Cretaceous palaeoceanographic events of the northern South Atlantic: an overview

Abstract

Abstract The break-up of Gondwana in the latest Jurassic and earliest Cretaceous and the subsequent opening and evolution of the South Atlantic Ocean as a new widening seaway linking northern and southern high latitudes, was the single most significant palaeoceanographic event during the Cretaceous with global consequences for the climate and the biotic evolution, both on land and at sea. Its main evolutionary stages are now becoming well known but, despite that, their global impact has been widely underestimated. Aiming to shed light on some of these unanswered questions, this work presents an overview of research carried out during the past decades in the Sergipe Basin in northeastern Brazil, integrating foraminiferal and ammonite biostratigraphic data, coupled with an assessment of their biogeographic patterns. Three main topics are discussed, and the key findings presented and set against their possible global impact: the opening of the Equatorial Atlantic Gateway in the late early to mid Aptian ( c. 118–119 Ma); the mid-Cretaceous dysoxic–anoxic events recorded in the northern South Atlantic (maxima in the late Aptian–earliest Albian, early Cenomanian and at the Cenomanian–Turonian boundary); and the timing of the North Atlantic–South Atlantic oceanic connection in the late Coniacian to early Santonian ( c. 85–87 Ma).