in a very shallow depth with low permeability.

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