Relationship between volcanism and marine sedimentation in northern Austral (Aisén) Basin, central Patagonia: Stratigraphic, U-Pb SHRIMP and paleontologic evidence

M. Suárez, R. De La Cruz, B. Aguirre-Urreta, M. Fanning

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The northernmost part of the oil-producing Austral Basin, known as Aisén Basin or Río Mayo Embayment (in central Patagonian Cordillera; 43-46°S), is a special area within the basin where the interplay between volcanism and the initial stages of its development can be established. Stratigraphic, paleontologic and five new U-Pb SHRIMP age determinations presented here indicate that the Aisén Basin was synchronous with the later phases of volcanism of the Ibáñez Formation for at least 11 m.yr. during the Tithonian to early Hauterivian. In this basin marine sedimentary rocks of the basal units of the Coihaique Group accumulated overlying and interfingering with the Ibáñez Formation, which represents the youngest episode of volcanism of a mainly Jurassic acid large igneous province (Chon Aike Province). Five new U-Pb SHRIMP magmatic ages ranging between 140.3 ± 1.0 and 136.1 ± 1.6 Ma (early Valanginian to early Hauterivian) were obtained from the Ibáñez Formation whilst ammonites from the overlying and interfingering Toqui Formation, the basal unit of the Coihaique Group, indicate Tithonian, early Berriasian and late Berriasian ages. The latter was a synvolcanic shallow marine facies accumulated in an intra-arc setting, subsequently developed into a retro-arc basin.

Original languageEnglish
Pages (from-to)309-325
Number of pages17
JournalJournal of South American Earth Sciences
Volume27
Issue number4
DOIs
Publication statusPublished - 1 Apr 2009

Keywords

  • Austral Basin
  • Gondwana
  • Late Jurassic-Early Cretaceous
  • Patagonia
  • SHRIMP geochronology
  • Transgression
  • Volcanism

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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