OConnor {GCDkit}R Documentation

Classification diagram for siliceous igneous rocks, based on Fsp composition (O'Connor 1965)

Description

Assigns data for O'Connor's triangular diagram into Figaro template (list 'sheet') and appropriate values into 'x.data' and 'y.data'.

Usage

OConnorVolc()

OConnorPlut()

Details

The O'Connor's triangular diagram is based on combination of Albite, Anorthite and K-feldspar modal or normative data. While the function 'OConnorPlut' can plot either modal or normative diagrams for plutonic rocks, 'OConnorVolc' is to be used exclusively with normative data computed from chemical compositions of volcanic rocks.

OConnorVolc.png

In fact, the triangle represents projection of the Quartz - K-feldspar - Albite - Anorthite tetrahedron. All three diagrams are designed for quartz-rich rocks, i.e. those with quartz contents higher than 10 such silica-rich samples, the rock type can be determined purely on the basis of the feldspars' proportions.

OConnorPlut.png

As the specific version of the normative calculation is not mentioned in the original paper by 'O'Connor (1965)', the function 'CIPW', designed after 'Hutchison (1974, 1975)' was implemented.

Value

sheet

list with Figaro Style Sheet data

x.data, y.data

An, Ab and Or data (see details) transformed to orthogonal coordinates

Author(s)

Vojtech Erban, vojtech.erban@geology.cz

References

O'Connor J T (1965) A classification for Quartz-rich igneous rocks based on feldspar ratios. U.S. Geol. Survey Prof Paper 525-B: B79-B84

Hutchison C S (1974) Laboratory Handbook of Petrographic Techniques. John Wiley & Sons, New York, p. 1-527

Hutchison C S (1975) The norm, its variations, their calculation and relationships. Schweiz Mineral Petrogr Mitt 55: 243-256

See Also

classify figaro CIPW plotDiagram

Examples

plotDiagram("OConnorVolc", FALSE)

classify("OConnorVolc")

[Package GCDkit version 4.0 Index]