Cosmogenic noble gas measurements from Ong Valley and Moraine Canyon, central Transantarctic Mountains

This page archives cosmogenic noble gas measurements from two sites in the Transantarctic Mountains, Ong Valley and Moraine Canyon. These data were collected as part of a U.S. National Science Foundation funded project entitled "Systematic analysis of landscape evolution and surface ages in the southern Transantarctic Mountains," with PIs Jaakko Putkonen (University of North Dakota), Greg Balco (Berkeley Geochronology Center), and David Shuster (Berkeley Geochronology Center and University of California Berkeley).

Link to proposal project description: PDF

Questions on this page: Greg Balco, balcs@bgc.org


1. Cosmogenic Ne-21 analyses on quartz from surface and subsurface samples of unconsolidated glacial sediment in Ong Valley.

This includes data from six sites in Ong Valley where a field party led by Putkonen collected sediment from shallow (~1 m) pits in unconsolidated glacial sediment. Pure quartz separates were subsequently extracted from these samples by sieving, heavy liquid and magnetic separation, and differential etching in dilute hydrofluoric acid. Cosmogenic Ne-21 measurements were made at BGC in May and June 2013.

Notes:

1. Details of cosmogenic Ne-21 measurements at BGC can be found in the following reference:

Balco, G. Shuster, D.L., 2009. Production rate of cosmogenic Ne-21 in quartz estimated from Be-10, Al-26 and Ne-21 concentrations in slowly eroding Antarctic bedrock surfaces. Earth and Planetary Science Letters 281, pp. 48-58. PDF Supplementary figures Supplementary table

2. BGC has two mass spectrometer/noble gas extraction systems configured for cosmogenic Ne-21 measurements.These measurements were made on the older of the two (the "MAP II" system, whereas the measurements described in the next sections were made on the newer (the "Ohio" system). The two systems were independently calibrated and there is a small systematic difference between cosmogenic Ne-21 concentrations measured on each system. Measurements of the "CRONUS-A" and "CREU-1" quartz standards described below can be used to correct for this offset.

3. We analysed the "CRONUS-A" quartz standard during the period of these measurements; results are reported with the samples below. A discussion of the interlaboratory reproducibility of Ne-21 concentrations in CRONUS-A appears in this reference:

Vermeesch P., Balco G., Blard P-H., Dunai T.J., Kober F., Niedermann S., Shuster D.L., Strasky S., Stuart F.M., Wieler R., Zimmermann L., 2013 in press. Interlaboratory comparison of cosmogenic Ne-21 in quartz. Quaternary Geochronology. PDF preprint

Complete results of step-degassing Ne-21 measurements (PDF format):

Analyses of CRONUS-A quartz standard

Samples from Ong Valley Pit 1

Samples from Ong Valley Pit 2

Samples from Ong Valley Pit 3

Samples from Ong Valley Pit 6

Samples from Ong Valley Pit 11

Samples from Ong Valley Pit 12

Spreadsheet containing these data with summary information:

Excel spreadsheet

Figure showing depth-concentration profiles from all pits:

PDF


2. Cosmogenic Ne-21 analyses on surface bedrock and glacial erratics from Ong Valley.

This includes data from surface samples of bedrock (intended for estimating rock surface erosion rates) and glacially transported boulders (intended for exposure-dating of glacial landforms). Pure quartz separates were extracted from these samples by sieving, heavy liquid and magnetic separation, and differential etching in dilute hydrofluoric acid. Cosmogenic Ne-21 measurements were made at BGC in March, 2014.

Notes:

1. BGC has two mass spectrometer/gas extraction systems configured for cosmogenic Ne-21 measurements. These measurements were made on the newer of the two (the "Ohio" system), whereas the measurements described in the previous section were made on the older of the two. The two systems were independently calibrated and there is a small systematic difference between cosmogenic Ne-21 concentrations measured on each system. Measurements of the "CRONUS-A" and "CREU-1" quartz standards (see the Vermeesch et al. paper linked above) can be used to correct for this offset.

Complete results of step-degassing Ne-21 measurements (PDF format):

Analyses of CRONUS-A and CREU-1 quartz standards

Analyses of samples of erratic boulders

Analyses of samples of surface bedrock

Spreadsheet containing these data with summary information:

Excel spreadsheet


3. Cosmogenic Ne-21 analyses on quartz from surface and subsurface samples of unconsolidated glacial sediment in Moraine Canyon

This includes data from five sites in Moraine Canyon where a field party led by Putkonen collected sediment from shallow (~1 m) pits in unconsolidated glacial sediment. Pure quartz separates were subsequently extracted from these samples by sieving, heavy liquid and magnetic separation, and differential etching in dilute hydrofluoric acid. Cosmogenic Ne-21 measurements were made at BGC in April 2014.

Notes:

1. BGC has two mass spectrometer/gas extraction systems configured for cosmogenic Ne-21 measurements. These measurements were made on the newer of the two (the "Ohio" system), whereas the measurements described in the previous section were made on the older of the two. The two systems were independently calibrated and there is a small systematic difference between cosmogenic Ne-21 concentrations measured on each system. Measurements of the "CRONUS-A" and "CREU-1" quartz standards (see the Vermeesch et al. paper linked above) can be used to correct for this offset.

Complete results of step-degassing Ne-21 measurements (PDF format):

Analyses of CRONUS-A and CREU-1 quartz standards

Samples from Moraine Canyon Pit 13

Samples from Moraine Canyon Pit 14

Samples from Moraine Canyon Pit 15

Samples from Moraine Canyon Pit 16

Samples from Moraine Canyon Pit 17

Spreadsheet containing these data with summary information:

Excel spreadsheet

Figure showing depth-concentration profiles from all pits:

PDF