REEpatternsExplorer {GCDkit}R Documentation

REE patterns explorer (Anenburg & Williams 2022)

Description

Displays a chondrite-normalized (O'Neill et al. 2016) REE pattern for the selected sample (grey) and its approximation by polynomial fit (red) after Anenburg and Williams (2022).

Usage

REEexplorer(x,...)

Arguments

x

numeric; a matrix or vector with the REE data

...

further parameters of the function lambda.tetrad.fit

Details

Following O’Neill(2016), the chondrite-normalized patterns are constructed using eightfold coordinated “ionic radii” (in A) taken from Shannon 1976. The precise magnitudes of the Ce (Ce/Ce*) and Eu (Eu/Eu*) anomalies are al;so calculated.

The polynomial fits are defined by the λ (shape) and, optionally, τ (tetrad) coefficients (Anenburg and Williams 2022).

This is merely a crude interface to the graphical output provided by the function lambda.tetrad.fit written by M. Anenburg that does all the work.

REEexplorer.png

Value

Returns a numeric vector with the following columns:

adj.r2

Adjusted r-squared.

red.chi.sq

Reduced χ^2. The magnitude of this parameter depends on the "uncert" setting. This parameter is occasionally referred to as MSWD (mean squared weighted deviation).

lambda0, lambda1, lambda2, lambda3, lambda4

Lambda shape coefficients (λ_0, λ_1, λ_2, λ_3, λ_4).

tau1, tau2, tau3, tau4

Tetrad coefficients (τ_1, τ_2, τ_3, τ_4).

lambda0.se, lambda1.se, lambda2.se, lambda3.se, lambda4.se

Standard errors for lambda coefficients.

tau1.se, tau2.se, tau3.se, tau4.se

Standard errors for tau coefficients.

lambda0.pval, lambda1.pval, lambda2.pval, lambda3.pval, lambda4.pval

p-values for lambda coefficients.

tau1.pval, tau2.pval, tau3.pval, tau4.pval

p-values for tau coefficients. Typically, all four tetrads should have the same sign (positive or negative), and about the same magnitude. Only occasionally, τ_1 is of a larger magnitude than τ_2 to τ_4.

La_MFR, Ce_MFR, Pr_MFR, Nd_MFR...

Measured-to-fit-ratios for all REE. This takes the ratio of individual normalised REE and compares them to hypothetical REE contents derived from the polynomial fit. These values should be as close to 1 as possible. If Ce or Eu are far from unity, it may indicate a Ce or Eu anomaly, and the cean or euan arguments should be set to TRUE to remove them from the fitting procedure, and improve the fit for all other elements. In this case, Ce_MFR and Eu_MFR are the anomaly magnitudes (often referred to as Ce/Ce* and Eu/Eu*). If any other elements are consistently far from 1, this could indicate (1) presence of tetrad effect, (2) noisy data, (3) oxide interferences of LREE on the HREE.

Unused values (e.g., when tetrads are not fitted) will return NA.

Plugin

tetrad.r

Author(s)

Michael Anenburg, Michael.Anenburg@anu.edu.au

wrapper function for GCDkit: Vojtěch Janoušek, vojtech.janousek@geology.cz

References

Anenburg M, Williams MJ (2022) Quantifying the tetrad effect, shape components, and Ce-Eu-Gd anomalies in Rare Earth Element patterns. Math Geosci 54:47-70 doi: 10.1007/s11004-021-09959-5

O'Neill HS (2016) The smoothness and shapes of chondrite-normalised rare earth element patterns in basalts. J Petrol 57:1463-1508. doi: 10.1093/petrology/egw047

Shannon R (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst Sect A 32:751-767 doi: 10.1107/S0567739476001551

See Also

lambdaTetradFit

tetradAnenburg

For online calculations and plotting, visit ALambdaR and BLambdaR...

spider

tetrad

Also see pyrolite package for Python with REE shape coefficients capabilities (λ and τ).

Examples

    sampleDataset("sazava")
    REEexplorer(WR) 

[Package GCDkit version 6.3.0 Index]