Cenozoic intraplate magmatism of central Patagonia, Argentina

HALLER, MIGUEL J.; MASSAFERRO, GABRIELA I.; ALRIC, VIVIANA I.; NAVARRETE, CÉSAR R.; MENEGATTI, NILDA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 102

0895-9811

During Cenozoic times, Patagonia was characterized by an intense magmatic intraplate activity that gave rise toa large volume of basaltic flows and intrusive bodies. This work aims to gather all the available informationalong with unpublished data of the authors about this magmatism that crops out in the center and south of theChubut Province, Patagonia Argentina.Small outcrops of Paleocene basalts are present northeast of Paso de Indios and east of Colhué Huapi Lake.The Eocene rocks are represented by basalt flows and intrusive bodies distributed in the west-center, center, andsouth-west of the Chubut Province. The most significant volume of rocks was produced during the upperOligocene-lower Miocene generating Meseta Canquel, Sierra Nevada, Sierra De Buen Pasto, and Meseta LosGalpones. Many intrusive gabbroic bodies with different geometries, related to this extended volcanism, crop outin the surroundings of the Colhué Huapi and Musters lakes. The basaltic volcanism of the upper Miocene isrepresented mainly in the northwest of the Chubut Province. The Pliocene basalts are distributed in the SanBernardo fold and thrust belt. The Pleistocene basalts form volcanic fields of reduced extensions in the north ofChubut, west of Gastre; in the center, near Pampa de Agnia; in the southwest, in the valley of Genoa River andthey also form isolated scoria cones located atop Meseta Canquel.Most of the studied rocks have alkaline affinities and OIB signatures, typical of magmas related to garnetiferous peridotite sources.The origin of this basic Paleogene-Pleistocene magmatism, although there are several proposals, would belinked to regional geodynamic processes that include the subduction of mid-ocean ridges with the generation ofslab asthenospheric windows and, lithospheric extensional periods related to the steepening of the subductedoceanic lithosphere, as well as a possible relationship with a stagnant oceanic slab at depths of the transitionmantle