- Accueil
- Volume 99 (1976)
- Fascicule 1
- Découverte de quelques structures énigmatiques, probablement d'origine organique, dans un niveau stromatolithique de la Dipeta (Riphéen supérieur), près de Lubumbashi (Shaba, Zaïre)
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Découverte de quelques structures énigmatiques, probablement d'origine organique, dans un niveau stromatolithique de la Dipeta (Riphéen supérieur), près de Lubumbashi (Shaba, Zaïre)
Abstract
Discovery of some aberrant structures, probably of organic origin, in a stromatolitic level of upper Riphean age (Precambrian) near Lubumbashi (Shaba, Zaïre). In the Star Mine, situated at about 12 km East of Lubumbashi (Republic of Zaïre), a stromatolitic level belonging to the Dipeta Formation (see table I), more specially to Dp2, has been studied and in a series of petrological slides several aberrant structures have been observed. The embedding rock is a finely stratified dolomite, bearing iron oxides concentrations of various types, as filaments, amorphous fillings of cavities between crystals and very close accumulations. Those accumulations are rather variable in shape (see figures) and relatively large (0.100 — 0.300 mm). We assume an organic origin. Studies on relative and absolute geochronology, done by Cahen (1973, p. 46), establish an Upper Riphean age (between 1050 and 1000 m.y.) for the Dipeta Formation.