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Facies, stratigraphy and magnetic susceptibility of lower Cretaceous (Aptian-Albian) strata from Djebel Felten Formation, central rim of the Constantine shelf, NE Algeria
Laziz Ouided, Frédéric Boulvain, Chaouki Benabbas, Moussa Boularak

Building: Muséum d'Histoire Naturelle de Genève
Room: Lobby /Hall/
Date: 2018-12-05 12:24 PM – 12:27 PM
Last modified: 2018-11-30

Abstract


The sedimentological analysis of an Aptian-Albian carbonate succession, well dated by benthic and planktonic foraminifers, which crops out at Djebel Felten, has allowed the recognition of 25 lithofacies grouped into 12 microfacies associations that imply carbonate platform environments. The succession is repeatedly interrupted by emersions, suggesting high-frequency relative sea-level oscillations.

Stacking pattern of the limestone-marl alternations and facies evolution allow the identification of sequence boundaries, transgressive surfaces, and maximum-flooding events or condensed sections of at least two hierarchical levels.

The magnetic susceptibility (MS) signal appears to be influenced by facies and platform geometry. The evolution of MS seems to be mainly related to changes in carbonate productivity, water agitation and unconformities: algal facies and biomicrites (rudist floatstones) corresponding to high carbonate production show the lowest signal, whereas black pebbles, paleokarsts, and storm deposits are characterized by higher values. In addition, the MS signal from proximal microfacies have higher values than the distal ones. MS appears to be a useful complementary proxy for palaeoenvironmental interpretations, correlations and sequence stratigraphy. For instance, sea level rise led to a decrease in the content of the detrital materials, and therefore to a decrease in the susceptibility values. On the top of HST, the uplift and exposure events may lead to elevated magnetic susceptibility values. Carbonate susceptibilities can therefore be considered as one of the environmental proxy data for sequence stratigraphic investigation.