Campanian-Eocene dinoflagellate cyst biostratigraphy in the Southern Andean foreland basin: Implications for Drake Passage throughflow

The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for Cenozoic development Antarctic Circumpolar Current (ACC). Particularly complexity has hampered exact dating deepening phases, consequential onset throughflow ACC. One obstacles is putting key regional events, recorded in southern Patagonian sediments, absolute time. For that purpose, we have collected Campanian-Eocene sediment samples from Chilean sector Southern Patagonia. Using U-Pb radiometric on zircons dinoflagellate cyst biostratigraphy, updated age constraints sedimentary formations, hiatuses between. Thick packages shallow-marine continental sediments were deposited foreland basin during early Campanian, mid-Paleocene, Paleocene-Eocene boundary interval middle Eocene, which represent phases increased subsidence. We interpret spanning late early-to mid-Eocene latest Eocene-early Oligocene to indicate times reduced subsidence, relative supply. relate these changes varying subduction rates Andean orogeny. Dinoflagellate assemblages suggest region was under influence Antarctic-derived waters through western current Subpolar Gyre, developed southwest Atlantic Ocean thus argues limited until at least Eocene. However, proliferation endemism record coeval with Pacific, a species level, are same two regions. This suggests both regions oceanographically connected throughout Paleogene, likely shallow restricted Passage. implies continuous surface-water connection between south Pacific South Cretaceous-early Paleogene.