Late Cenozoic basins and kinematics from the southernmost Andes in the context of the opening of the Drake Passage

GHIGLIONE, MATÍAS C.; CALDERÓN, M.; FOSDICK, J.; SUE, CHRISTIAN; STEVENS GODDARD, A.; VELEDA, M.; CUITIÑO, J.; GALLARDO, R.; SUÁREZ, R.; ARAMENDÍA, INÉS; ROJO, D.

Puerto Madryn

Congreso; Congreso Geológico Argentino XXI; 2022

Asociación Geológica Argentina

Mesozoic-Cenozoic interaction between South America and Antarctic plates has been a major driver of kinematics in the Southernmost Andes. Late Jurassic - Early Cretaceous opening of the Rocas Verdes oceanic basin was the product of separation, followed by Late Cretaceous basin closure and transpression along the Beagle channel due to left-lateral relative displacement. Orogen building continued during the Paleogene, together with progression of sedimentation in the associated Magallanes-Austral marine foreland basin system. The Eocene early opening of the Drake passage due to Antarctica separation, involved the combination of strike-slip and extensional tectonics, superposed to the previously consolidated orogen. Since the Oligocene inception of oceanic spreading in the West Scotia Sea, strike-slip deformation has dominated, concentrated along the Magallanes-Fagnano fault zone. As a result, Eocene and Miocene continental pull-apart basins are registered in a hinterland position. Coeval retroarc Miocene sedimentation includes an important continental volcaniclastic component and an important distributary system funneling sediments to deep marine basins. The position of the isolated Miocene basin along the Magallanes strait and on top of the fold-thrust belt, when compared to the retroarc sequences, open questions regarding the overall tectonic subsidence setting. For example, tectonic loading, dynamic subsidence, and transtension/pull-apart extension seems to be superposed; alternatively, they may be partitioned processes and geographically distributed. Furthermore, new detrital zircons provenance data from the retroarc, points out a Miocene reactivation of orogenic sources, coetaneous with pull-apart basins and widespread volcanism.