High net accumulation rates at Campo deHielo Patagόnico Sur, South America, revealed by analysis of a 45.97 m long ice core

Abstract

A 45.97 m long ice core was recovered in the accumulation area of Glaciar Tyndall (50˚59’05’’ S, 73˚31’12’’W; 1756ma.s.l.), Campo de Hielo Patagόnico Sur (southern Patagonia icefield), during December 1999. the firn core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to analyses of water isotopes (δ18O, δD), major dissolved ions and snow algal biomass. the drillhole remained dry down to about 43 m depth, where a water-soaked layer appeared. Seasonal cycles were found for δ18O, δD and the D-excess, although the amplitudes of the cycles decreased with depth. Major dissolved ions (Na+, K+, Mg2+, Ca2+, Cl–, SO42–) and algal biomass exhibit rapid decreases in the upper 3 m, probably due to meltwater elution. Annual increments defined by the δ18O and D-excess peaks suggest that the minimum net accumulation rates at this location were 17.8ma–1 in 1997/98–1998/99 and 411.0 ma–1 in 1998/99–1999/2000. These are much higher values than those previously obtained from past ice-core studies in Patagonia, but are of the same order of magnitude as those predicted from various observations in ablation areas of Patagonian glaciers.

Glacier mass balance interpreted from biological analysis of firn cores in the Chilean lake district

“…Maximum biovolume in the ice core is 1.4 Â 10 3 mm 3 mL -1 . Algal biovolume values from the volcano summits are similar to those reported in other studies of ice cores such as at Yala glacier (Yoshimura and others, 2000), Glaciar Tyndall (Shiraiwa and others, 2002;Kohshima and others, 2007) and Sofiyskiy glacier (Uetake and others, 2006).…”

A promising location in Patagonia for paleoclimate and paleoenvironmental reconstructions revealed by a shallow firn core from Monte San Valentín (Northern Patagonia Icefield, Chile)

“…Data previously published for NPI and SPI reveal accumulation rates of several meters of snow per year [Matsuoka and Naruse, 1999;Popovnin et al, 1999;Shiraiwa et al, 2002;Yamada, 1987]. Net snow accumulation rates are lower at the highest drilling sites on SPI, that are Moreno (2000 m, 1.2 m w.eq.)…”

“…A 14.5-m deep core was drilled at Nef Glacier (1500 m) and a 37.6-m deep core was drilled at San Rafael Glacier (1300 m) on the NPI, but they were found not suitable for paleoclimate reconstructions due to large annual accumulation rates (2.2 m w.eq and 3.5 m w.eq., respectively) and alteration by water percolation [Matsuoka and Naruse, 1999;Yamada, 1987]. A similar problem was encountered near the ice divide at Tyndall Glacier on the SPI where the highest accumulation rate observed in Patagonia was found at an altitude of 1760 m from a 43-m long core [14 m w.eq., Shiraiwa et al, 2002]. At those three sites (Nef, San Rafael and Tyndall) a watersoaked layer was found at the firn/ice interface, which constitutes a water table as it is typically found in the lower accumulation area of temperate glaciers [e.g.…”

Holocene glaciations of Hielo Patag^|^oacute;nico (Patagonia Icefield), South America: A brief review

“…The mass balance was estimated at 6000-8000 mm from drillings (Yamada, 1987;Matsuoka and Naruse, 1999;Shiraiwa et al, 2002) and satellite image analysis (Rott et al, 1998), while from hydrological balance it was estimated at 6000-7400 mm (Escobar et al, 1992). Nichols and Miller (1951), who visited Glaciar Ameghino in the HPS (Fig.…”