Regional mid-Pleistocene glaciation in central Patagonia

Andrew Hein, Antoine Cogez, Christopher Darvill, Monika Mendelova, Michael Kaplan, Frédéric Herman, Tibor Dunai, Kevin Norton, Sheng Xu, Marcus Christl, Ángel Rodés

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Southern South America contains a glacial geomorphological record that spans the past million years and has the potential to provide palaeoclimate information for several glacial periods in Earth's history. In central Patagonia, two major outlet glaciers of the former Patagonian Ice Sheet carved deep basins ∼50 km wide and extending over 100 km into the Andean plain east of the mountain front. A succession of nested glacial moraines offers the possibility of determining when the ice lobes advanced and whether such advances occurred synchronously. The existing chronology, which was obtained using different methods in each valley, indicates the penultimate moraines differ in age by a full glacial cycle. Here, we test this hypothesis further using a uniform methodology that combines cosmogenic nuclide ages from moraine boulders, moraine cobbles and outwash cobbles. 10Be concentrations in eighteen outwash cobbles from the Moreno outwash terrace in the Lago Buenos Aires valley yield surface exposure ages of 169–269 ka. We find 10Be inheritance is low and therefore use the oldest surface cobbles to date the deposit at 260–270 ka, which is indistinguishable from the age obtained in the neighbouring Lago Pueyrredón valley. This suggests a regionally significant glaciation during Marine Isotope Stage 8, and broad interhemispheric synchrony of glacial maxima during the mid to late Pleistocene. Finally, we find the dated outwash terrace is 70–100 ka older than the associated moraines. On the basis of geomorphological observations, we suggest this difference can be explained by exhumation of moraine boulders.
Original languageEnglish
Pages (from-to)77-94
JournalQuaternary Science Reviews
Early online date3 Apr 2017
Publication statusPublished - 15 May 2017


  • Cosmogenic nuclide surface exposure dating
  • Marine isotope stage 8
  • Glacial chronology
  • Moraine degradation
  • Beryllium-10
  • Last Glacial Maximum
  • Moraine boulders


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