Documentation for Tephra in Siple and Taylor Dome Ice Cores, Version 1

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Detailed Data Description

Format and File Sizes

Geochemical analyses are in tab-delimited ASCII and Excel formats.

  • "sipleA_tephra.txt" (ASCII file, 5 KB)
  • "sipleA_tephra.xls" (Excel file, 37 KB)
  • "sipleA*.tif" (TIFF files of backscattered electron images, 139 KB to 890 KB)

Geochemical analyses have following data fields:

  • Depth of samples (m). If the sample name contains "filter" then depth is given in the "Top depth in core" column.
  • Number of geochemical analyses per sample
  • Mean and standard deviation of geochemical composition in percentage weight (normalized to 100 percent)

Note: the number next to the sample name (for example, "sipleA 34.4-34.7") indicates the sample depth in meters.

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Spatial Coverage

Tephra samples were collected from Siple Dome (81° S, 148° W) and Taylor Dome (77° 48' S, 158° 43' E).

Study Area Location Map

Siple and Taylor Domes, Antarctica

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Temporal Coverage

Cores were taken during the 1999-2000 field season.

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Parameter or Variable

Data consist of electron microprobe analyses of glass shards where compositionally-consistent samples were present. The following variables are reported:

  • Depth of samples (m). If the sample name contains "filter" then depth is given in the "Top depth in core" column.
  • Number of geochemical analyses per sample
  • Mean and standard deviation of geochemical composition in percentage weight (normalized to 100 percent)
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Software and Tools

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Data Acquisition and Processing

Electron microprobe analyses and backscatter electron images were processed with a Cameca SX-100 microprobe. Geochemical quantities are reported in percentage weight and normalized to 100 percent. Na2O is normalized to the value obtained by neutron activation analysis. Analytical precision, based on replicate analyses of standard reference materials of similar composition to the unknowns, is as follows (in percentage weight):

SiO2±0.47
TiO2±0.03
FeO±0.06
MnO±0.06
MgO±0.07
CaO±0.02
Na2O±0.55
K2O±0.27
P2O5±0.02
Cl±0.07

Preprocessing for electron microprobe analysis was conducted by irradiating neutron activation samples at the University of Missouri Research Reactor. Separated samples were analyzed at the New Mexico Institute of Mining and Technology. Irradiation lasted approximately 40 hours at a flux of 2.5 x 1013N cm-2 s-1. Analytical errors, based on replicate analysis of samples, to 1σ, are as follows:

Major elements (percentage weight):

FeO ± 0.01
Na2O ± 0.04

Trace elements (ppm):

Sc±0.04
Cr±12
Co±0.13
Ni±1
Zn±1
As±0.7
Br±0.07
Rb±0.8
Sr±0.7
Sb±0.1
Cs±1.4
Ba±10
La±1.8
Ce±1.4
Nd±0.7
Sm±0.07
Eu±0.14
Tb±0.02
Yb±0.07
Lu±0.01
Hf±0.12
Ta±0.04
Ta±0.04
W±0.05
U±0.02
Th±1

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References and Related Publications

Contacts and Acknowledgments

Nelia W. Dunbar
New Mexico Institute of Mining and Technology
E&ES Department
Socorro, NM 87801 USA

Acknowledgments: 

This research was supported by NSF grant OPP-9615167 ("Volcanic Record from the Siple and Taylor Dome Ice Cores, Antarctica").

Document Information

DOCUMENT CREATION DATE

June 2002