Agrawal {GCDkit}R Documentation

Trace-element based discrimination plots for (ultra-)basic rocks (Agrawal et al. 2008)

Description

Plots data stored in 'WR' into discrimination plots proposed by Agrawal et al. (2008) for (ultra-) basic rocks (SiO2 < 52 wt. %).

Usage

    Agrawal(plot.txt = getOption("gcd.plot.text"),GUI=FALSE)

Arguments

plot.txt

logical, annotate fields by their names?

GUI

logical, is the function called from a GUI?

Details

Suite of five diagrams for discrimination of geotectonic environment of ultrabasic and basic rocks, proposed by Agrawal et al. (2008). It is based on linear discriminant analysis applied to log-transformed concentration ratios of five trace elements (La, Sm, Yb, Nb, and Th), i.e., using four ratios ln(La/Th), ln(Sm/Th), ln(Yb/Th), and ln(Nb/Th). The two discriminant functions, DF1 and DF2, are mathematically designed to maximize the separation between the groups and account for 100 percent of the variance in the data.

Note that only samples with SiO2 < 52 wt. % are plotted.

Also note that each diagram applies only to environments explicitly mentioned. Samples from the environment not taken into account will be misinterpreted (the CRB + OIB + MORB diagram is not designed for IAB etc.) See the Agrawal et al (2008) for further details.

Following geotectonic settings may be deduced:

Abbreviation used Environment
IAB island arc basic rocks
CRB continental rift basic rocks
OIB ocean-island basic rocks
MORB mid-ocean ridge basic rocks

Agrawal.png

Value

None.

Note

This function uses the plates concept. The individual plots can be selected and their properties/appearance changed as if they were stand alone Figaro-compatible plots.

See Plate, Plate editing and figaro for details.

Author(s)

Vojtěch Janoušek, vojtech.janousek@geology.cz

References

Agrawal S, Guevara M, Verma S (2008) Tectonic discrimination of basic and ultrabasic volcanic rocks through log-transformed ratios of immobile trace elements. Int Geol Review 50: 1057-1079 doi: 10.2747/0020-6814.50.12.1057

See Also

Verma, Plate, Plate editing, plotPlate, figaro

Examples

    data(blatna)
    accessVar("blatna")

    # plot the diagrams
    plotPlate("Agrawal")

[Package GCDkit version 6.1 Index]