Cosmogenic nuclide exposure ages for moraines in the Lago San Martin Valley, Argentina
2011 (English)In: Quaternary Research, ISSN 0033-5894, E-ISSN 1096-0287, Vol. 75, no 3, 636-646 p.Article in journal (Refereed) Published
At several times during the Quaternary, a major eastward-flowing outlet glacier of the former Patagonian Ice Sheet occupied the Lago San Martin Valley in Argentina (49 degrees S, 72 degrees W). We present a glacial chronology for the valley based on geomorphological mapping and cosmogenic nuclide ((10)Be) exposure ages (n = 10) of boulders on moraines and lake shorelines. There are five prominent moraine belts in the Lago San Martin Valley, associated with extensive sandar (glaciofluvial outwash plains) and former lake shorelines. Cosmogenic nuclide exposure ages for boulders on these moraines indicate that they formed at 14.3 +/- 1.7 ka, 22.4 +/- 2.3 ka, 34.4 +/- 3.4 ka to 37.6 +/- 3.4 ka (and possibly 60 +/- 3.5 ka), and 99 +/- 11 ka (1 sigma). These dated glacier advances differ from published chronologies from the Lago San Martin Valley based on (14)C age determinations from organic sediments and molluscs in meltwater channels directly in front of moraines or in kettleholes within end moraine ridges. The moraine boulder ages also point to possible pre-LGM glacial advances during the last glacial cycle and a key observation from our data is that the LGM glaciers were probably less extensive in the Lago San Martin Valley than previously thought.
Place, publisher, year, edition, pages
2011. Vol. 75, no 3, 636-646 p.
Cosmogenic nuclide exposure ages, Glacial chronology, Glacial geomorphology, Moraines, Patagonia
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:su:diva-68528DOI: 10.1016/j.yqres.2010.11.005ISI: 000290831500026OAI: oai:DiVA.org:su-68528DiVA: diva2:473236
authorCount :62012-01-052012-01-042012-01-05Bibliographically approved