Sur lʼâge et la genèse de certains gîtes metallifères dans lʼAtlas tunisien (dʼaprès les études isotopes du Pb)

Pages: 
pp. 51-64
Institut de Recherches gitologiques, 1505 Sofia
Institut de Recherches gitologiques, 1505 Sofia
lnstitut de Recherches nucléaires et d'énergie nucléaire, Acad. bul. des Sciences, 1784 Sofia
Abstract: 

B. Maneva, D. Manev, B. Amov. On the age and genesis of certain mineral deposirs in the Tunisian Arias (based on studies of Pb-isotopes). The radioisotopic studies carried out on mineralizations from the Tunisian Atlas allow to additionally elucidate the debatable question concerning their age and genesis. The data obtained for the isotopic composition of Pb fall between the curves of growing of "orogen" and "Upper Cretaceous" which indicates a crustal source of the metals. Besides the data obtained, they also indicate that the mineral-formation process occurred polychronously. These conclusions are in accordance with the phenomena caused by the conversion of the plates of the lithosphere at the boundaries of the Tunisian Atlas. During the thickening and reprocessing of the Earth's crust an additional supply of radiogenic lead into "Upper Cretaceous" was realized.
   Large masses of Triassic evaporitic sediments were mobilized during the multifold periods of tectonic activity. The Triassic diapirism favoured the generation, mobilization and draining of hydrothermal solutions which enriched in metals at the expense of their leaching by the adjacent rocks or by preceding mineralizations.
   The mineralization started first in the East Tunisian structural metallogenic zone along the N-S tectonic lineament. lt evolved from the end of Lower Cretaceous until Miocene tending to rejuvination from the central towards the external parts of the Tunisian Atlas.

VOLUME 21 (2)/April 1991

Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
|
Geological Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria

Institut de Recherches gitologiques, 1505 Sofia
|
Institut de Recherches gitologiques, 1505 Sofia
|
lnstitut de Recherches nucléaires et d'énergie nucléaire, Acad. bul. des Sciences, 1784 Sofia

Geological Institute, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria