REEpatternsExplorer {GCDkit} | R Documentation |
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).
REEexplorer(x,...)
x |
numeric; a matrix or vector with the REE data |
... |
further parameters of the function |
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.
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 " |
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 |
Unused values (e.g., when tetrads are not fitted) will return NA
.
tetrad.r
Michael Anenburg, Michael.Anenburg@anu.edu.au
wrapper function for GCDkit: Vojtěch Janoušek, vojtech.janousek@geology.cz
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
For online calculations and plotting, visit ALambdaR and BLambdaR...
Also see pyrolite package for Python with REE shape coefficients capabilities (λ and τ).
sampleDataset("sazava") REEexplorer(WR)