Compressional Tectonics Since Late Maastrichtian to Quaternary in Tunisian Atlas
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Some authors consider that compressional tectonic to have begun in late Cretaceous and continued until Quaternary in the Atlas Mountains of Tunisia. Others propose relaxation periods characterized by distensional tectonic regime. In this study, we made use of detailed geological mapping, fault-slip field data and seismic data from the southern and northern regions of Tunisia, in order to highlight the variation of paleostress during tectonic inversion. Three directions of principal compressive stress σ 1 are deduced from fault-slip data: NW-SE, NE-SW and N-S. The compressive tectonics induce different tectonic regimes: strike slip, compressional strike slip, extensional strike-slip and compressive during Late Maastrichtian-Quaternary period in the Tunisian Atlas. Fold-axes present different directions: E-W, N-S, NW-SE and NE-SW. In some localities, major faults juxtapose folds which makes their axes are perpendicular. This structural complexity and the change of stress axis can mainly be related to two factors: (1) variation of geometry and kinematics of African plate boundary which can generate several shortening directions (2) heterogeneity of sedimentary cover due to detachment layers and to pre-existent structures as fault and diapirs which contributes to reorient the stress direction.
KeywordsAtlas Tunisia Compressive regime Late Maastrichtian to quaternary Paleostress
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