EXPRESSION OF OAE-2 IN THE WEST AFRICAN BENUE TROUGH

Organic carbon-rich shales deposited under anoxic conditions have been found globally during the Oceanic Anoxic Event 2 (OAE 2) at the Cenomanian – Turonian boundary (~93.5 Ma). The anoxia has been postulated to have been triggered by eruption of submarine Large Igneous Province. Although, OAE 2 occurrence has been global, local structural and paleogeographic variations have strong impact on the evolution of anoxia across the globe. Here, we present data from a new site from the west African Upper Benue Trough, a cretaceous rift basin that formed from the separation of Africa and South America during the Mesozoic and was part of a transcontinental seaway that connected the Atlantic Ocean to the paleo Tethys during the Cenomanian marine transgression. The OAE 2 deposits within the Benue trough is a 3 m black shales interval of the Pindiga Formation. Carbon isotope analysis shows a 3‰ δ¹³C positive excursion characteristic of the OAE 2 interval and conclusively showing for the first-time evidence of OAE 2 interval within the basin. We also measured trace and redox sensitive elements to further understand the development of anoxia within the Benue Trough.