central: Calculate U-Th-He (and fission track) central ages and compositions

Description

Computes the geometric mean composition of a set of fission track or U-Th-He data and returns the corresponding age and fitting parameters.

Usage

central(x, ...)
# S3 method for default
central(x, ...)
# S3 method for UThHe
central(x, ...)
# S3 method for fissiontracks
central(x, mineral = NA, ...)

Arguments

an object of class UThHe or fissiontracks

...

optional arguments

mineral

setting this parameter to either apatite or zircon changes the default efficiency factor, initial fission track length and density to preset values (only affects results if x$format=2.)

Value

a list containing the following items:

mswd: the reduced Chi-square statistic of data concordance, i.e. $mswd=SS/(2n-2)$, where $SS$ is the sum of squares of the log[U/He]-log[Th/He] compositions and $n$ is the number of samples. If x has class fissiontracks, then $mswd=X^2/(n-1)$, where $X^2$ is a Chi-square statistic of the EDM data or ICP ages.
p.value: the p-value of a Chi-square test with $n-2$ degrees of freedom
age: a two-column vector with the central age and its standard error.

Additionally, if x has class UThHe:

uvw: (if the input data table contains Sm) or uv (if it doesn't): the geometric mean log[U/He], log[Th/He] (, log[Sm/He]) and log[Sm/He] composition
covmat: the covariance matrix of uvw or uv

OR, if x has class fissiontracks:

disp: the (over)dispersion of the ages (value between 0 and 1)

Examples

Run this code

data(examples)
print(central(examples$UThHe)$age)

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