Abstract

Dr P. L. Binda writes: Annels (1984) suggests that the Zambian Copperbelt was the site of rifting during the deposition of at least part of the Katanga Sequence and that the mineral deposits are Red-Sea type.Intracratonic depositional settings may be fault-bounded or slowly subsiding basins, but rifting does not necessarily imply hydrothermal systems capable of brininging about mineralizations on the scale of the Zambian–Zaïrean Copperbelt.

Schneiderhöhn (1937) psroposed that copper was derived from the erosion of a mineralized hinterland and carried—partly as detritus, partly dissolved─to be deposited, syngenetically and diagenetically, in rocks of the Katanga Sequence. Pre-Katangan rocks in Zambia are rich in copper, and there is no difficulty in deriving enough copper from weathering of the basement to account for the Katangan deposits. Some of the Zambian deposits contain economic concentrations of cobalt, but data on cobalt in the basement are lacking. Annels proposes that cobalt and copper were derived from basic magmas at depth, and interprets the various bodies of amphibolite shown in his fig. 5 as high-level intrusives, and possibly submarine extrusives

Most of the Copperbelt amphibolites are probably metamorphosed gabbros, but there is no evidence that any are volcanic rocks. The only volcanics recorded in the Katanga Sequence in Zambia are in one drill hole (NE6B) in the Ndola area.

The spatial relationship between arnphibolites and cobalt distribution is not as clear as Annels suggests, and in his fig. 4 the Upper Roan cobalt occurrence of Mufulira is ignored. Furthermore, the Série des Mines

First Page Preview

First page PDF preview
You do not currently have access to this article.