tetradAnenburg {GCDkit} | R Documentation |
Fits orthogonal polynomial functions (shape components λ) to REE patterns normalized to average chondritic composition of O'Neill et al. (2016). The tetrad effect is quantified using the tetrad coefficients (τ).
tetradAnenburg(x,...)
x |
numeric; a matrix with REE data |
... |
further parameters of the function |
tetradAnenburg
is merely a wrapper for the function lambda.tetrad.fit
with
arguments fitt1, fitt2, fitt3, fitt4
set to TRUE
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
When reporting results, also state which fitting settings were used as they will often change the coefficient values. Please cite Anenburg & Williams (2022) when using this in your work.
Michael Anenburg, Michael.Anenburg@anu.edu.au
wrapper function for GCDkit: Vojtěch Janoušek, vojtech.janousek@geology.cz
Anenburg M (2020) Rare earth mineral diversity controlled by REE pattern shapes. Min Mag 85:629-639 doi: 10.1180/mgm.2020.70
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
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") tetradAnenburg(WR[,REE], cean = FALSE, euan = TRUE)