U-PB geochronology and magnetostratigraphy of a north Patagonian syn-orogenic Miocene succession: Tectono-stratigraphic implications for the foreland system configuration

Joaquín Bucher, Florencia N. Milanese, Manuel López, Micaela García, Leandro D'Elia, Andrés Bilmes, Maximiliano Naipauer, Ana María Sato, Daniela Funes, Augusto Rapalini, Víctor A. Valencia, Roberto Ventura Santos, Natalia Hauser, Lucieth Cruz Vieira, Juan Franzese
Tectonophysics, Volume 766, 5 September 2019, Pages 81-93
The syn-orogenic Miocene deposits of the Patagonian Foreland System were the focus of numerous works in the latest years, due to their central role in the comprehension of the tectono-stratigraphy and tectonic evolution related to the Patagonian Andean growth. In this work we present a chronostratigraphic scheme based on magnetostratigraphy and UPb geochronology for one of the syn-orogenic successions of the Patagonian Foreland System: the Paso del Sapo Basin. The sequence is constrained to an age of >14.9 to <11.6 Ma, establishing ages of >14.9–14.6 Ma for the basal alluvial systems of La Pava Formation, with mean sedimentation rates of 4.2 cm/kyr; of 14.6 to 12.8–12.7 Ma for the lacustrine - deltaic environments of the lower Collón Cura Formation, with sedimentation rates ranging from 1.6 to 26.0 cm/kyr; and of 12.8–12.7 to <11.6 Ma for the alluvial systems of the upper Collón Cura Formation, with mean sedimentation rates of 8.5 cm/kyr. Our results indicate a continuous contractional tectonic phase at least during this time span (>14.9 to <11.6 Ma), which implicates that the Patagonian Foreland System at these latitudes was synchronously deformed with the tectonic activity along the Andean region.