Szczegóły publikacji
Opis bibliograficzny
Revision of the stratigraphical position of the `Roches Argilo-Talqueuses' (R. A. T.) in the Neoproterozoic Katangan Belt, south Congo / Marek Wendorff // Journal of African Earth Sciences ; ISSN 1464-343X . — Błędny ISSN 0899-5362. — 2000 — vol. 30 iss. 3, s. 717–726. — Bibliogr. s. 726, Abstr., Rés. — Publikacja dostępna online od: 2000-07-18. — M. Wendorff - afiliacja: University of Botswana, Gaborone, Botswana. — Conference for the 50th Anniversary of the Geological Survey of Botswana : Botswana, 1998
Autor
- Wendorff Marek
Dane bibliometryczne
| ID BaDAP | 53095 |
|---|---|
| Data dodania do BaDAP | 2010-09-03 |
| Tekst źródłowy | URL |
| DOI | 10.1016/S0899-5362(00)00048-8 |
| Rok publikacji | 2000 |
| Typ publikacji | referat w czasopiśmie |
| Otwarty dostęp |  |
| Czasopismo/seria | Journal of African Earth Sciences |
Abstract
The outer sector of the Neoproterozoic Katangan Orogen of Central Africa is characterised by nappes thrust northwards, toward the foreland region, the major part of which occurs in the Democratic Republic of Congo (DRC). The rocks called R.A.T. ('Roches Argilo-Talqueuses') are terrigenous clastics traditionally considered as the oldest stratigraphical interval of these allochthonous units. They are correlated with the terrigenous elastic sediments at the base of the autochthonous Katangan succession in Zambia to the south, which were deposited at the opening stage of the Katangan Rift Basin. The lower interval of the R.A.T. represents red beds, whereas the upper one was deposited in anoxic conditions. Therefore, they are called red and grey R.A.T., respectively. This paper presents stratigraphic, structural and geochemical arguments against the traditional stratigraphical view and demonstrates that the R.A.T. rocks are younger than previously considered. They are interpreted here as synorogenic sediments of the Katangan foreland basin. Olistostromes with R.A.T. olistoliths, which occur either interbedded within 'normal' R.A.T. sediments or overlie angular unconformities, testify to pronounced tectonic movements and palaeotopography of the basin in which the R.A.T. sediments were deposited. The provenance of other olistoliths implies that, contrary to the previous views, the R.A.T. olistostromes are younger than the overlying rock complexes and the contact between the two is tectonic. Clastic dykes of the incompetent R.A.T. lithologies injected into the overlying competent units suggest that the former were partly unconsolidated sediments over-ridden by the Katangan nappes. Plots of the geochemical compositions point to two distinct tectonosedimentary cycles and two types of sources, each related to a different stage of orogen evolution. The terrigenous materials of the Katangan autochthonous strata (Roan and Kundelungu Groups) and correlative allochthonous units are derived from basement granitic and metamorphic rocks eroded during the opening of the Katagan rift basin. By contrast, the R.A.T. rocks are related to the closure of the basin. Their provenance is from the orogenic source-the Katangan nappes advancing towards the foreland region in the north. The autochthonous Roan Group rocks in Zambia and their allochthonous correlatives in DRC contain one of the richest Cu-Co deposits known. In accord with the previous correlation, the Cu-Co mineralisation in the grey R.A.T, rocks was considered of the same age as the Zambian deposits. However, the results presented in this paper imply that the grey R.A.T. deposits represent a second generation of mineralisation in the Katangan belt, younger than the Roan Group orebodies. The R.A.T. Cu-Co mineralisation is related to the anoxic stage of the foreland basin, and the advancing nappes containing Roan-correlative orebodies acted as the sources of the metals. In conclusion, points pertaining to the revision of stratigraphical classification of the Katangan Supergroup are proposed. (C) 2000 Elsevier Science Limited. All rights reserved.
