Eocene volcanism in the Fuegian Andes: Evidence from petrography and detrital zircons in marine volcaniclastic sandstones

• Published in: Journal of South American Earth Sciences
• Main Authors: Olivero, Eduardo Bernardo, Torres Carbonell, Pablo Juan, Svojtka, Martin, Fanning, Christopher Mark, Hervé, Francisco, Nývlt, Daniel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd
• Subjects: AUSTRAL-MAGALLANES BASIN; DETRITAL ZIRCONS; EOCENE VOLCANISM; FUEGIANANDES; U–PB DATING; https://purl.org/becyt/ford/1.5; https://purl.org/becyt/ford/1; Austral; Argentino; Argentina; Magallanes; Pablo; Fanning; Bello; Carbonell; Olivero; Antártida; Tierra del Fuego
• Online Access: http://hdl.handle.net/11336/126806

The sedimentology, petrography, and U–Pb dating of two Eocene volcaniclastic horizons of the Punta Torcida and Leticia formations, Austral basin, Tierra del Fuego, Argentina are interpreted and documented. The volcaniclastic deposits, pumicite breccia and tuffaceous sandstones, are formed by glass shards, plagioclase crystals, and pumiceous and lithic andesitic fragments. Originally deposited as tephra fallout, they have been subsequently reworked and redeposited in marine settings. The final deposits, however, are interpreted essentially as syn-eruptive. U–Pb dating of detrital zircons gave a 46.3 ± 0.4 Ma (early Lutetian) age for the top of the Punta Torcida Formation and 41.9 ± 0.71 (late Lutetian) to 39.6 ± 0.82 (Bartonian) ages for the Leticia Formation. Paleogene volcanic rocks are unknown in the Southern Patagonian-Fuegian Andes; hence the studied volcanic deposits with minimal reworking are important to evaluate the time lag between eruption and true depositional ages in detrital zircons. The resulting dates allow evaluating the timing of the important, basin-wide, intra-Eocene unconformity known from Tierra del Fuego to Lago Argentino, Santa Cruz, Argentina. The documented eruptive phases are related to Andean magmatism, probably located in the outcrop area of the Seno Año Nuevo suite in the Chilean Archipelago. Fil: Olivero, Eduardo Bernardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentina Fil: Torres Carbonell, Pablo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Svojtka, Martin. Institute Of Geology; República Checa Fil: Fanning, Christopher Mark. Australian National University; Australia Fil: Hervé, Francisco. Universidad Andrés Bello; Chile. Universidad de Chile; Chile Fil: Nývlt, ...