Set up a discordance filter
Define a discordance cutoff to filter U–Pb data.
discfilter(option = 0, before = TRUE, cutoff)
option |
one of five options:
Further details in Vermeesch (2021). |
before |
logical flag indicating whether the discordance
filter should be applied before ( |
cutoff |
a two-element vector with the minimum (negative) and
maximum (positive) allowed discordance. Default values vary
between the different options. To view them, enter
|
The most reliable U–Pb age constraints are obtained from (zircon) grains whose ^{206}Pb/^{238}U and ^{207}Pb/^{206}Pb ages are statistically indistinguishable from each other. U–Pb compositions that fulfil this requirements are called ‘concordant’. Those that violate it are called ‘discordant’. The discordance of the ^{206}Pb/^{238}U and ^{207}Pb/^{206}Pb systems can be defined in five different ways. By setting a cutoff for any of these criteria, U–Pb data can be filtered for data quality.
a list with the input parameters. Default values for
cutoff are
c(-50,140) if option=='t';
c(-5,15) if option=='r';
c(-0.3,1) if option=='sk';
c(-2,6) if option=='a'; and
c(-2,7) if option=='c'.
Vermeesch (2021) “On the treatment of discordant data in detrital zircon U–Pb geochronology”, Geochronology.
cad, kde,
radialplot
dscf <- discfilter(option='c',before=TRUE,cutoff=c(-1,1))
weightedmean(x=examples$UPb,exterr=FALSE,sigdig=2,
cutoff.disc=dscf,common.Pb=3)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.