settings: Load settings to and from json

Description

Get and set preferred values for decay constants, isotopic abundances, molar masses, fission track etch efficiences, and etchable lengths, and mineral densities, either individually or via a .json file format.

Usage

1
settings(setting = NA, ..., fname = NA)

Arguments

setting

unless fname is provided, this should be one of either:

'lambda': to get and set decay constants

'iratio': isotopic ratios

'imass': isotopic molar masses

'mindens': mineral densities

'etchfact': fission track etch efficiency factors

'tracklength': equivalent isotropic fission track length

...

depends on the value for setting:

  • for 'lambda': the isotope of interest (one of either "fission", "U238", "U235", "Th232", "Re187", "Sm147", "Rb87", or "K40") PLUS (optionally) the decay constant value and its analytical error. Omitting these two numbers simply returns the existing values.

  • for 'iratio': the isotopic ratio of interest (one of either "Ar40Ar36", "Ar38Ar36", "Rb85Rb87", "Sr88Sr86", "Sr87Sr86", "Sr84Sr86", "Re185Re187", "Os184Os192" "Os186Os192", "Os187Os192", "Os188Os192", "Os189Os192", "Os190Os192", "U238U235", "Sm144Sm152", "Sm147Sm152", "Sm148Sm152", "Sm149Sm152", "Sm150Sm152", "Sm154Sm152", "Nd142Nd144", "Nd143Nd144", "Nd145Nd144", "Nd146Nd144", "Nd148Nd144", or "Nd150Nd144") PLUS (optionally) the isotopic ratio and its analytical error. Omitting these two numbers simply returns the existing values.

  • for 'imass': the (isotopic) molar mass of interest (one of either "U", "Rb", "Rb85", "Rb87", "Sr84", "Sr86", "Sr87", "Sr88", "Re", "Re185", "Re187", "Os", "Os184", "Os186", "Os187", "Os188", "Os189", "Os190", "Os192", "Sm" or "Nd") PLUS (optionally) the molar mass and its analytical error. Omitting these two numbers simply returns the existing values.

  • for 'mindens': the mineral of interest (one of either "apatite" or "zircon") PLUS the mineral density. Omitting this number simply returns the existing value.

  • 'etchfact': the mineral of interest (one of either "apatite" or "zircon") PLUS the etch efficiency factor. Omitting this number simply returns the existing value.

  • 'tracklength': the mineral of interest (one of either "apatite" or "zircon") PLUS the equivalent isotropic fission track length. Omitting this number simply returns the existing value.

fname

the path of a .json file

Value

if setting=NA and fname=NA, returns a .json string

if ... contains only the name of an isotope, isotopic ratio, element, or mineral and no new value, settings returns either a scalar with the existing value, or a two-element vector with the value and its uncertainty.

References

  1. Decay constants:

    • U: Jaffey, A. H., et al. "Precision measurement of half-lives and specific activities of U^{235} and U^{238}." Physical Review C 4.5 (1971): 1889.

    • Th: Le Roux, L. J., and L. E. Glendenin. "Half-life of ^{232}Th. "Proceedings of the National Meeting on Nuclear Energy, Pretoria, South Africa. 1963.

    • Sm: Lugmair, G. W., and K. Marti. "Lunar initial ^{143}Nd/^{144}Nd: differential evolution of the lunar crust and mantle." Earth and Planetary Science Letters 39.3 (1978): 349-357.

    • Nd: Zhao, Motian, et al. "Absolute measurements of neodymium isotopic abundances and atomic weight by MC-ICPMS." International Journal of Mass Spectrometry 245.1 (2005): 36-40.

    • Re: Selby, D., Creaser, R.A., Stein, H.J., Markey, R.J. and Hannah, J.L., 2007. Assessment of the 187Re decay constant by cross calibration of Re-Os molybdenite and U-Pb zircon chronometers in magmatic ore systems. Geochimica et Cosmochimica Acta, 71(8), pp.1999-2013.

    • Ar: Renne, Paul R., et al. "Response to the comment by WH Schwarz et al. on "Joint determination of ^{40}K decay constants and ^{40}Ar*/^{40}K for the Fish Canyon sanidine standard, and improved accuracy for ^{40}Ar/^{39}Ar geochronology" by PR Renne et al.(2010)." Geochimica et Cosmochimica Acta 75.17 (2011): 5097-5100.

    • Rb: Villa, I.M., De Bievre, P., Holden, N.E. and Renne, P.R., 2015. IUPAC-IUGS recommendation on the half life of ^{87}Rb. Geochimica et Cosmochimica Acta, 164, pp.382-385.

  2. Isotopic ratios:

    • Ar: Lee, Jee-Yon, et al. "A redetermination of the isotopic abundances of atmospheric Ar." Geochimica et Cosmochimica Acta 70.17 (2006): 4507-4512.

    • Rb: Catanzaro, E. J., et al. "Absolute isotopic abundance ratio and atomic weight of terrestrial rubidium." J. Res. Natl. Bur. Stand. A 73 (1969): 511-516.

    • Sr: Moore, L. J., et al. "Absolute isotopic abundance ratios and atomic weight of a reference sample of strontium." J. Res. Natl.Bur. Stand. 87.1 (1982): 1-8.

    • Sm: Chang, Tsing-Lien, et al. "Absolute isotopic composition and atomic weight of samarium." International Journal of Mass Spectrometry 218.2 (2002): 167-172.

    • Re: Gramlich, John W., et al. "Absolute isotopic abundance ratio and atomic weight of a reference sample of rhenium." J. Res. Natl. Bur. Stand. A 77 (1973): 691-698.

    • Os: Voelkening, Joachim, Thomas Walczyk, and Klaus G. Heumann. "Osmium isotope ratio determinations by negative thermal ionization mass spectrometry." Int. J. Mass Spect. Ion Proc. 105.2 (1991): 147-159.

    • U: Hiess, Joe, et al. "^{238}U/^{235}U systematics in terrestrial uranium-bearing minerals." Science 335.6076 (2012): 1610-1614.

Examples

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# load and show the default constants that come with IsoplotR
json <- system.file("constants.json",package="IsoplotR")
settings(fname=json)
print(settings())

# use the decay constant of Kovarik and Adams (1932)
settings('lambda','U238',0.0001537,0.0000068)
print(settings('lambda','U238'))

# returns the 238U/235U ratio of Hiess et al. (2012):
print(settings('iratio','U238U235'))
# use the 238U/235U ratio of Steiger and Jaeger (1977):
settings('iratio','U238U235',138.88,0)
print(settings('iratio','U238U235'))

Questions? Problems? Suggestions? or email at ian@mutexlabs.com.

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