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

Eduardo B. Olivero, Pablo J. Torres Carbonell, Martin Svojtka, Mark Fanning, Francisco Hervé, Daniel Nývlt

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

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.

Original languageEnglish
Article number102853
JournalJournal of South American Earth Sciences
Volume104
DOIs
Publication statusPublished - Dec 2020

Keywords

  • Austral-Magallanes basin
  • Detrital zircons
  • Eocene volcanism
  • FuegianAndes
  • U–Pb dating

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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