From the Andes and the Drake Passage to the Rio Grande Submarine Fan: Paleoclimatic and paleogeographic evidence in the Cenozoic Era from the South Atlantic – Austral Segment, Pelotas Basin

Abstract

The Cenozoic depositional history of the Pelotas Basin was driven by the interaction between the spreading processes of the Atlantic Ocean and the formation of the Andean Cordillera. We integrated seismic interpretation and backstripping techniques with evaluation of spreading rates in the South Atlantic and subduction beneath the Andes to unveil the main climatic, eustatic and active tectonic events in the Cenozoic. The achieved results integrated with regional geology and Cenozoic history data show the tectonic control that the Andean Cordillera exerted over the Pelotas Basin's passive margin. On the other hand, climatic and glacioeustatic changes that influenced the Pelotas Basin's sedimentation were mostly controlled by the tectonic opening of Drake Passage and the consequent onset of the Antarctic Circumpolar Current. These processes were directly connected to motions of the Antarctic, South American, and Nazca plates since the beginning of the Cenozoic. Our results allow us to detail the geological events of the Pelotas Basin and more accurately define its eustatic, tectonic, and climatic controls by closely observing the interaction between compressive tectonics and passive margins. • Drake Passage and Antarctic Circumpolar Current are recorded in the Pelotas Basin (PB). • Cenozoic glacioeustatic and tectonic events in the PB are connected to compressive and extensional margins. • Interaction between South American, Nazca, and Antarctic plates are crucial for South Atlantic Ocean sedimentation. • South Atlantic sea-floor spreading and Andean compressive tectonics control the sedimentation of the PB. • Rio Grande Submarine Fan shows Rio de la Plata contribution and contourites associated with ACC.