Table AT1. Algorithms for estimating precursor compositions of altered rocks, based on fractionation trends in fresh Pual Ridge lavas and the assumption of Ti and Zr immobility: X = Zr (ppm)/TiO2 (wt%).
 
Unit
Precursor
composition (y)
Variance
(%)
Oxide:
SiO2 wt% y = 8.23 ln(x) + 24.57 1
TiO2 wt% y = 2.63 – 0.385 ln(x) 3
Al2O3 wt% y = 20.54 – 1.23 ln(x) 1
FeO (total) wt% y = 82.1x–0.557 5
MnO wt% y = 0.75x–0.328 5
MgO wt% y = 229x–1.031 24
CaO wt% y = 124x–0.703 5
Na2O wt% y = 0.597ln(x) + 1.82 3
K2O wt% y = 0.121x0.506 4
P2O5 wt% y = 120x–1.30 11
Element:
S (total) wt% y = 10.0x–1.463 177
Li ppm y = 4.64ln(x) – 10.9 12
Be ppm y = 0.321ln(x) – 0.55 13
Sc ppm y = 174x–0.515 7
V ppm y = (5E+06)x–2.32 34
Cr ppm y = 7.72x0.047 148
Co ppm y = 63.3 – 10.8 ln(x) 51
Ni ppm y = 38.4x–0.325 103
Cu ppm y = 275x–0.482 23
Zn ppm y = 190x–0.167 5
Ga ppm y = 41.5x–0.196 15
Ge ppm y = 34.5 – 5.25 ln(x) 76
As ppm y = 2.27x0.154 55
Rb ppm y = 10.6 ln(x) – 32.8 11
Sr ppm y = 2491x–0.420 3
Y ppm y = 10.8x0.191 4
Zr ppm y = 44.0 ln(x) – 116 3
Mo ppm y = 0.728 ln(x) – 2.0 20
Ag ppm y = 9.0 – 1.44 ln(x) 51
Cd ppm y = 0.042 ln(x) + 0.20 44
In ppb y = 71x0.017 19
Sb ppb y = 1364 – 213 ln(x) 86
Te ppb y = 4.70 ln(x) – 8.5 177
Cs ppm y = 0.042x0.563 10
Ba ppm y = 33.2x0.437 6
La ppm y = 4.083 ln(x) – 9.09 9
Ce ppm y = 8.339 ln(x) – 16.05 8
Pr ppm y = 1.115 ln(x) – 1.76 11
Nd ppm y = 3.66 ln(x) – 1.77 8
Sm ppm y = 0.730 ln(x) + 0.61 7
Eu ppm y = 0.0545 ln(x) + 1.16 10
Gd ppm y = 0.621 ln(x) + 1.69 8
Tb ppm y = 0.146 ln(x) + 0.15 12
Dy ppm y = 0.745 ln(x) + 1.59 8
Ho ppm y = 0.215 ln(x) + 0.15 13
Er ppm y = 0.6401 ln(x) + 0.28 8
Tm ppm y = 0.138 ln(x) – 0.13 13
Yb ppm y = 0.889 ln(x) – 0.84 7
Lu ppm y = 0.219 ln(x) – 0.45 12
Tl ppb y = 24.0x0.447 22
Pb ppm y = 1.14x0.309 15
Bi ppb y = 21.2x0.260 90
Th ppb y = 524 ln(x) – 1448 12
U ppb y = 329 ln(x) – 990 12