- Title
- Tectonic and structural aspects at the Otjihase Mine, Matchless Belt, Namibia: A Systematic Review
- Creator
- Hartmann, K
- Subject
- Uncatalogued
- Date Issued
- 1995-04
- Date
- 1995-04
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10962/190232
- Identifier
- vital:44976
- Description
- The Otjihase pyritic massive sulphide deposit occurs within a 10km thick metasedimentary sequence of the Kuiseb Formation. The Kuiseb metasediments were deposited within the Khomas Trough, which forms the southernmost rift of the intracontinental arm of the Damara orogen. Amphibolite units of the Matchless member at Otjihase have a MORB-type geochemical character and occur within the Kuiseb schists, about 200m above the ore zone. The Otjihase mine is the largest of many Besshi-type deposits that occur in close proximity to the Matchless amphibolites. A depositional environment in a rift, slightly more advanced than the present-day Red Sea is envisaged. The five parallel, ruler-shaped, mineralised shoots at Otjihase occur on the same stratigraphic level. They have a plunge of approximately 6° to the west and a dip of approximately 16° to the northwest. The largest and best mineralised, is the northernmost shoot (the Main Shoot) which is ±250m wide, up to 12m thick and has a known length of 7,5km. The large length/breadth ratio is ascribed to the original setting along faults and thickening of the ore zone during thrusting. Intense ductile deformation has affected the ore bodies, with isoclinal refolding, boudinaging, duplexes of more competent bands and smearing of the schists. Squeezing and remobilisation of the sulphides into the schistosity and low pressure pods has taken place. Successive folding and thrusting during the D2 deformational event resulted in the dominant structural style. Fold axes of drag folds plot onto a great circle in stereographic projection, indicating the formation of sheath folds. The axial planar cleavages of competent layers is steeper than the S(0,1) foliation and suggests a structural right way-up. The presence of chloritic alteration above the ore shoots, is suggestive of footwall alteration indicating that the sequence was overturned during the D1 deformational event. Ore zone lithologies include stringery-, massive- and semi-massive sulphides, mineralised magnetite- quartzites and disseminated sulphide mineralisation within quartz-biotite-chlorite schists. Chalcopyrite is the main economic mineral and mainly occurs as matrix to pyrite and in coarse-grained pods. Lithological and metal zoning within the Main Shoot is distinct and is an indication that the macroscopic shape of the orebody is largely unaffected by later ductile deformation. North-south trending normal faults of the Windhoek Graben have disrupted the continuity of the ore shoots. In section, the faults appear to have a listric shape. The major faults have pronounced scissor movements and as a result the dips of the blocks within fault zones are affected.
- Description
- Thesis (MSc) -- Faculty of Science, Exploration Geology, 2021
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (109 pages)
- Format
- Publisher
- Rhodes University
- Publisher
- Faculty of Science, Exploration Geology
- Language
- English
- Rights
- Hartmann, K
- Rights
- Attribution 4.0 International (CC BY 4.0)
- Rights
- Open Access
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Hartmann-MSC_TR17.pdf | 6 MB | Adobe Acrobat PDF | View Details Download |