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Stratigraphy and morphotectonics of Karoo deposits of the northern Selous Basin, Tanzania

Published online by Cambridge University Press:  01 May 2009

H. Wopfner  and
C. Z. Kaaya
H. Wopfner
Affiliation:
Geologisches Institut, Universität zu Köln, Zülpicherstr. 49. D 5000 Köln 1, Germany
C. Z. Kaaya
Affiliation:
Geology Department, University of Dar es Salaam, P.O. Box 35052, Dar es Salaam, Tanzania
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Abstract

Late Permian Karoo deposits of the northern Selous Basin in south-central Tanzania comprise conglomerates and diamictitic boulder beds of alluvial and scarp-foot fan origin. These merge with grey to greenish sandstones, siltstones and black shales of deltaic and lacustrine environments. Microflora assemblages indicate a late Permian age. Lateral changes and interfingering of various lithofacies units are common. Depositional development was controlled by syndepositional faulting and variations of gradients resulting from fault movements. The position of the fault scarp separating the basin area from the elevated basement horst to the west roughly corresponded with the present boundary between the Selous Basin and the Precambrian metamorphics of the Uluguru Mountains.

The late Permian Karoo succession of this part of the Selous Basin apparently overlaps older Karoo deposits contained in the north-northeast trending narrow graben structures. It is therefore regarded as a new depositional event which was initiated by renewed tensional tectonism in late Permian time. During this tectonic episode the narrow early Karoo graben structures were expanded into much broader rift basins. Material eroded from the rift shoulders and associated highlands was literally dumped across the fault scarps, forming debris aprons and scarp-foot fans. Rivers emanating from the highlands formed large alluvial fans and, further afield, deltas issued into freshwater lakes.

Some of these late Permian faults were rejuvenated by late Cretaceous to early Tertiary tectonism. Thermal waters circulating along fractures converted feldspars, biotites and hornblendes to prehnite. Further tectonic adjustments in mid Tertiary time led to the present-day morphology.

Type
Articles
Information
Geological Magazine , Volume 128 , Issue 4 , July 1991 , pp. 319 - 334
Copyright
Copyright © Cambridge University Press 1991

