- Title
- The geology and alteration-mineralisation of the Gamigab Tin Prospect, Damaraland, Namibia
- Creator
- Walraven, Felix Caspar
- ThesisAdvisor
- Jacobs, R.
- Subject
- Mineralogy -- Namibia -- Damaraland
- Subject
- Geology -- Namibia -- Damaraland
- Subject
- Tin mines and mining -- Namibia -- Damaraland
- Date
- 1990
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- vital:4956
- Identifier
- http://hdl.handle.net/10962/d1005568
- Identifier
- Mineralogy -- Namibia -- Damaraland
- Identifier
- Geology -- Namibia -- Damaraland
- Identifier
- Tin mines and mining -- Namibia -- Damaraland
- Description
- The stratigraphy at the Gamigab Sn prospect consists of two mainly schistose units separated by a thick marble unit which have been assigned to the Orusewa, the Karibib and the Kuiseb Formations respectively. Four phases of folding affected the lithologies with the south-south-west trending F2 folds defining the main structures in the region. The area underwent low grades of metamorphism. Temperatures were in the range 420° to 500°C and pressures less than 2 kbars. The effects of contact metamorphism are seen in the south-east and south-west. Regional metamorphism outlasted the deformation and contact metamorphism started late during deformation. Two Karoo-age intrusions penetrated the metasediments north of the mineralisation. One is an altered porphyry plug and the other is a weathered dolerite plug, the latter containing xenoliths of undeformed Karoo sediments. Cassiterite is hosted within east-west trending quartz veins that cross-cut previously altered schistose country rocks. The alteration types include sericitisation, tourmalinisation, carbonatisation and ferruginisation. Preliminary Rb/Sr dating on muscovite from the alteration zone suggests an age of 509 ± 11 Ma. Breccias of probable hydrothermal origin are spatially associated with the mineralisation. These hydraulic breccias occur in antiformal structures within the marble and developed in response to a sudden pressure release due to a build up of fluids at the contact between the schistose Orusewa and carbonate Karibib Formations.
- Format
- 162 p., pdf
- Publisher
- Rhodes University, Faculty of Science, Geology
- Language
- English
- Rights
- Walraven, Felix Caspar
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