Documentation for Reedy Glacier Exposure Ages, Version 1

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Detailed Data Description

The samples used for this data set come primarily from glacial moraines and recessional deposits formed during the last glacial period (Marine Isotope Stage 2) and its termination. Geographical coverage extends from Cohen Nunatak at the northwest (lower) end of the glacier to Hatcher Bluffs at its head.The data are formatted as input for the CRONUS online exposure-age calculator, which determines the exposure age from the cosmogenic Be-10 and Al-26 production rates. Samples were collected during the 2003-04 and 2004-05 Antarctic field seasons, processed in the University of Washington Cosmogenic Nuclide Laboratory and analyzed for Be-10 at the Lawrence Livermore National Laboratory Center for Accelerator Mass Spectrometry, and PRIME Lab, Purdue University.

Format

Data are provided in a Microsoft Excel (.xlsx) file.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0601_stone directory. The worksheet contains the location information, density, sample thickness, shielding correction, Be-10, Al-26, and isostatic correction for Be-10 values for each sample.

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File Size

The file size is 61 KB.

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Spatial Coverage

Southernmost Latitude: 86.51° S
Northernmost Latitude: 85.38° S
Westernmost Longitude: 124.48° E
Easternmost Longitude: 136.32° E

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Temporal Coverage

Paleo temporal coverage is from 20,000 B.P. to present.
Data were collected from 01 November 2003 through 31 January 2005.

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Parameter or Variable

Beryllium-10 (Be-10)
Aluminum-26 (Al-26) Analysis

Sample Data Record

Refer to Figure 1 for an example of the data.

sample data
Figure 1. Reedy Glaciers Exposure Ages Data
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Software and Tools

The data can be accessed using Microsoft Excel.

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Data Acquisition and Processing

Data Acquisition Methods

Samples were collected from 01 November 2003 through 31 January 2005. A hand-held GPS determined the geographic co-ordinates; altitudes were estimated from drift-corrected barometer traverses between reference sites where elevations were established with survey-grade GPS receivers. Elevations are in meters above sea level, and elevation uncertainties were estimated at less than ± 5 meters. Erosion rates were inferred to be zero based on sample surface preservation. Samples have been assigned a density of 2.7 g/cm3; actual densities were not measured. Actual density differences are likely to be small and have an effect of <1% on final exposure-age estimates.

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Derivation Techniques and Algorithms

Processing Steps

Beryllium was extracted and purified using conventional procedures (see: http://depts.washington.edu/cosmolab/chem/Al-26_Be-10.pdf). Be-10 was measured in clean quartz separates. Beryllium isotope ratios were measured relative to several different reference standards; Be-10 concentrations presented here have been corrected to a common basis relative to the KNSTD3110 standard (KNSTD-5-4) with an assumed Be-10/Be-9 ratio = 2.851*10-12. See Nishiizumi et al. (2007) and CRONUS calculator documentation: http://hess.ess.washington.edu/math/docs/al_be_v22/AlBe_standardization_table.pdf for further details.

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References and Related Publications

Contacts and Acknowledgments

Dr. John Stone
University of Washington
Dept of Earth and Space Sciences
Box 351310
Seattle, Washington 98195-1310

Acknowledgments: 

This research was supported by NSF Division of Polar Programs, Grant Number OPP-0229314.

Document Information

Document Creation Date

22 January 2015