Seismic Imaging of Collapsed-Anticline Diapirs in Central Tunisia

Abstract

Central Tunisia is characterized by major fault systems, being ornamented by salt diapirs of the Late Triassic evaporite-rich interval. Salt movement began in the Late Triassic and continues to the present-day. Lasting halokinesis create pillows, diapirs, salt wall and salt-cored folds, sometimes, with collapse graben above. Salt diapir structures have been mapped and many regions collapsed diapirs are, perhaps, associated to salt removal. These structures were eroded resulting exposure and sub-aerial erosion by the Late Cretaceous to Paleogene uplift and post-Middle Miocene. The initial studies and findings related to salt structures in Tunisia suggesting a clear correlation between diapiric uplift and local tectonic structures. In particular, the N‒S and NW‒SE shortening trends during the Neogene and Quaternary folding strongly controlled the development of rows of diapirs and salt walls. The salt activities are controlled by tectonics as well as differential loading in the Triassic sediments over long distances, displaying that the mobilization of Triassic sediments covered the whole region and not just the zones near the single diapiric structures. Here we will focus also in the salt related plays and the associated petroleum systems with particular emphasis on trap types, reservoir and hydrocarbon migration pathways. Obviously, all these elements are linked together to certain degree and controlled by the salt tectonics.