The Vembo Shales (Republic of the Congo): new insights on the transition from lacustrine to marine settings in the South Atlantic

Abstract : The Vembo Shales, originally defined in Gabon, are also recorded in Congo where they are recognized as the “terme argilo-carbonaté”[1]. This member of the Chéla Formation (Aptian), deposited just below the evaporites of the Loémé Formation, was recently identified in outcrops located 70 km to the NE of Pointe-Noire (Fig. 1) along the National Road 1 (RN1). These outcrops were not stratigraphically well-constrained due to the lack of fauna and were previously attributed [2] to undifferentiated Cretaceous (Fig.1) based on facies characteristics that are similar to succession exposed in outcrops in Gabon.