Description Usage Arguments Details Value See Also Examples
Produces a plot of boxes whose widths correspond to the cumulative amount of ^{39}Ar (or any other variable), and whose heights express the analytical uncertainties. Only propagates the analytical uncertainty associated with decay constants and Jfactors after computing the plateau composition.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16  agespectrum(x, ...)
## Default S3 method:
agespectrum(x, alpha = 0.05, plateau = TRUE,
random.effects = TRUE, levels = NA, clabel = "",
plateau.col = c("#00FF0080", "#FF000080"),
non.plateau.col = "#00FFFF80", sigdig = 2, line.col = "red",
lwd = 2, title = TRUE, show.ci = TRUE,
xlab = "cumulative fraction", ylab = "age [Ma]", hide = NULL, ...)
## S3 method for class 'ArAr'
agespectrum(x, alpha = 0.05, plateau = TRUE,
random.effects = TRUE, levels = NA, clabel = "",
plateau.col = c("#00FF0080", "#FF000080"),
non.plateau.col = "#00FFFF80", sigdig = 2, exterr = TRUE,
line.col = "red", lwd = 2, i2i = FALSE, hide = NULL, ...)

x 
a threecolumn matrix whose first column gives the amount of ^{39}Ar in each aliquot, and whose second and third columns give the age and its uncertainty. OR an object of class 
... 
optional parameters to the generic 
alpha 
the confidence level of the error bars/boxes and confidence intervals. 
plateau 
logical flag indicating whether a plateau age should
be calculated. If 
random.effects 
if if 
levels 
a vector with additional values to be displayed as different background colours of the plot symbols. 
clabel 
label of the colour legend 
plateau.col 
a vector of two fill colours of the rectangles
used to mark the steps belonging to the age plateau. If

non.plateau.col 
if 
sigdig 
the number of significant digits of the numerical
values reported in the title of the graphical output (only used
if 
line.col 
colour of the average age line 
lwd 
width of the average age line 
title 
add a title to the plot? 
show.ci 
show a 100(1α)% confidence interval for the plateau age as a grey band 
xlab 
xaxis label 
ylab 
yaxis label 
hide 
vector with indices of aliquots that should be removed from the plot. 
exterr 
propagate the external (decay constant and calibration factor) uncertainties? 
i2i 
‘isochron to intercept’:
calculates the initial (aka ‘inherited’,
‘excess’, or ‘common’) ^{40}Ar/^{36}Ar ratio from
an isochron fit. Setting 
IsoplotR
defines the ‘plateau age’ as the weighted mean age
of the longest sequence (in terms of cumulative ^{39}Ar
content) of consecutive heating steps that pass the modified
Chauvenet criterion (see weightedmean
). Note that
this definition is different (and simpler) than the one used by
Isoplot
(Ludwig, 2003). However, it is important to mention
that all definitions of an age plateau are heuristic by nature and
should not be used for quantitative inference.
If plateau=TRUE
, returns a list with the following
items:
a 3element vector with:
x
: the plateau mean
s[x]
: the estimated standard deviation of x
ci[x]
: the width of a 100(1α)% confidence interval of
t
a 3element vector with:
w
: the overdispersion, i.e. the standard deviation of the
Normal distribution that is assumed to describe the true ages.
ll
: the width of the lower half of a 100(1α)%
confidence interval for the overdispersion
ul
: the width of the upper half of a 100(1α)%
confidence interval for the overdispersion
the degrees of freedom for the weighted mean plateau fit
the mean square of the weighted deviates of the plateau
the pvalue of a Chisquare test with df=n2 degrees of freedom, where n is the number of steps in the plateau and 2 degrees of freedom have been removed to estimate the mean and the dispersion.
the fraction of ^{39}Ar contained in the plateau
plot parameters for the weighted mean (see
weightedmean
), which are not used in the age
spectrum
indices of the steps that are retained for the plateau age calculation
1 2 
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.