Siple Dome Core Date from Measurement of the d18O of Paleoatmospheric Oxygen

Summary

This data set is part of the West Antarctic Ice Sheet Cores (WAISCORES) project, an NSF-funded project to understand the influence of the West Antarctic ice sheet on climate and sea level change. WAISCORES researchers acquired and analyzed ice core samples from the Siple Dome, in the Siple Coast region, West Antarctica. This data set includes a timescale record for the Siple Dome ice core. This chronology is derived by measuring the delta oxygen-18 of paleoatmospheric oxygen (δ18Oatm) then correlating those measurements to the Greenland Ice Sheet Project 2 (GISP2) record by adjusting the Siple Dome timescale so that its curve of δ18Oatm coincided with that of GISP2. The replicate samples were measured at 1 to 1.5 kiloyear (kyr) resolution for the length of the core. Because of core relaxation and cracking at the surface associated with gas loss and a small fractionation of O isotopes associated with loss of O2, the δ18Oatm, timescale and accuracy of the constraints of the Siple Dome control depths are subject to limited error. Data are available via FTP in Microsoft Excel (.xls) and Word (.doc) file formats.

Citing These Data

We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.

The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, publisher: NSIDC, and digital media.

Bender, M. 2004. Siple Dome Core Date from Measurement of the d18O of Paleoatmospheric Oxygen. Boulder, Colorado, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5TX3C95.

Overview Table

Category Description
Data format Microsoft Excel (.xls) and Word (.doc) files
Spatial coverage and resolution Southernmost Latitude: 81°S
Northernmost Latitude: 81°S
Westernmost Longitude: 149°W
Easternmost Longitude: 149°W
Temporal coverage and resolution Data collection: Three Antarctic field seasons in 1996 to 1999.
Data resolution: 100,000 to 100,500 years before present (ybp)
File naming convention d18Oatm.xls
d18Oatm2.xls
d18Oatm.doc
File size The data set is 528 KB total.
Parameter(s) Paleoatmospheric oxygen concentration (δ18Oatm) in parts per trillion (ppt, 1012)
Gas age in kiloannum (ka) or kiloyears (kyr)
Ice age in kiloannum (ka) or kiloyears (kyr)
Procedures for obtaining data Data are available via FTP.

Table of Contents

  1. Contacts and Acknowledgments
  2. Detailed Data Description
  3. Data Access and Tools
  4. Data Acquisition and Processing
  5. References and Related Publications
  6. Document Information

1. Contacts and Acknowledgments

Investigator(s)

Dr. Michael Bender
Princeton University
Department of Geosciences
M48 Guyot Hall
Princeton, NJ 08544
USA

Dr. James White
INSTAAR
450 UCB
University of Colorado
Boulder, CO 80309
USA

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgements

This research was supported by NSF Office of Polar Programs.

2. Detailed Data Description

Format

Data are available as Microsoft Excel (.xls) and Word (.doc) files.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/waiscores/bender/ directory. Table 1 lists the files in this directory:

Table 1. Files in the /AGDC/waiscores/bender/ directory
File Name Description
d18Oatm.xls
d18Oatm2.xls
Analytical data for paleoatmospheric oxygen, gas and ice age data, and constrained timescale of ice core chronology
d18Oatm.doc Graphical representation of time series records, in kiloyears (kyr), for Siple Dome, constrained with Vostok and GISP2 measurements, including:
  • Stable isotope ratio of paleoatmospheric oxygen (δ18Oatm) in per mil (‰)
  • Deuterium ratio of ice (δDice) in per mil (‰)
  • Stable isotope ratio of oxygen in ice(δ18Oice) in per mil (‰)

File Naming Convention

The file names for the Microsoft Excel data files are d18Oatm.xls and d18Oatm2.xls. The file name for the Microsoft Word data file is d18Oatm.doc.

File Size

The data set contains three files ranging in size from 52 KB to 235 KB.

Spatial Coverage

Ice core data were collected at the Siple Dome site in the Siple Coast region of Antarctica.

Southernmost Latitude: 81°S
Northernmost Latitude: 81°S
Westernmost Longitude: 149°W
Easternmost Longitude: 149°W

Temporal Coverage

Data were obtained during three Antarctic field seasons in 1996 to 1999.

Temporal Resolution

Data was analyzed at 1,000 to 1,500 years (1–1.5 kyr) before present (ybp) resolution.

Parameter or Variable

Parameters for ice core chronology analysis include the top depth in meters (m), the delta deuterium ratio (δD) of ice core samples as provided by James White, the delta oxygen-18 ratio of paleoatmospheric oxygen (δ18Oatm) in parts per trillion (ppt), the gas age and ice age in kiloannum (ka), and the linearly interpolated gas age and ice age in kiloyears (kyr).

Sample Data Record

Below is a sample record of the ice core chronology analysis data from d18Oatm2.xls. The ice core chronology analysis is separated into six sample records: deuterium analysis from James White, gas and ice age versus depth chronology, paleoatmospheric delta oxygen-18 ratio analysis, linearly interpolated gas chronology, and ice core timescale. The ice core timescale is separated into deuterium (δD) versus ice age and paleoatmospheric delta oxygen-18 (δ18Oatm) versus gas age for plotting. Only the first four data records are shown for each sample record.

