Siliciclastic-Carbonate Stromatolite Domes, in the Early Carboniferous of The Ajjers Basin (Eastern Sahara, Algeria)

摘要: Stromatolite domes crop out widely in the upper Visean of eastern Sahara, Algeria and Lybia. Their growth was conditionned by sedimentary regime prevailing Sahara during Early Carboniferous times, as well specific features sedimentation over cratonic areas. The stromatolites two major units are discrete juxtaposed with high total relief. same kind laminae, probably built cocoid cyanobacteria bacteria, found all domes. Some them characterized a percentage siliciclastic material. Stromatolites grew very quiet subaqueous environments protected from open marine water. lower unit, strictly base to top sequence (except for an increase size). unit is typical shallowing-upward para-sequence, starting large passing stromatolite heads intertidal settings. In similar deposits Lybia, Whitbread Kelling (1982) interpreted “Collenia interval” resulting widespread delta abandonment. terms stratigraphy sequences containing High Stand System Tracts following sea level rise. However some differences observed indicate distinct conditions growth: have developed lakes fed fresh-water streams, while those second involved lagoon oolitic bars, filled sea-level rises progressively. extension thickness layers imply deposition large, flat, stable areas, low subsidence rate, characteristic feature West African Craton since Proterozoic.