zrSaturation {GCDkit}R Documentation

Zircon saturation (Watson + Harrison 1983, Boehnke et al. 2013)

Description

Calculates zircon saturation temperatures for the observed major-element data and Zr concentrations. Returns also Zr saturation levels for the given major-element compositions and assumed magma temperature.

Usage

zrSaturation(cats = milli, T = 0, Zr = filterOut(WR, "Zr", 1))

Arguments

cats

numeric matrix; whole-rock data recast to millications

T

assumed temperature of the magma in °C

Zr

numeric vector with Zr concentrations

Details

Calculates Zr saturation concentration at a given temperature. Given 'T' is the estimated absolute temperature (K) of the magma and 'M' is a cationic ratio:

M = 100(Na + K + 2Ca)/(Al*Si)

it can be written (Watson & Harrison 1983):

DZr = exp(-3.8 - 0.85(M - 1) + 12900/T)

The Zr saturation level is then given by:

Zr.sat = 497644/DZr

On the other hand, the saturation temperature can be obtained from the observed Zr concentration and magma composition (assuming no zircon inheritance)

DZr = 497644/Zr

TZr.sat.C = 12900/(ln(DZr) + 3.8 + 0.85(M - 1)) - 273.15

This model has been reformulated by Kelsey et al. (2008) as follows:

DZr = exp(11574/T-0.679FM-1.7965)

using the cationic ratio 'FM'

M = (Na + K + 2(Ca + Fe + Mg))/(Al*Si)

Utilizing the model of Kelsey et al. (2008), the zircon saturation temperature can be calculated as:

TZr.sat.C = 11574/(ln(497644/Zr.sat)+0.679FM+1.7965) - 273.15

A re-calibration of the (Watson & Harrison 1983) model by Boehnke et al. (2013) has yielded:

DZr = exp(10108/T - 1.16(M - 1) - 1.48)

and

TZr.sat.C = 10108/(ln(497644/Zr) + 1.16(M - 1) + 1.48) - 273.15

Value

Returns a matrix 'results' with the following columns:

M

cationic ratios

Zr

observed Zr concentrations

Zr.sat

saturation levels of Zr after Watson & Harrison (1983) for assumed temperature

TZr.sat.C

zircon saturation temperatures after Watson & Harrison (1983) in °C

Zr.sat (Boehnke)

saturation levels of Zr after Boehnke et al. (2013) for assumed temperature

TZr.sat.C (Boehnke)

zircon saturation temperatures after Boehnke et al. (2013) in °C

Plugin

Saturation.r

Author(s)

Vojtěch Janoušek, vojtech.janousek@geology.cz

References

Boehnke P, Watson EB, Trail D, Harrison TM, Schmitt AK (2013) Zircon saturation re-revisited. Chem Geol 351: 324-334 doi: 10.1016/j.chemgeo.2013.05.028

Kelsey DE, Clark C, Hand M (2008) Thermobarometric modelling of zircon and monazite growth in melt-bearing systems: examples using model metapelitic and metapsammitic granulites. J Metamorph Geol 26: 199-212 doi: 10.1111/j.1525-1314.2007.00757.x

Watson EB & Harrison M (1983) Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types. Earth Planet Sci Lett 64: 295-304 doi: 10.1016/0012-821X(83)90211-X

Examples

    data(sazava)
    accessVar("sazava")

    zrSaturation(T=800)

[Package GCDkit version 6.1 Index]