Copper
Project Name: |
KIGOMA WEST & KIGOMA EAST |
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Location: |
Kigoma West and Kigoma East |
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The licences are located approximately 120km due east of the town of Kigoma and situated approximately 200km (5 hours drive) north of Mpanda. Kigoma West lies close to Malagarasi within the Mpanda District, and Kigoma East is located near Ilunde in the Kigoma District. |
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Chunya |
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This licence is located approximately 110km north of Mbeya, close to Lupa within the Chunya District. |
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Area: |
Kigoma West |
687.02km2 |
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Kigoma East |
735.60km2 |
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Chunya |
433.33km2 |
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Access:
Kigoma Licences.
The two licences are contiguous, located immediately adjacent to each other. The Main town of Kigoma lies 120km to the west on the shores of Lake Tanganyika. The main east-west railway line linking the Lake Tanganyika region with Dar es Salaam, to the East runs across the northern section of both Kigoma licences. Kigoma has an airport and ferry port facility.
Chunya
The licence lies approximately 110km north of Mbeya, within the Chunya District. Mbeya is a large town serviced with a gravel air strip and lies on the main Dar es Salaam to Lusaka (Zambia) road. Access to the licence is via bush roads from the main road that runs north from Mbeya towards the Lake Victoria Goldfields and Mwanza.
Geology:
Kigoma Licences
Typically the northern 30% of both licences is covered recent Neogene alluvials and soils. The basement of Ubendian aged gneisses is overlain by shales and silts, with sandy intercalations of the Bukoban-aged Nyanza shale. The predominant unit from historical geological data is the Malagarasi sandstone which consists of medium to coarse grained cross bedded sandstone with occasional thin shale horizons. Generally outcrop within both licence areas is poor.
View across the Kigoma Licences
Chunya Licence
As with both Kigoma licences, outcrop is poor, with much of the Chunya licence covered by Neogene soils and alluvial sediments, with topographic highs being defined by inliers of the Precambrian Ilunga granite.
Float littering the slopes of Kasasi Hill, Chunya Licence
Historical mapping also indicates a number of shear zones have been identified trending between northwest to southeast and north to south, which are defined by prominent ridges formed of resistant silicified and ferruginous fault breccias. Massive ironstone has formed in the shears by hematite replacement of fault breccias and former porphyritic dyke rocks. The granitic rock marginal to the shears are sericitized and silicified.
To the northwest a series of ridges formed by massive quartz reefs follows south westerly trending faults. Large amounts of milky and clear quartz were found as float in the licence area along with several large quartz veins with fracture filling iron oxide between the quartz and country rock.
Quartz veining with iron oxide lined fractured
The Lupa Goldfield lies almost immediately south of the Chunya licence, with 24 tonnes of gold produced historically from 80 placers and lode deposits. Quartz lode mining began at Ntumbi, which is 20km south from the Chunya licence. Within the goldfield the gold and sulphide mineralization is known to occur within shear zones and ENE and north-south trending quartz reefs.
Commentary on the Copper Licences (based on the CPR; WAI 2008)
Not known for its copper deposits, to date, Tanzania has been historically underexplored for copper, unlike its neighbors, the Democratic Republic of Congo and Zambia. There are two deposit styles that potentially relate to the Chunya and Kigoma properties respectively; IOCG (iron oxide copper gold) and stratiform or sediment hosted copper deposits.
1. Iron Oxide Copper Gold Deposits
Iron oxide-copper-gold (IOCG) deposits, is a category applied to a wide range of sulphide poor, low titanium, magnetite-rich and/or hematite deposits usually of hydrothermal origin in the form of ore-bearing breccias, veins, and disseminated and massive lenses with a Cu-Au-Co-Ni-As-Mo-U-(LEE) signature. Deposits are recognized by their elevated magnetite and/or hematite content and are usually more than 20% iron oxide. The deposits are formed in association calcic-sodic regional alteration (>1km) superimposed on more localised potassic alteration demonstrating a shallowing and outward zonation from magnetite-actinolite-apatite to specular hematite-chlorite-sericite; massive calcite veins and barren pyritic feldspar destructive alteration may be indicators of IOCG deposits beneath cover (Corriveau, 2005).
Literature indicates that structurally controlled IOCG deposits commonly share normal faults and fractures with pre-mineral mafic dykes; numerous doleritic dykes have been mapped to the south of the licence throughout the Lupa goldfield, which may be significant in terms of timing of mineralisation.
Furthermore, the ironstone bands have been mapped as near vertical tabular bodies; these could possibly be a replacement of dyke structures. Some IOCG vein deposits have been found to be hosted by intrusive rocks such as those found within the licence.
2. Sediment Hosted Copper Mineralisation
Sediment-hosted copper deposits encompass some of the richest and largest copper deposits in the world including copper deposits of the Zambian Copper Belt, which have produced in excess of one billion metric tons of copper at an average grade of approximately 2.7 wt. percent copper, as well as significant quantities of cobalt and silver (Hitzman et al, 2005).
Sediment-hosted copper deposits are formed by the mixing of an oxidised copper-carrying brine and a reduced fluid that may have formed where there had been anaerobic sulphate reducing bacteria, such as those found in shales. The mixing occurs in permeable sedimentary and (less commonly) volcanic rocks. The following conditions are required:
- (1) an oxidized source rock,
- (2) a brine to mobilize copper
- (3) a reduced fluid to precipitate copper
- (4) conditions favourable for fluid mixing
These deposits are usually restricted to a narrow range of layers within a sedimentary sequence but do not necessarily follow sedimentary bedding; commonly they are deposited prior to lithification of the host rocks, which comprise two types: calcareous or dolomitic siltstone, shale, and carbonate rocks of marine or lacustrine origin; and non marine sandstone, arkose, and conglomerate, such as occurs across the southern sector of the Kigoma licences.
Preliminary observations during a reconnaissance site visit to the Kigoma and Chunya properties, indicates the areas do have several features indicative of known sediment hosted copper deposits and IOCG deposits respectively, although no ore mineralisation was observed.