0000000000724996
AUTHOR
Gonzalo Ronda
Tectonic evolution of the northern Austral-Magallanes basin in the Southern Patagonian Andes from provenance analysis
We studied the northern tip of the Austral-Magallanes basin in the Southern Patagonian Andes, between the Buenos Aires Lake and the Mayer River at 46°35′ SL and 48°35′ SL, respectively. Proposed objectives were: i) to differentiate Mesozoic-Cenozoic tectonostratigraphic units and, ii) to characterize the different deformational events that took place in the area linked to a variable regional geodynamic context. Sandstones provenance analysis was performed on the Aptian - Albian compressive retroarc deposits and Cenozoic foreland deposits. Studied samples were classified using tectonic discrimination diagrams which show: i) for Cretaceous rocks a dominant sediment source from a recycled orog…
Late Cenozoic brittle deformation in the Southern Patagonian Andes: Record of plate coupling/decoupling during variable subduction?
The Andes of southern Patagonia experienced a Miocene shift towards faster and higher angle subduction followed by the approach and collision of the Chile oceanic ridge. We present a kinematic study characterizing palaeostress fields computed from brittle tectonics to better constrain upper crustal deformation during this complex scenario. Although previous studies already suggested variable kinematics, it is striking that in a long-lasting subduction environment, the computed palaeostress tensors are mostly strike-slip (55%), while 35% are extensional, and only 10% compressive which are concentrated along a main frontal thrust. Cross-cutting relationships and synsedimentary deformation ind…