Southwest Africa

Phosphorite deposits are currently forming in areas of high organic productivity and low detrital input. These are typically coastal upwelling zones adjacent to arid continental lands. Phosphorites form at slow rates, so low detrital input is important to prevent dilution or burial. As shown in Figure 18.10, sites of formation include the continental margins of Peru, Chile, and southwest Africa. 

Hartleb, J.W.O. 1988. The Langer Heinrich uranium deposit, Southwest Africa/Namibia. Ore Geology Reviews, 3, 277-287. 

According to J. Papish and C. B. Stilson, the zinc minerals sphalerite, gahnite, hopeite, parahopeite, and adamite all contain gallium (44, 46). It has also been detected spectroscopically in certain French, Spanish, and Japanese mineral waters (47, 48). Germanite from Tsumeb, Southwest Africa, contains from 0.57 to 1.85 per cent of gallium and is thus a rich source of this rare metal (44,49). 

Heckroodtand Roering (1965) mixed-layer chlorite-swelling chlorite hydrothermal alteration of beryl, Karibib, Southwest Africa analysis recalculated to 100% analysts P.J. Fourie, C.F.G. Schutte and A.F. Hogg. 

Romankevich, Ye.A. and Baturin, G.N., 1972. Composition of the organic matter in phosphorites from the continental shelf of southwest Africa. Geochem. Int., 9 464— 470. 

Vasquez De Espinosa, A. Description of the Indies. Washington, D.C. Smithsonian Institute Press, 1960. (Originally published, ca. 1620.) Vedder, H. Southwest Africa in early times. New York Barnes and Noble, 1966. 

Phosphorites occur in organic-rich muds deposited on the shelf off southwest Africa, which are also enriched in certain minor metals that are not of terrigenous origin (30 p. 209-210). The metals in these sediments are within the ranges of the metal content of... 

Hensen C., Landenberger H., Zabel M., Gundersen J.K., Glud R.N. and Schulz H.D. (1997) Simulation of early diagenetic processes in continental slope sediments off Southwest Africa The copmputer model CoTAM tested. Marine Geology, 144 191-210... 

Fig. 6.16 Plots of (a) the ratio between diffusive oxygen uptake rates (DOU) ex-situ and in-situ and (b) oxygen penetration depth ex-situ and in-situ versus water depth from stations off the continental slope off Southwest Africa (from Glud et al. 1994). Solid lines indicate linear regressions. With increasing water depth fluxes appear to be overestimated and oxygen penetration underestimated when measured ex-situ.

Thus, it appears that there are highly unique environments in the upwelling area off southwest Africa providing the microbiological and chemical conditions for rapid diagenesis of steroids within a time scale of 100 years or less. Although these conditions exist in the sediments, they do not appear... 

Hobson, L.A., 1971. Relationships between particulate organic carbon and micro-organisms in upwelling areas off southwest Africa. Inv. Pesq., 35 195—208. 

A subsiding, very steep (up to 45°) continental slope supported by the growth of thick, massive calcareous reefs (e.g., Bahamas-Cuba, southwest Africa [Fairbridge, 1966]). 

Foissner, W., Agatha, S., Berger, H. (2002). Soil dilates (Protozoa, Ciliophora) from Namibia (Southwest Africa), with emphasis on two contrasting environments, the Etosha region and the Namib Desert. Denisia 5,1-1459. 

Ichaboe Island off the coast of Southwest Africa was the source of the first non-Peruvian guano by 1843, just three years after their discovery, these deposits (amounting to some 300,000 t) were stripped bare. Later non-Peruvian exports included shipments from Caribbean islands (Sombrero in the Leeward Islands, Na-vassa west of Haiti, tiny islands off Yucatan and Venezuela), as well as from Bolivia, Brazil, Australia, and the island of St. Helena in the South Atlantic. None of these deposits had as much nitrogen as the Chincha guanos. So-called rock or crust guanos... 

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