Thermal and hydrothermal influence of magmatic emissions on embedding clays of the Upper Cretaceous of the Tunisian eastern margin and the Pelagic Sea

During the Upper Cretaceous, magmatic manifestations took place in the Tunisian eastern margin and the Pelagic Sea. Intrusions are mainly microdolerites, whether they are accompanied or not by basaltic lava flows, breccia, pyroclastic facies. Thermal influence of the intrusions on the embedding sedimentary deposits resulted in a set of transformations. Temperature elevation and hydrothermal conditions led to the neoformation of chlorite and mixed-layered illite–chlorite near to the intrusions and below the lava flows. Illite crystallinity is improved close to the microdolerites and basaltic lava flows.