Dry Valleys / Transantarctic Mountains data, observations, paper outlines, etc.

The point of this page is to assemble data needed to write various papers. Linked below are:

i) many spreadsheets containing cosmogenic-nuclide and other data that apply to various different possible papers, and

ii) sub-pages intended as outlines for specific papers.

Here are the links to sub-pages for individual papers:

Surface mobility in the Dry Valleys

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

1. Cosmogenic-nuclide data.

This section includes data for all samples from the Dry Valleys that Balco and/or Morgan have analysed, as well as some marginally related samples from the southern Transantarctic Mountains near Reedy Glacier (from Stone) and a variety of standards and quality-control-type measurements.

The following section on Ne-21 measurements contains very detailed data about all mass-spectrometric neon analyses, documented in two ways: Excel spreadsheets that contain complete data dumps of all step-degassing analyses as well as averaging of replicates and some other quality-control stuff; and PDFs showing step-degassing results in a form suitable for attaching to a paper's data repository.

The subsequent section contains more practical summary spreadsheets that show Al-26, Be-10, and Ne-21 measurements on all samples in a relatively compact form. These will be the most useful to actually look at.

Then there are also some density measurements. This includes the very large set of density measurements made by Dan on pit samples, as well as results of Greg processing all these data to yield mass depths for all the pit samples.

1.A. Ne-21 measurements in detail:

1.A.1. Complete step-degassing results for CRONUS-A standard (internal standard used for quality control), 2010 measurement cycle: Excel PDF

1.A.2. Complete step-degassing results for CRONUS-A standard in the 2008-09 measurement cycle are included in the data files from the production rate paper discussed below in 1.A.3.b.

1.A.3. The next three data sets contain Ne-21 data for all Dry Valleys bedrock and erratic samples. Some of these data appeared in the Balco and Shuster production rate paper in EPSL, others are in the draft elevation-transects paper, and the rest aren't anywhere yet. Overlapping subsets of these data will probably appear in any future papers.

1.A.3.a. Complete step-degassing results for Dry Valleys bedrock and erratic samples measured in the 2010 cycle. Includes an assortment of samples from Arena Valley, Wright Valley, and the western Olympus Range that weren't measured in 2008-09. Excel PDF

1.A.3.b. Complete step-degassing results for Dry Valleys bedrock samples included in the Balco and Shuster, 2009 production rate paper. This is just the data repository table from this paper. This also includes quality control measurements of the CRONUS-A standard from the 2008-09 measurement cycle. Excel PDF

1.A.3.c. Complete step-degassing results for Dry Valleys bedrock samples included in elevation transects from Mt. Dewitt and the East Groin. These are part of the draft paper on bedrock transects. This data file also includes data from an elevation transect at Reedy Glacier collected by Stone and Todd. Excel PDF

1.A.4. Finally, complete step-degassing results for all pits.

Pit 4 (measured in 2008-09): Excel PDF
Pit 6 (measured in 2008-09): Excel PDF
Pit 9 (measured in 2008-09): Excel PDF
Pit 16 (measured in 2010): Excel PDF
Pit 19 (measured in 2010): Excel PDF
Pit 20 (measured in 2010): Excel PDF
Pit 26 (measured in 2010): Excel PDF

1.B. Al-26/Be-10/Ne-21 measurements for all samples:

1.B.1. Al-26/Be-10/Ne-21 concentrations for all bedrock and erratic samples. This spreadsheet includes Al-26 and Be-10 measurements, summary average Ne-21 measurements, and supporting site and sample information. Has Be-10/Al-26 data in correct form for entering into online exposure age/erosion rate calculators. Also has production rates computed for all sites. Be careful to check KNSTD/07KNSTD when looking at Be-10 measurements and production rates in this file. Excel spreadsheet

1.B.2. Summary spreadsheet of Al-26/Be-10/Ne-21 concentrations for all pits where all three nuclides have been measured. The Al-26 and Be-10 concentrations are from Dan's previous spreadsheet. Be-10 should be on 07KNSTD, but please check. This also contains mass depths calculated by GB as discussed below. Excel spreadsheet

