IsoplotR (version 0.5)

isochron: Calculate and plot isochrons

Description

Plots cogenetic $^{40}$Ar/$^{39}$Ar data as X-Y scatterplots, fits an isochron curve through them using the yorkfit function, and computes the corresponding isochron age, including decay constant uncertainties.

Usage

isochron(x, ...)
"isochron"(x, xlim = NA, ylim = NA, alpha = 0.05, show.numbers = FALSE, ellipse.col = rgb(0, 1, 0, 0.5), line.col = "grey", lwd = 2, ...)
"isochron"(x, xlim = NA, ylim = NA, alpha = 0.05, show.numbers = FALSE, ellipse.col = rgb(0, 1, 0, 0.5), inverse = TRUE, plot = TRUE, ...)

Arguments

x

EITHER a list with the following vectors:

X: the x-variable

Y: the y-variable

sX: the standard error of X

sY: the standard error of Y

rXY: the correlation coefficient of X and Y

OR an object of class ArAr

...

optional arguments

xlim

2-element vector with the plot limits of the x-axis

ylim

2-element vector with the plot limits of the y-axis

alpha

confidence cutoff for the error ellipses

show.numbers

boolean flag (TRUE to show grain numbers)

ellipse.col

background colour of the error ellipses

line.col

colour of the isochron line

lwd

line width

inverse

if TRUE, plots $^{36}$Ar/$^{40}$Ar vs. $^{39}$Ar/$^{40}$Ar. If FALSE, plots $^{40}$Ar/$^{36}$Ar vs. $^{39}$Ar/$^{36}$Ar.

plot

if FALSE, suppresses the graphical output

Value

if plot=FALSE, returns a list with the following items:a: the intercept of the straight line fit and its standard errorb: the slope of the fit and its standard errory0: the atmospheric $^{40}$Ar/$^{36}$Ar ratio and its standard errorage: the $^{40}$Ar/$^{39}$Ar age and its standard error

Examples

data(examples)
isochron(examples$ArAr)