Feb., 1949 NOTES 743 decay of potassium-40 in the existing minerals

Granite gneiss. Sudbury, Ont. 0.51 X decay of potassium-40 in the existing minerals. (4) A careful isotopic analysis would be required to establish th...
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NOTES

Feb., 1949

743

TABLE I COMPARISON O F AGEWITH Description of sample

Quartz, Cornucopia formation Soda feldspar

Location from which obtained

Cornucopia, N. E. Oregon

Ohanepecosh Hot Springs, Washington Potash feldspar, Cornucopia, N. E. Oregon Cornucopia formation Bostonite Marblehead, Massachusetts Granite, Silver Silver Plume, Colorado Plume Formation Granite Sudbury, Ont. Granite gneiss

Sudbury, Ont.

THE He cc./g.'at S. T.P.

RATIOA/K

IN

A cc./gI a t S. T.P.

ROCKS K, %

G. ats, A G. ats. K

Approximate age in millions of years

0,027 8.4 x 10-4 10-4

0.43

0.19 X lo-*

3.25 X lo-'

12.8

lo-'

0.81 X lo-'

2.08

1.4 X

1.91

100 (Late Mesozoic) 7 . 7 x IO-' 30 (Tertiary) 4.4 x lo-' 100 (Late Mesozoic) 300 6 . 8 X 10-8 (Carboniferous) 1.3 X 10-6 9403

10-4

3.33

2.4

5 . 2 X IO-'

1.05

8 . 6 X 10-6

0,022 X 0.062

x