Subdivision of glacial deposits in southeastern Peru based on pedogenic development and radiometric ages

TitleSubdivision of glacial deposits in southeastern Peru based on pedogenic development and radiometric ages
Publication TypeJournal Article
Year of Publication2001
AuthorsGoodman, AY, Rodbell, DT, Seltzer, GO, Mark, BG
JournalQuaternary Research
Date PublishedJul
Accession NumberWOS:000169861000004

The Cordillera Vilcanota and Quelccaya Ice Cap region of southern Peru (13 degrees 30'-14 degrees 00'S; 70 degrees 40'-71 degrees 25'W) contains a detailed record of late Quaternary glaciation in the tropical Andes, Quantification of soil development on 19 moraine crests and radiocarbon ages are used to reconstruct the glacial history. Secondary iron and day increase linearly in Quelccaya soils and clay accumulates at a linear rate in Vilcanota soils, which may reflect the semicontinuous addition of eolian dust enriched in secondary iron to all soils. In contrast, logarithmic rates of iron buildup in soils in the Cordillera Vilcanota reflect chemical weathering; high concentrations of secondary iron in Vilcanota tills may mask the role of eolian input to these soils. Soil-age estimates from extrapolation of field and laboratory data suggest that the most extensive late Quaternary glaciation occurred >70,000 yr B.P. This provides one of the first semiquantitative age estimates for maximum ice extent in southern Peru and is supported by a minimum-limiting age of similar to 41,520 C-14 yr B.P. A late glacial readvance culminated similar to 16,650 cal yr B.P. in the Cordillera Vilcanota, Following rapid deglaciation of unknown extent, an advance of the Quelccaya Ice Cap occurred between similar to 13,090 and 12,800 cal yr B.P., which coincides approximately with the onset of the Younger Dryas cooling in the North Atlantic region. Moraines deposited <394 cal yr B.P. in the Cordillera Vilcanota and <300 cal yr B.P. on the west side of the Quelccaya Ice Cap correlate with Little Ice Age moraines of other regions. (C) 2001 University or Washington.