Table 2. Calculated oxygen isotopic compositions for magmas and fluids in equilibrium with magnetite samples.

Magnetite Sample	Magnetite δ18O (‰)	Theoretical magma δ18O (‰) for fractionation from andesite	Value fit	Theoretical magma δ18O (‰) for fractionation from dacite	Value fit	Theoretical aqueous ore fluid δ18O (‰) for fractionation from high-T fluid	Value fit
KES090081	1.5	5.5	x	5.8	✓	6.7	✓
KES090083B	2.8	6.8	✓	7.1	✓	8.0	✓
KES090088	3.4	7.4	✓	7.7	✓	8.6	✓
KES090069	3.0	7.0	✓	7.3	✓	8.2	✓
KES090071	1.9	5.9	✓	6.2	✓	7.1	✓
KES090086	1.7	5.7	✓	6.0	✓	6.9	✓
KES09008A	1.9	5.9	✓	6.2	✓	7.1	✓
KES090009	2.2	6.2	✓	6.5	✓	7.4	✓
KES090037	1.4	5.4	x	5.7	✓	6.6	✓
KES090039	3.7	7.7	✓	7.9	✓	8.9	✓
KES090044	−0.4	3.6	x	3.9	x	4.8	x
KES090065	1.3	5.3	x	5.6	x	6.5	✓
KES090077	0.2	4.2	x	4.5	x	5.4	x
KES090080	1.1	5.0	x	5.4	x	6.3	✓
KES090011	2.8	6.7	✓	7.1	✓	8.0	✓
KES090030	1.8	5.8	✓	6.1	✓	7.0	✓
KES090012	1.2	5.2	x	5.5	x	6.4	✓
KES090020	1.1	5.0	x	5.4	x	6.3	✓
KES090027	1.2	5.2	x	5.5	x	6.4	✓
KES090072	0.9	4.8	x	5.2	x	6.1	✓
KES090024	1.0	5.0	x	5.3	x	6.2	✓
KES090068	1.2	5.1	x	5.5	x	6.4	✓
KES090070	1.8	5.8	✓	6.1	✓	7.0	✓
KES103011	1.8	5.8	✓	6.1	✓	7.0	✓
KES103016	1.5	5.5	x	5.8	✓	6.7	✓

1. 1000lnα _{(mt−andesite)} = −4.0 ‰, 1000lnα _{(mt−dacite)} = −4.3 ‰, regular range of arc andesites/dacites 5.7 – 8 ‰¹⁸.

2. 1000lnα _{(mt−water 800°C)} = −5.2 ‰, regular range for magmatic waters 6–8‰²⁰,³⁴.

✓ = in equilibrium with magma/magmatic water ; X = not in equilibrium with common magmatic values.