New evidence for Hercynian faulting in the southernmost margin of the Rharb Basin (Morocco)

Abstract The Miocene-Pliocene Rharb Basin has important groundwater and hydrocarbon potential in western Morocco. The Pliocene-Quaternary reservoir rests upon the Miocene-Pliocene marly units. The paleogeographic limits are based on planktonic foraminifera biozones. They contributed to the geometric reconstruction of this basin. The goal of the present study is to establish the paleogeographic evolution of the Rharb Basin and the Hercynian structures deduced from seismic and gravity data interpretation. The Pliocene-Quaternary deposits exhibit thickness and lateral facies variations. The Pliocene bathyal gulf showed several tectonic phases, marked by the westward migration of the paleogeographic limit in its eastern part, and a southward migration from its northern one. During Miocene-Pliocene times, the tectonic activity within the study area is characterized by extensional and compressional structures. The faults affecting the Paleozoic units were reactivated several times. The comparison between the paleogeographic limits and identified Hercynian structures constitutes fresh evidence for reactivation of pre-existing Hercynian faults