Holocene glacial chronology of Upsala Glacier at Peninsula Herminita, Southern Patagonia Icefield

A new scheme of Holocene glacial chronology was presented for Upsala Glacier of the Southern Patagonia Icefield, South America. Five peat samples collected from moraines for 14 C dating were used to examine the Holocene glacial chronology established by Mercer in 1965. The new scheme proposed in this study calls for four Neoglaciations, Neoglaciation I, Herminita, Pearson I and Pearson II, and the change in the age assignment of the Pearson I glaciation. Although the existence of a first Neoglaciation at ca. 3600 yr B.P. was not directly confirmed by landforms and additional 14 C datings, because its extent was less than the second one, the 14 C data from other glaciers strongly suggest that there could have been a glacial advance at this date at Upsala Glacier. A second Neoglaciation, Herminita advance, which was first identified in 1990, was for the first time dated in this study to be ca. 2400-2200 yr B.P., agreeing well with other glaciers in Patagonia. A third Neoglaciation represented by the Pearson I moraines (with substages, a, b, c) occurred at least ca. 1600-1400 yr B.P., although it was long established to be ca. 2300 yr B.P. by Mercer. These dates are close to a third Neoglaciation proposed by Clapperton and Sugden in 1988 for the Andes. Since there is another date, ca. 900 yr B.P, which probably belongs to the Pearson Ic, the third glaciation may have lasted very long, close to 700 years, with oscillations. A fourth one, the Pearson II, is taken as the same as the Mercer's scheme, that is, A.D. 1600-1760.