EVOLUTION OF THE JURASSIC COMALLO VOLCANIC SEDIMENTARY COMPLEX IN THE WESTERN NORTH PATAGONIAN MASSIF, RIO NEGRO PROVINCE, ARGENTINA

BARROS, MERCEDES; GREGORI , DANIEL ALFREDO; BENEDINI, LEONARDO; MARCOS, PAULO; STRAZZERE, LEONARDO; PAVÓN PIVETTA, CECILIA

INTERNATIONAL GEOLOGY REVIEW

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2020 vol. xx

0020-6814

The Comallo volcanic sedimentary complex of the western North PatagonianMassif is composed of two members. The lower one includes massive andstratified lapilli tuffs, lithic and tuffaceous breccias, hyaloclastites, breccias, andcoherent andesite-dacites, and massive crystalline limestones. The upper memberconsists of red conglomerates, parallel and cross-stratification sandstones, andmudstones.The lower member is interpreted as having been deposited by dilute and densepyroclastic currents, block and ash deposits and lava-flow, and hypersalinelacustrine environments.The upper member is considered to have been deposited in fluviatileenvironments.The age is 192.0 ± 3.0 Ma (Sinemurian) and is coeval with several volcanicsedimentary units that crop out along the western North Patagonian Massif, theNeuquén basin and the Extraandean Chubut in pull-apart or rift depocenters. Themovements of the NW-SE strike-sleep faults that border the northern and southernlimits of the Comallo depocenter made possible the development of a pull-apartbasin and the volcanism and the fluvial system.This and other coeval units were deposited in similar environmental conditionsalong the North Patagonian Massif, the Neuquén basin and the extraandean Chubut, indicating a similar tectonomagmatic setting, in a tensional rear-arc during Lower Jurassic times.