Sample ID (rock unit)

Dated Mineral/s

K, % ± σ

⁴⁰Ar rad, (ng/g)

% ⁴⁰Ar air

Age (Ma)

Error 2σ

COO-01 (andesite porphyry)

Feldspar concentrate

3.59 ± 0.4

7.17 ± 0.07

39.5

28.6

0.9

COO-04 (polymictic diatreme breccia)

Feldspar concentrate

0.682 ± 0.015

1.51 ± 0.03

68.6

31.7

1.9