Abstract
The chemical composition of common rock types of the Damara Secquence has been investigated. About 300 well selected samples were analysed. The influence of recent weathering on the composition of the collected samples is small. Under the prevailing conditions mechanical decomposition of the rocks is much more important than any chemical process.
The processes of decomposition and transportation of the Pre-Damara rocks forming the sediments of the Damara geosyncline, can be traced by the trends of chemical composition in the common rock types. As sodium depleted pelitic rocks as well as pure quartzitic rocks are uncommon in the investigated sequences, repeated cycles of reworking of sediments in the geosynclinal state can be excluded.
Increasing metamorphism of the Damara rocks resulted in an increasing FeO/Fe2O3 ratio but constant total iron content; decreasing CO2 content and decreasing H2O content. Loss of sodium and potassium can be exluded. Some 4 % of carbonate detritus seems to be a maximum value for the sedimentation of average Damara pelitic rocks.
Rifting was the governing tectonic process in the evolution of the Damara. It is characterized by short transportation distances and high vertical subsidences — both favouring single step sedimentation processes — the prerequisite of sediment compositions found for the main rock types of the Damara Sequence.
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References
Eade, K.E., Fahrig, W.F (1971) Geochemical evolutionary trends of continental plates-a preliminary study of the Canadian Shield.–Geol. Surv. Canada Bull. 179, 1–51.
Faupel, J. (1974) Geologisch-mineralogische Untersuchungen am Donkerhoek-Granit (Karibib-District, Südwest-Afrika).–Göttinger Arb. Geol. Paläont. 15, 1–95.
Hoffer, E. (1975) Die zeitliche Beziehung zwischen Tektogenese und Metamorphose: Ein Beitrag zur Rekonstruktion der thermischen Geschichte des Damara-Orogens.–Bericht des SFB 48, Göttingen, 170–183.
Hoffer, E. (1977) Petrologische Untersuchungen zur Regionalmetamorphose Al-reicher Metapelite im südlichen Damara-Orogen (Südwest-Afrika).-Habilitationsschrift, Göttingen.
Hoffer, E. (1982) Compositional variations of minerals in metapelites involved in low-to medium grade isograd reactions in the southern Damara Orogen, South West Africa/Namibia.–This vol.
Hoffmann, C. (1977a) Granites and migmatites of the Damara Belt, South West Africa. Petrography and melting experiments.–Geol. Rundschau 65, 939–966.
Hoffmann, C. (1977b) Granite intruding into granodiorite: An example from the Damara-Belt, South West Africa.–Geol. Rundschau 66, 465–477.
Germantzidis, C. (1980) Experimentelle Anatexis von häufigen Metasedimenten aus dem Damara-Orogen (Südwest-Afrika).–Dissertation, Göttingen.
Pettijohn, F.J. (1963) Chemical composition of sandstones –excluding carbonate and volcanic sands.–Geol. Survey Prof. Paper 440-S, 1–21.
Porada, H. (1982) Geodynamic model for the geosynclinal development of the Damara Orogen, Namibia/South West Africa.–This vol.
Puhan, D. (1982) Metamorphism of siliceous dolomites of the central and southern part of the Damara Orogen.–This vol.
Ronov, A.B. (1972) Composition evolution in rocks and geochemical processes in the sedimentary shell of the earth.–Trans. from Geokhimiya, No. 2, 137–147.
Ronov, A.B., Migdisov, A.A. (1970) Evolution of the chemical composition of the rocks in the shields and sediment cover of the Russian and North American Platforms.–Geochem. Internat. 7, 294–325.
Ronov, A.B., Girin, Yu.P., Kazakov, G.A., Ilyukhin, M.N. (1966) Sedimentary differentiation in platform and geosynclinal basins.–Geochem. Internat. 3, 595–608.
Ronov, A.B., Migdisov, A.A. (1971) Geochemical history of the crystalline basement and the sedimentary cover of the Russian and North American Platforms.–Sedimentology 16, 137–185.
Ronov, A.B., Girin, Yu.P., Kazakov, G.A., Ilyukhin, M.N. (1965) Comparative geochemistry of geosynclinal and platform sedimentary rocks.–Trans, from Geokhimiya, No. 8, 961–976.
Ronov, A.B., Yaroshevskiy, A.A. (1967) Chemical structure of the earth’s crust.–Geochem. Internat. 5, 1041–1066.
Ronov, A.B., Migdisov, A.A., Barskaya, N.V. (1969) Tectonic cycles and regularities in the development of sedimentary rocks and paleogeographic environments of sedimentation of the Russian Platform (an approach to a quantitative study).–Sedimentology 13, 179–212.
Ronov, A.B. (1972) Evolution of rock composition and geochemical processes in the sedimentary shell of the earth.–Sedimentology 19, 157–172.
Schmidt, A. (1982) Geochemische Untersuchungen an Graniten des Damara-Orogens/Namibia.–Dissertation, Göttingen.
Schulz-Dobrick, B. (1975) Chemischer Stoffbestand variskischer Geosynklinalablagerungen im Rhenoherzynikum.–Dissertation, Göttingen.
Schulz-Dobrick, B. (1979) Verteilung von Cd, T1 und Bi in Sedimentgesteinen.–Fortschr. Miner. 57, Beih. 1, 222–223.
Wedepohl, K.H. (1969) Composition and abundance of common sedimentary rocks.–Chapter 8 in: Wedepohl, K.H. (ex.ed.): Handbook of Geochemistry Vol. I, Springer-Verlag Berlin, Heidelberg, New York.
Wedepohl, K.H., Schulz-Dobrick, B. (1982) The chemical composition of sedimentary deposits in the Rhenohercynican Belt of Central Europe.–This vol
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Schneider, A. (1983). The Chemical Composition of the Common Metamorphic Sediments of the Damara Orogen. In: Martin, H., Eder, F.W. (eds) Intracontinental Fold Belts. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-69124-9_26
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DOI: https://doi.org/10.1007/978-3-642-69124-9_26
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