Paleobiodiversity and Tectono-Sedimentary Records in the Mediterranean Tethys and Related Eastern Areas pp 225-227 | Cite as
Carbonate Deposit Microfacies and Carbonatogenesis of Abiod Formation (Campanian/Maastrichtian) in Jebel Kebar (Central Tunisia)
Abstract
The present work aims to study the origin of limestones and carbonatogenesis of the Abiod Formation (Campanian Maastrichtian) in Jebel Kebar area (Central Tunisia). This work is based on the examination of a geological section in Jebel Kebar area. The polarizing microscopic observation of thin sections of limestone allowed us to determine four depositional facies: (i) Planctonic foraminifera-rich mudstone-wackestone, (ii) Calcisphera-rich mudstone, (iii) Bioclastic-bioturbated mudstone and (iv) Bioturbated mudstone, which is developed in turn in open circalittoral, circalittoral and infralittoral environments. These different carbonate facies correspond respectively to Transgressive and Regressive systems tracts that determine carbonate depositional sequences. The SEM observation shows that the Abiod Formation limestone is essentially micritic with three kinds of micrite (i) biodetrital micrite (ii) Chemical micrite (chemical precipitation) and (iii) Biological micrite (bacteria product?). The biodetrital micrite is the most represented in the studied limestones in comparison with the other kinds of micrite. The mineralogy, calcimetry, geochemical element concentrations and magnetic susceptibility (SM) show cyclic vertical changes which are related to the deposit facies (systems tracts) variation in the same way the maximum carbonate production rates are related to the transgressive intervals and mainly resulted from the biodetrital micrite accumulation. Accordingly, it seems that the carbonatogenesis was at least in part controlled by the sea-level fluctuation.
Keywords
Facies Carbonatogenesis Bacteria Campanian maastrichtian Jbel kebarReferences
- 1.Collin, P.Y., Loreau, J.P., Courville, P.: Depositional environments and iron ooid formation in condensed sections (Callovian-Oxfordian, south-eastern Paris basin, France): Sedimentology 52, 969–985 (2005)CrossRefGoogle Scholar
- 2.Touir, J., Zaghbib-Turki, D.: Effets des oscillations eustatiques couplées à une tectonique synsédimentaire sur la marge sud de la Téthys au Sénonien: exemple du Jebel M’rhila, Tunisie centrale. Creataceous Res 5, 675–695 (2004)CrossRefGoogle Scholar
- 3.Negra, M.H, F.: Upper cretaceous platform-derived conglomerates in Central Tunisia: significance and genesis mode. In: Gili, E., Negra, M.H., Skelton, P.W. (eds.) North African Cretaceous Carbonate Platform Systems. NATO Science Series, IV/28, pp. 129–141 (2003)CrossRefGoogle Scholar
- 4.Sushmitha, B., Baskar, R., Mauclaire, L., McKenzie, J.: Role of microbial community in stalactite formation, Sahastradhara caves, Dehradun. India. Curr. Sci. 88, 1305–1308 (2006)Google Scholar