1.B.3. Spreadsheet prepared by Dan in Dec. 2009 and more recently annotated by Greg that shows all measured Al-26/Be-10 concentrations and some information about the existence and condition of the samples. This overlaps somewhat with the spreadsheet above. Also Be-10 should be on 07KNSTD. Excel spreadsheet

1.B.4. Spreadsheet showing locations and production rates for all pits. Note: this has been recently updated by Greg and probably has some differences with production rates Dan has been working with. Be-10 production rates are on 07KNSTD. Production rates are from 2008 calibration, Stone scaling scheme, muon scheme from online calculators. Excel spreadsheet

1.C. Density measurements for pit samples:

1.C.1. Dan's original spreadsheet containing all density measurements on pit samples. Lots of density measurements. Nice job Dan. Excel spreadsheet

1.C.2. Results of Greg's reprocessing all these data to yield mass depths for all pit samples. Two results here -- one from using the average of all packed density measurements for each sample; another from using the maximum observed density for each sample. These may be a little bit different from values Dan has already used, but the differences will not be significant. Text file

1.C.3. Automatically generated plots showing density observations for all pits. Left panel shows density (g/cm3) vs. depth (cm). White circles are un-packed; grey are packed. Black line connects average packed densities; red line connects maximum observed densities. Right panels show mass depth (g/cm2) vs. linear depth (cm). Black and red lines correspond to lines of like color in left panels.

Pit 4 PDF
Pit 5 PDF
Pit 6 PDF
Pit 7 PDF
Pit 9 PDF
Pit 11 PDF
Pit 12 PDF
Pit 14 PDF
Pit 15 PDF
Pit 16 PDF
Pit 17 PDF
Pit 19 PDF
Pit 20 PDF
Pit 22 PDF
Pit 25 PDF
Pit 26 PDF

2. Papers already written about these samples:

Putkonen J., Balco G., Morgan D., 2008. Slow regolith degradation without creep determined by cosmogenic nuclide measurements in Arena Valley, Antarctica. Quaternary Research 69, pp. 242-249. PDF

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

Morgan D., Putkonen J., Balco G., Stone J., 2010. Quantifying regolith erosion rates with cosmogenic nuclides Be-10 and Al-26 in the McMurdo Dry Valleys, Antarctica. Journal of Geophysical Research - Earth Surface 115, p. F03037. PDF

Morgan D., Putkonen J., Balco G., Stone J., 2010. Degradation of glacial deposits quantified with cosmogenic nuclides, Quartermain Mountains, Antarctica. Earth Surface Processes and Landforms. PDF

3. Some basic data interpretation:

Includes a variety of figures and tables that may be helpful in interpreting various data. Expected to change often.

3.A. Three-nuclide depth profiles and apparent age/erosion rate plots.

These plots have three panels:

The upper panel shows nuclide concentrations normalized to the surface production rate, for all three nuclides ("N*"). This is pretty much just the raw data and is intended to show the shape of the profiles and whether or not the various nuclides have comparable profile shapes. Things to look for here are i) discordance between surface and subsurface samples; ii) whether or not profiles are simple exponentials, and iii) whether or not the profiles are the same among the various nuclides.

The center panel shows the apparent exposure age of all samples in the profile, calculated using the production rates expected at the actual depths of the samples. If the site had no inheritance and experienced only a single period of steady exposure without erosion or mixing, then all samples and all nuclides would give the same apparent exposure ages. Needless to say, this doesn't happen. Various deviations from this expectation give some idea as to what else might have happened.

The lower panel shows apparent erosion rates, computed using the production rates calculated for the actual sample depths. Same deal -- if site experienced only steady erosion and no inheritance, then we would see apparent erosion rates that were the same for all samples and all nuclides. Some sites are pretty close to this.

Basically, these plots are a decent way to heuristically figure out what types of exposure models to start with for a particular pit.

Pit 4 PDF
Pit 6 PDF
Pit 9 PDF
Pit 16 PDF
Pit 19 PDF
Pit 20 PDF
Pit 26 PDF