AFM: A-F-M

In pvermees/GeoplotR: Toolbox for Geological Plots

A-F-M

Description

A-F-M diagram

Usage

AFM(
  A,
  F,
  M,
  genetic = TRUE,
  ternary = TRUE,
  twostage = TRUE,
  kde = TRUE,
  decision = TRUE,
  bty = "n",
  asp = 1,
  xpd = FALSE,
  bw = "nrd0",
  pch = 21,
  bg = NULL,
  dlwd = 1.5,
  dcol = "blue",
  padding = 0.15,
  xlim = NULL,
  ylim = NULL,
  show.labels = FALSE,
  short = TRUE,
  ...
)

Arguments

A	vector with (Na_2O+K_2O) concentrations (in wt%)
F	vector with (FeO + FeO_2O_3) concentrations (in wt%)
M	vector with MgO concentrations (in wt%)
genetic	logical. If TRUE, uses the logratio fit of Vermeesch and Pease (2021). Otherwise uses the empirical fit of Irvine and Baragar (1971).
ternary	logical. If FALSE, produces a logratio plot.
twostage	logical. If TRUE, applies the two-stage magma evolution model of Vermeesch and Pease (2021). Otherwise applies the single stage model. Only used if genetic=TRUE.
kde	logical. If TRUE, adds a kernel density estimate of the Bowen-Fenner indices on a radial scale. Not used if ternary=FALSE.
decision	logical. If TRUE, adds the decision boundary between the tholeiitic and calc-alkaline magma series to the plot.
bty	A character string that determines the type of ‘box’ which is drawn about plots. See par.
asp	the y/x aspect ratio, see plot.window.
xpd	clip the plot region? See par for further details.
bw	the smoothing bandwidth to be used for the kernel density estimate. See density.
pch	plotting character. See the documentation of points() for details.
bg	background colour for the plot symbols. If NULL, uses the assigned classes.
dlwd	line width of the decision boundary.
dcol	colour of the decision boundary.
padding	fractional measure of distance between the data and the kernel density estimate.
xlim	the x axis limits of the plot (see plot.default for details).
ylim	the y axis limits of the plot (see plot.default for details).
show.labels	logical. If TRUE, labels the tholeiitic and calc-alkaline fields.
short	logical. If TRUE, uses abbreviated labels (only used if show.labels is TRUE).
...	additional arguments for the generic points function.

Value

the Bowen-Fenner indices of the samples, where positive values indicate calc-alkaline and negative numbers tholeiitic compositions (Vermeesch and Pease, 2021).

References

Irvine, T. N. and Baragar, W. A guide to the chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8(5):523–548, 1971.

Kuno, H. Differentiation of basalt magmas. Basalts: The Poldervaart treatise on rocks of basaltic composition, pages 623–688, 1968.

Irvine, T.N. and Baragar, W.R.A., 1971. A guide to the chemical classification of the common volcanic rocks. Canadian journal of earth sciences, 8(5), pp.523-548.

Vermeesch, P. and Pease, V. A genetic classification of the tholeiitic and calc-alkaline magma series, Geochemical Perspective Letters.

Examples

data(cath,package='GeoplotR')

A <- cath[,'Na2O']+cath[,'K2O']
F <- cath[,'FeOT']
M <- cath[,'MgO']

# 1. Irvine and Baragar (1971):

AFM(A=A,F=F,M=M,genetic=FALSE,
    bg=cath[,'affinity'],dcol='blue',pch=21)

# 2. Vermeesch and Pease (2021):

oldpar <- par(mfrow=c(2,2),mar=c(4,4,0,0))

tern <- c(TRUE,FALSE,TRUE,FALSE)
stag <- c(TRUE,TRUE,FALSE,FALSE)
for (i in 1:4){
   AFM(A,F,M,ternary=tern[i],decision=TRUE,twostage=stag[i],
       pch=21,bw=0.2,padding=0.15,bg=cath[,'affinity'])
}

par(oldpar)

pvermees/GeoplotR documentation built on Aug. 20, 2024, 4:45 a.m.