Beryllium-10 in the Taylor Dome ice core: Applications to Antarctic glaciology and paleoclimatology

Abstract

This is an authorized facsimile, made from the miaollm master copy of the original dissertation or master thesis published by UMI. from other deep ice cores, several giaaologid issues need to be addressed.In particular, accumulation data are necessary as input for numerical iceflow-models, for determining the flux of chemical constituents from measured concentrations, and for caicuIation of the offset in age between ice and trapped air in the core.The analysis of cosmogenic beryllium-10 provides a geochemical method for constraining the accumdation-rate history at Taylor Dome.High-resolution measurements were made in shallow firn cores and snow pits to determine the relationship among beryllium-10 concentrations, wet and dry deposition mechanisms, and snow-accumulation rates.Comparison between theoretical and measured variations in deposition over the last 75 years constrains the relationship between beryllium-10 deposition and global average production rates.

Geochronology of bonney drift, taylor valley, antarctica: evidence for interglacial expansions of taylor glacier

“…In a companion paper in this issue, Higgins et al (2000) showed that Taylor Glacier has remained frozen-based during late Quaternary time; therefore its fluctuations are a barometer of ice-volume changes in this sector of the EAIS, rather than a result of changes in basal thermal conditions. Isotope records from an ice core through Taylor Dome extend into marine isotope stage (MIS) 6 (~140 ka) (Steig 1996;Steig et al 2000). The terrestrial record presented here establishes the chronology of Bonney drift, an unconsolidated diamicton that covers the floor and walls of central Taylor Valley up to an elevation of 300 m. Bonney drift documents expansion of Taylor Glacier during the penultimate interglaciation, based on uranium/thorium (U/Th) dates of lacustrine algal carbonates interbedded with glaciogenic sediments.…”

“…The δ 18 O ratio (Table 2) for some U/Th-dated samples measured by Hendy et al (1979) ranges from -35 to -43‰, indicating that the major contribution to proglacial lakes in which the carbonates formed came from Taylor Glacier meltwater. The δ 18 O record from the Taylor Dome ice core shows values between -37 and -43‰ over the last 140 ka (Steig 1996). Local alpine glaciers in the central and lower Taylor Valley would have contributed waters with much less depleted values of -25 to -33‰.…”

“…For scale, the distance between Suess and Taylor Glaciers is approximately 15 km and this portion of the valley is as much as 3 km wide. and Robinson 1978;Denton et al 1989;Steig 1996). More recently, studies at Taylor Dome and other ice core sites in Greenland and Antarctica have involved detailed climate comparisons (Bender et al 1994;Sowers and Bender 1995;Steig et al 1998).…”

On the origin and timing of rapid changes in atmospheric methane during the Last Glacial Period

“…To determine ice ages we calculated A age using the Herron and Langway [1980] model, with temperatures inferred from the oxygen isotope record and accumulation rates inferred from measurements of løBe [Steig, 1996, Steig et al, 1998]. We added A age to the gas ages to compute ice age as a function of depth.…”

Using the sunspot cycle to date ice cores

“…As an example, at a depth of 380 meters in the Taylor Dome ice core, the age is about 15,000 years [Steig, 1996]. At this depth, the annual layer thickness is about 0.2 cm and the løBe concentration is about 105 atoms per gram of ice.…”