Information for burial.m calculating simple exposure and burial durations for combined 10Be and 26Al
measurements. The calculator is fixed by Jakob Heyman (jakob.heyman@gu.se) 2015-2019 mainly based on
the CRONUS calculator (Balco et al. 2008) and the LSD production rate scaling (Lifton et al. 2014).


TO USE THE CALCULATOR:
1. Fix the input.txt file (see below).
2. Set plot option parameters in lines 15-20 for banana plot (1 or 0).
3. Run burial.m in Octave or Matlab.
4. Simple exposure and burial durations (yr) are saved in out-burial.txt


The calculator is based on the CRONUS calculator (Balco et al. 2008) with some modifications:
* Nuclide-specific LSD spallation and muon production rate scaling based on simulated cosmic ray
  fluxes (Lifton et al. 2014).
* Time-constant spallation production rate based on RcEst value with expage global average reference
  production rates. Note that this is different from the expage exposure age calculator using a
  time-dependent spallation production rate. As the 26/10 exposure and burial uncertainties are
  generally large, the error introduced by this simplification is insignificant.
* Time-constant muon production rate parameterization (modified to reduce near-surface artifacts)
  based on Antarctica depth profile data (Borchers et al. 2016; Marrero et al. 2016; Phillips et al.
  2016) with fstar and sigma0 calibrated using muclib.m.
* Atmospheric pressure based on sample elevation and ERA-40 re-analysis dataset ('std'), Antarctica
  best-fit interpolation ('ant') (Balco et al. 2008), or given directly ('pre') in hPa.
* Attenuation length for calculating the spallation production rate adjustments for sample thickness
  and erosion rate interpolated from atmospheric pressure and cutoff rigidity (Marrero et al. 2016).
* A simple history is assumed with one constant (zero erosion) duration of exposure followed by one
  period of burial (until sampling). To get the burial duration the 26/10 ratio is back-projected to
  the simple exposure line. Burial is calculated from -10 Ma to 10 Ma, where sample 26/10 ratios
  above the simple exposure line yield negative burial durations. The projected 10Be concentration
  is used to calculate the simple exposure duration. To estimate the burial and simple exposure
  duration uncertainties a Monte Carlo simulation approach (100000 mc runs) is adopted including the
  10Be and 26Al concentration uncertainties and the reference production rate uncertainties.


INPUT INSTRUCTIONS:
The input is similar to the input for the CRONUS calcuator version 2 (Balco et al. 2008), with the
addition of sampling year. Each row in input.txt is one sample and should contain 15 or 16 columns
with the following information:
1. Sample name - (strange characters may cause problems).
2. Latitude [DD (WGS84)] - North latitudes are positive. South latitudes are negative.
3. Longitude [DD (WGS84)] - East longitudes are positive. West longitudes are negative.
4. Elevation/pressure [m a.s.l. / hPa].
5. Elevation/pressure flag - std/ant/pre (ERA40 elev interpol/Antarctica elev/atmospheric pressure).
6. Sample thickness [cm].
7. Sample density [g/cm3].
8. Correction factor - Unitless factor used for topo/geom shielding correction (no shielding -> 1).
9. 10Be concentration [atoms/g] - (if no 10Be measurement: use 0).
10. 10Be concentration uncertainty [atoms/g] - (if no 10Be measurement: use 0).
11. 10Be standardization - See make_consts_expage.m lines 34-38 for acceptable names and values.
12. 26Al concentration [atoms/g] - (if no 26Al measurement: use 0).
13. 26Al concentration uncertainty [atoms/g] - (if no 26Al measurement: use 0).
14. 26Al standardization - See make_consts_expage.m lines 41-42 for acceptable names and values.
15. Sampling year [CE].
If using 16 columns:
9. Any number (NOT USED - option included to allow for standard expage input)
10-16. See 9-15 above.


OUTPUT INFORMATION:
The calculator saves simple exposure plus burial durations and/or simple erosion rates plus burial
durations in the file out-burial.txt.
If exposure_burial = 1 (line 20 in burial.m): simple exposure and burial durations (yr).
If erosion_burial = 1 (line 21 in burial.m): simple erosionrates (mm/ka) and burial durations (yr).
Samples with no simple exposure/erosion solution yield '-' in the output.
Samples with 10Be and/or 26Al concentration = 0 yield '-' in the output.
If normNout = 1 (line 32 in burial.m), the calculator will also save sample concentrations and
uncertainties normalized to the sample production rate (for later plotting).
