The Puesto Piris Formation: Evidence of basin-development in the North Patagonian Massif during crustal extension associated with Gondwana breakup

STRAZZERE, LEONARDO; DANIEL A. GREGORI; LEONARDO BENEDINI; PAULO MARCOS; MERCEDES BARROS; MAURO GERALDES

Geoscience Frontiers

Elsevier

Lugar: Beijing; Año: 2019 vol. 10 p. 299 - 314

1674-9871

Lower Jurassic sedimentary and epiclastic deposits exposed in the northeast North Patagonian Massif, Río Negro province, and assigned to Puesto Piris Formatión, has been studied in order to determine the sedimentary paleoenvironments and provenance. This unit includes an epiclastic sedimentary succession of about ~ 600 m thick, consisting of conglometates, sandstones, shales and mudstones, whith abundant tuff content. The unit includes alluvial fan systems dominated in proximal areas by hyperconcentrated and concentrated flows. Low-energy channelized flows and playa lake systems are interbedded with high-energy environments. The first includes epiclastic tuff, sandstone and limestones. The composition of the sedimentary and volcaniclastic deposits suggest different sources areas including low-grade metamorphic rocks, granites and volcanics fragment of the Marifil Volcanic Complex. An U-Pb age of 193.4 ±3.1 Ma obtained in a trachytic lava-flow underneath the conglomerates of Puesto Piris Formation suggests that the Puesto Piris Formation is coeval with the lower part of the Marifil Volcanic Complex. The main depocenter of the basin is elondated in a NE-SW direction associated with NW-SE extensional field related to a general context of crustal extension associated with Gondwana breakup event.