Genetic evolution of Permo-Triassic volcaniclastic sequences at Uspallata, Mendoza Precordillera, Argentina

STRAZZERE LEONARDO; GREGORI DANIEL A; DRISTAS JORGE

GONDWANA RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2006 vol. 9 p. 485 - 499

1342-937X

Permo-Triassic volcanic rocks of the Choiyoi Group crop out at Quebrada de Santa Elena and del Telégrafo, Mendoza Precordillera, Argentina. In this area, six volcanic events were generated through three volcanic stages that include collapse of voluminous Plinian columns associated to caldera pressurization and depressurization, emplacement of sub-volcanic bodies and dikes connected to depressurization of the magmatic chamber and establishment of resurgent domes and lava associated to caldera collapse events. Petrologic and geochemical data indicate increasing acidification toward younger events varying from dacitic to rhyodacitic and rhyolitic rocks. The lithofacial organization allows correlating with the Lower to Upper Permian Horcajo Formation described in the Valle del Río de los Patos, San Juan province. Geochemical data suggests subduction-related arc magmatism in an extensional condition during Lower to Upper Permian.