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References

Allen, J. R. L. 1970. Sediments of modern Niger Delta: a Summary and Review. Society of Economic Paleontologists and Mineralogists, Special Publications no. 15, 138–51.Google Scholar
Batterham, P. M., Bullock, S. J. & Hopgood, D. N. 1983. Tanzania: integrated interpretation of aero-magnetic and radiometric maps for mineral exploration. Transactions, Institute of Mining and Metallurgy, London, Section B 92, 83–92.Google Scholar
Bornhardt, W. 1900. Zur Oberflächengestaltung und Geologic Deutsch-Ostafrikas, 7, Berlin: Dietrich Reimer, 595 pp.Google Scholar
Coleman, J. M. & Gagliano, S. M. 1970. Sedimentary structures: Mississippi river deltaic plain. In: Primary sedimentary structures and their hydrodynamic interpretation (ed. Middleton, G. V.), pp. 133–48. Society of Economic Paleontologists & Mineralogists, Special Publication no. 12.Google Scholar
Coleman, J. M. & Prior, D. B. 1982. Deltaic environments of deposition. American Association of Petroleum Geologists, Memoir 31, 139–78.Google Scholar
Falvey, D. A. 1974. The development of continental margins in plate tectonic theory. Australian Petroleum Exploration Association Journal 14 (1), 95–106.Google Scholar
Fisk, H. N. 1961. Bar-finger sands of the Mississippi Delta. In: Geometry of sandstone bodies (eds Peterson, J. A. and Osmond, J.C.), pp. 25–52. Tulsa: American Association of Petroleum Geologists.Google Scholar
Fouch, T. D. & Dean, W. E. 1982. Lacustrine and associated clastic depositional environments. American Association of Petroleum Geologists, Memoir 31, 87–114.Google Scholar
Haldemann, E. G. 1962. The geology of the Rufiji Basin with reference to proposed dam sites. Geological Survey of Tanganyika Bulletin no. 33, 77 pp.Google Scholar
Hankel, O. 1987. Lithostratigraphic subdivision of the Karoo rocks of the Luwegu Basin, Tanzania and their biostratigraphic classification based on microflora, fossil wood and vertebrates. Geologische Rundschau 76 (2), 539–66.CrossRefGoogle Scholar
Hankel, O. 1990. Lower Triassic spores and pollen from a borehole in the lower Mariakani Formation (Karoo) of Kenya. Berliner geowissenschaftliche Abhandlungen (A) 120, (2), 639–78.Google Scholar
Janensch, W. 1927. Beitrag zur Kenntnis der Karru-Schichten im östlichen Deutsch-Ostafrika. In: Wissen-schaftliche Ergebnisse der Tendaguru-Expedition, 1909–1912. Palaeontographica, N. F., Supplementum 7, 107–42.Google Scholar
Kent, P. E., Hunt, J. A. & Johnstone, D. W. 1971. The geology and geophysics of coastal Tanzania. Geophysical paper No. 6. London: H.M.S.O., 101 pp.Google Scholar
Kögler, K., Bianconi, F. & Büttner, W. 1983. Geo-chemical behaviour of uranium in lateritic profiles in southern Tanzania. In: Uranium exploration in wet tropical environments, pp. 119–35. Vienna: International Atomic Energy Agency.Google Scholar
Kreuser, T. 1983. Stratigraphie der Karroo-Becken in Ost-Tanzania. Geologisches Institut, Universität Köln, Sonderveröffentlichung 45, 217 pp.Google Scholar
Kreuser, T., Wopfner, H., Kaaya, C. Z., Markwort, S., Semkiwa, P. M., & Aslanidis, P. 1990. Depositional evolution of Permo-Triassic Karoo Basins in Tanzania with reference to their economic potential. Journal of African Earth Sciences 10 (1/2), 151–67.CrossRefGoogle Scholar
Liou, J. G. 1971. Synthesis and stability relations of Prehnite. American Mineralogist 56, 507–31.Google Scholar
Nilsen, T. H. 1982. Alluvial fan deposits. American Association of Petroleum Geologists, Memoir 31, 49–86.Google Scholar
Petracca, A. N. 1986. Oil and gas developments in central and southern Africa in 1985. American Association of Petroleum Geologists Bulletin 70 (10), 1412–57.Google Scholar
Sampson, D. N. 1958. The Uluguru Mountains (A summary of the progress to 1955). Records of the Geological Survey of Tanganyika 5, 21–35.Google Scholar
Spence, J. 1955. Geological Map, 1:125000. Quarter Degree Sheet 64 SE, Mkalinzo. Geological Survey of Tanganyika, G.S. 911.Google Scholar
Spence, J. 1957. The geology of the eastern province of Tanganyika. Geological Survey of Tanganyika Bulletin 28, 62 pp.Google Scholar
Stockley, G. M. 1936. A further contribution on the Karoo rocks of Tanganyika Territory. Quarterly Journal of the Geological Society of London 92, 1–31.CrossRefGoogle Scholar
Veevers, J.J. 1989. Middle/Late Triassic (230±5 Ma) singularity in the stratigraphic and magmatic history of Pangean heat anomaly. Geology 17, 784–7.2.3.CO;2>CrossRefGoogle Scholar
Wopfner, H. 1972. Depositional history and tectonics of South Australian sedimentary basins. In: Proceedings 4th Symposium, Development of Petroleum Resources of Asia and the Far East 1 (2), 251–67. ECAFE Mineral Resources Development Series 41, lUnited Nations, New York.Google Scholar
Wopfner, H. in press, a. Permo-Triassic sedimentary basins in Australia and East Africa and their relationship to Gondwanic stress pattern. Proceedings 7th Gondwana Congress, Sao Paulo, Brazil, 1988.Google Scholar
Wopfner, H. in press, b. Rifting in Tanzanian Karoo basins and its economic implications. 15th Colloquium on African Geology, Nancy, 1990. Extended Abstracts, CIFEG, Service Documentations & Editions, Orleans.Google Scholar