Transition from the Cretaceous ocean to Cenozoic circulation in the western South Atlantic — A twofold reconstruction

摘要: Abstract The Cretaceous oceanic circulation has been quite different from the modern with a distribution of continents on globe. This resulted in much lower temperature gradient between poles and equator. We have studied seismic reflection data used numerical simulations atmosphere ocean dynamics to identify important steps modifications South Atlantic Cenozoic major factors controlling them. Starting Albian we could not any traces an overturning for although weak proto-Antarctic Circumpolar Current (ACC) was simulated. No change observed Paleocene/early Eocene Atlantic, which indicated that this period witnessed similar Cenomanian/Turonian circulation. most drastic were Eocene/Oligocene boundary Oligocene/early Miocene onset ACC meridional (AMOC) hence southern sourced deep bottom water masses western Atlantic. A AMOC, intensified strength after closure Central American Seaway (CAS), strong current controlled sedimentary features wide spread hiatusses since middle Miocene. opening Drake Passage early Oligocene times CAS at ~ 6 Ma, i.e., tectonic processes, identified as key triggers severe changes