Schandl {GCDkit}R Documentation

Schandl and Gorton (2002)

Description

Plots data stored in 'WR' (or its subset) into the classification diagrams after Schandl and Gorton (2002).

Usage

Schandl(plot.txt = getOption("gcd.plot.text"))

Arguments

plot.txt

logical, annotate fields by their names?

Details

Suite of four diagrams for geotectonic environment discrimination of felsic volcanic rocks (rhyolites), proposed by Schandl and Gorton (2002). It is based on combination of four presumably little immobile trace elements (namely Ta, Yb, Th, and Hf).

Diagrams were designed to decipher the geotectonic setting of felsic volcanic suites, specifically those associated with the volcanogenic massive sulphide (VMS) deposits.

a) Ta/Yb versus Th/Yb diagram from Gorton and Schandl (2000) is divided into three fields: Oceanic Arcs, Active Continental Margins (ACM) and Within-Plate Volcanic Zones (WPVZ).

The Within-Plate Basalts (WPB) and Mid-Ocean Ridge Basalts (MORB) represent compositions previously determined by Pearce (1982, 1983).

b) Ta vs. Th diagram demonstrates the Th enrichment of felsic volcanic rocks at post-Archaean VMS deposits (and of some unmineralized Archaean rhyolites) with respect to Ta.

c) Graph of Ta/Hf vs Th/Hf ratios shows the similar incompatibility between Th and Ta in two different tectonic environments: Active Continental Margins and Within-Plate Volcanic Zones.

d) Yb vs. Th/Ta diagram with fields for associations of Oceanic Arcs, Active Continental Margins, Within Plate Volcanic Zones and MORB.

Taken together, the following geotectonic settings may be deduced:

Rock Association

Abbreviation

Oceanic Arcs

Active Continental Margins

ACM

Within-Plate Volcanic Zones

WPVZ

Further abbreviations used on the plots:

Rock Association

Abbreviation

Mid-Oceanic Ridge Basalts

MORB

Within-Plate Basalts

WPB

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)

Vojtech Janousek, vojtech.janousek@geology.cz

References

Gorton M P & Schandl E S (2000) From continents to island arcs: A geochemical index of tectonic setting for arc-related and within-plate felsic to intermediate volcanic rocks. Can Min 38: 1065-1073. doi: 10.2113/gscanmin.38.5.1065

Pearce J A (1982) Trace element characteristics of lavas from destructive plate boundaries. In Thorpe R S (ed) Andesites: Orogenic Andesites and Related Rocks. John Wiley, Chichester, pp 525-548.

Pearce J A (1983) Role of the sub-continental lithosphere in magma genesis at active continental margins. In Hawkesworth C J & Norry M J (eds) Continental Basalts and Mantle Xenoliths. Shiva, Nantwich. pp 230-249

Schandl E S & Gorton M P (2002) Application of high field strength elements to discriminate tectonic settings in VMS environments. Economic Geology 97: 629-642. doi: 10.2113/97.3.629

See Also

Plate, Plate editing, plotPlate, figaro

Examples

#plot the diagrams
plotPlate("Schandl")

[Package GCDkit version 3.00 Index]