zrSaturation {GCDkit} | R Documentation |
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.
zrSaturation(cats = milli, T = 0, Zr = filterOut(WR, "Zr", 1))
cats |
numeric matrix; whole-rock data recast to millications |
T |
assumed temperature of the magma in °C |
Zr |
numeric vector with Zr concentrations |
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
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 |
Saturation.r
Vojtěch Janoušek, vojtech.janousek@geology.cz
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
data(sazava) accessVar("sazava") zrSaturation(T=800)