Field trip guide: Ridge-trench collision - The southern Patagonian Cordillera east of the Chile Triple Junction

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The southern Patagonian Cordillera south of the present location of the Chile Triple Junction (46.5°S) preserves distinctive deformational and backarc magmatic features that are a consequence of a series of northward-propagating ridge collision events that started at ca. 14 Ma. An abrupt increase of ∼2000 m of topographic elevation and the exhumation and uplift of mid-Miocene to Pliocene plutons within the cordillera south of the Chile Triple Junction is accomplished by horizontal compressive deformation (both thin- and thick-skinned) within the Patagonian fold-thrust belt. Ridge-trench collisions have formed asthenospheric slab windows beneath the southern Patagonian Cordillera. Backarc magmatism associated with slab window formation includes a distinctive suite of adakites and extensive outpourings of oceanic island basalt (OIB)-like plateau basalts. The adakites formed from the partial melting of the young, hot trailing edge of the Nazca plate that preceded slab window opening, whereas the OIB-like plateau basalts formed from dynamic asthenospheric flow as the slab windows opened up beneath the backarc.

Original languageEnglish
Title of host publicationGSA Field Guides
PublisherGeological Society of America
Number of pages22
StatePublished - 1 Jan 2008

Publication series

NameGSA Field Guides



  • Chile Triple Junction
  • Patagonia
  • Ridge-trench collision
  • Slab window
  • Southern Andes

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