TAS {GCDkit}R Documentation

IUGS recommended TAS (Le Bas et al. 1986)

Description

Assigns data for IUGS recommended TAS diagram into Figaro template (list 'sheet') and appropriate values into 'x.data' and 'y.data'

Usage

TAS(cutoff=95)

Arguments

cutoff

numeric; the minimal sum of the analysis to be considered for classification

Details

TAS diagram, as proposed by Le Bas et al. (1986), codified by Le Maitre et al. (1989) and slightly modified by Le Bas (2000).

TAS.png

The diagram (in its basic form) defines following fields:

foidite
picrobasalt
basalt
basaltic andesite
andesite
dacite
rhyolite
trachybasalt
basaltic trachyandesite
trachyandesite
trachyte/trachydacite
tephrite/basanite
phonotephrite
tephriphonolite
phonolite

This primary division is further enhanced by the 'TASadd' routine (called automatically by 'classify').

Following actions are carried out:

Note that systematics of high-Mg rocks follows revised IUGS Recommendations (Le Bas et al., 2000; Le Maitre et al. 2002) which differ from their 1st edition (Le Maitre et al. 1989). Further subdivisions recommended by Le Maitre et al. (1989) are not implemented in GCDkit, mainly for poorly defined CIPW version used by the Subcommission.

The boundary between the subalkaline and alkaline domains is based on (Irvine & Baragar 1971).

Value

x.data

SiO2 data recast to anhydrous sum (matrix 'WRanh')

y.data

Na2O+K2O data recast to anhydrous sum (matrix 'WRanh')

sheet

list with Figaro Style Sheet data

results

matrix with classification results

groups

vector with classification results

grouping

set to -1

Warning

Note that, in accordance with the IUGS recommendation, the diagram is based on analyses recalculated on volatile-free basis.

Author(s)

Vojtěch Erban, erban@sopky.cz
& Vojtěch Janoušek, vojtech.janousek@geology.cz

References

Irvine TN, Baragar WRA (1971) A guide to the chemical classification of the common volcanic rocks. Can J Earth Sci 8:523-548 doi: 10.1139/e71-055

Le Bas MJ, Le Maitre RW, Streckeisen A & Zanettin B (1986) A chemical classification of volcanic rocks based on the total alkali-silica diagram. J Petrology 27: 745-750 doi: 10.1093/petrology/27.3.745

Le Bas MJ (2000) IUGS Reclassification of the High-Mg and Picritic Volcanic Rocks. J Petrology 41: 1467-1470 doi: 10.1093/petrology/41.10.1467

Le Maitre RW (ed) (1989) Igneous Rocks: A Classification and Glossary of Terms, 1st edition. Cambridge University Press

Le Maitre RW (ed) (2002) Igneous rocks: a classification and glossary of terms: recommendations of the International Union of Geological Sciences, Subcommission on the Systematics of Igneous Rocks, 2nd edition. Cambridge University Press

See Also

classify figaro plotDiagram

Examples

    data(atacazo) 
    accessVar("atacazo")
    
    # To plot data stored in WR or its subset (menu Classification)
    plotDiagram("TAS", FALSE)
    
    # To Classify data stored in WR (Groups by diagram)
    classify("TAS")

[Package GCDkit version 6.1 Index]