Deuterium Analysis from James White:

top depth, m d D
382.234 -218.8
382.794 -217.4
393.832 -210.5
394.332 -226.0

Gas and Ice Age versus Depth Chronology:

top depth, m Gas Age
ka
Ice Age
ka
382.234 6.1 6.7
382.794 6.1 6.7
393.832 6.3 6.9
394.332 6.3 6.9

Paleoatmospheric Delta Oxygen-18 Ratio Analysis:

Ice depth of gas sample
top depth, m
d 18Oatm-a, ppt d 18Oatm-b, ppt means of reps
d 18Oatm, ppt
59.575 0.04 0.06 0.05
119.339 -0.11 -0.01 -0.06
179.459 0.03 -0.01 0.01
239.502 0.00 0.02 0.01

Linearly Interpolated Gas Chronology:

Gas Age
control pt.
(kyr)
Gas Age
linear interp.
(kyr)
Ice Age
(kyr)
  1.0 1.6
  1.9 2.5
... ... ...
69.5 69.5 70.1
  71.0 71.6

Ice Core Timescale (dD vs. Ice Age):

Siple_ice_age Siple_dD
6.7 -218.8
6.7 -217.4
6.9 -210.5
6.9 -226.0

Ice Core Timescale (d18Oatm vs. Gas Age):

Ice depth of gas sample
top depth, m
Siple_gas_depth
Gas Age
linear interp.
Siple_gas_ageSIPLE_D18OATM
mean
d 18Oatm, ppt
Siple_18Oatm
59.575 1.0 0.05
119.339 1.9 -0.06
179.459 2.9 0.01
239.502 3.8 0.01

Error Sources

Gas loss due to core relaxation and cracking at the surface and a small fractionation of O isotopes associated with loss of O2 both contribute to the error in the δ18Oatm timescale and accuracy of the constraints of the Siple Dome control depths.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The total volume of the data set is 528 KB.

Software and Tools

Data are accessible using standard spreadsheet and word processing document software.

Related Data Collections

4. Data Acquisition and Processing

Analysis of ice core samples followed the sample processing methods described in Brook et al., 2005, to obtain measurements of the oxygen isotope ratio of paleoatmospheric O218Oatm) and the deuterium isotope ratio. Samples were then calculated for gas age and ice age to obtain the gas chronology and subjected to linear interpolation to constrain the timescale to correlate with the GISP2 record. The experimental effort involved measuring the δ18O of O2, δ15N of N2, and the O2/N2 ratio in replicate samples, at 1 to 1.5 kyr resolution for the length of the core. For more information on data acquisition methods, see the researchers' notes in the Major Findings and the References and Related Publications listed below.

5. References and Related Publications

Bender, M. L., G. Floch, J. Chappellaz, M. Suwa, J. M. Barnola, T. Blunier, G. Dreyfus, J. Jouzel, and F. Parrenin. 2006. Gas Age–Ice Age Differences and the Chronology of the Vostok Ice Core, 0–100 ka. Journal of Geophysical Research 111:D21115: doi:10.1029/2005JD006488.

Bender, M. L., B. Malaize, J. Orchardo, T. Sowers, and J. Jouzel. 1999. High Precision Correlations of Greenland and Antarctic Ice Core Records Over the Last 100 kyr. In Mechanisms of Global Climate Change, eds. P. U. Clark, R. S. Webb, and L. D. Keigwin. American Geophysical Union Geophysical Monograph 112:149–164.

Brook, E. J., J. W. C. White, A. Schilla, M. Bender, B. Barnett, J. Severinghaus, K. Taylor, R. Alley, and E. Steig. 2005. Timing of Millennial-scale Climate Change at Siple Dome, West Antarctica, During the Last Glacial Period. Quaternary Science Reviews 24:1333-1343: doi:10.1016/j.quascirev.2005.02.002.

Schilla, A. 2007. The Stable Isotopes and Deuterium Excess from the Siple Dome Ice Core: Implications for the Late Quaternary Climate and Elevation History of the Ross Sea Region, West Antarctica. Ph.D. Dissertation, Department of Geological Sciences, University of Colorado.

Schilla, A., T. Popp, J. W. C. White, M. Bender, E. Brook, E. Steig, and K. Taylor. 2002. Stable Isotope Record From Siple Dome, Antarctica. Eos, Transactions, American Geophysical Union 83(19):A32B-12.

Sowers, T., M. Bender, and D. Raynaud. 1989. Elemental and Isotopic Composition of Occluded O2 and N2 in Polar Ice. Journal of Geophysical Research 94: 5137-5150.

Table 2 list related documents that are available on the NSIDC Web site.

Table 2. Related Documents
Document Description URL
WAISCORES Project Web site http://nsidc.org/data/waiscores/
Antarctic Glaciological Data Center Data center Web site http://nsidc.org/agdc/
WAISCORES: Findings by Bender Major Findings Web page http://nsidc.org/data/waiscores/findings/bender_findings.html

6. Document Information

Acronyms

The acronyms used in this document are listed in Table 3.

Table 3. Acronyms and Abbreviations
Acronym Description
D18OATM Delta oxygen-18 ratio of paleoatmospheric oxygen, δ18Oatm
DD Delta deuterium ratio, δD
.DOC Microsoft Word document file extension
FTP File Transfer Protocol
GISP2 Greenland Ice Sheet Project 2
KA Kiloannum, 103
KYR Kiloyears, 103
NSF National Science Foundation
NSIDC National Snow and Ice Data Center
Per mil, one part per thousand, 10-3
URL Uniform Resource Locator
WAISCORES Western Divide West Antarctic Ice Cores
.XLS Microsoft Excel spreadsheet file extension
YBP Years before present

Document Creation Date

28 December 2009

Document URL

http://nsidc.org/data/docs/agdc/nsidc0123_bender/index.html