95-6-11(3) K-feldspar (J = 0.00866) Total gas age = 31.33 ± 0.26 Ma

step

T

(°C)

⁴⁰Ar/³⁹Ar

³⁷Ar/³⁹Ar

³⁶Ar/³⁹Ar

³⁹Ar

(mol)

S³⁹Ar

(%)

⁴⁰Ar*

(%)

Age ± 1s

(Ma)

1

450

101.8

3.98E-02

2.89E-01

5.98E-15

0.21

16.1

239.5 ± 6.4

2

500

4.831

2.53E-02

1.01E-02

1.37E-14

0.70

37.6

28.2 ± 0.8

3

500

3.234

2.70E-02

5.91E-03

4.95E-15

0.88

45.3

22.7 ± 2.4

4

550

2.419

3.80E-02

2.62E-03

1.66E-14

1.47

67.1

25.2 ± 0.7

5

550

2.213

4.12E-02

2.25E-03

1.36E-14

1.96

68.9

23.7 ± 0.7

6

600

2.109

3.84E-02

1.30E-03

5.08E-14

3.78

80.8

26.4 ± 0.2

7

600

2.057

2.60E-02

1.40E-03

7.58E-14

6.49

78.8

25.2 ± 0.1

8

650

1.886

3.55E-02

4.79E-04

4.99E-14

8.27

91.3

26.7 ± 0.2

9

700

1.961

3.45E-02

4.04E-04

1.15E-13

12.4

92.8

28.2 ± 0.1

10

750

1.932

2.61E-02

2.78E-04

1.60E-13

18.1

94.6

28.3 ± 0.1

11

800

1.935

2.31E-02

2.54E-04

1.41E-13

23.1

94.9

28.5 ± 0.1

12

850

1.964

1.76E-02

3.50E-04

1.42E-13

28.2

93.5

28.5 ± 0.1

13

900

2.055

1.58E-02

6.47E-04

9.25E-14

31.5

89.5

28.5 ± 0.1

14

950

2.106

1.59E-02

8.45E-04

1.40E-13

36.5

87.0

28.4 ± 0.1

15

1000

2.317

2.28E-02

1.47E-03

8.93E-14

39.7

80.3

28.8 ± 0.1

16

1050

2.736

2.00E-02

2.76E-03

1.42E-13

44.8

69.3

29.4 ± 0.1

17

1100

2.940

2.42E-02

3.16E-03

1.93E-13

51.7

67.4

30.7 ± 0.2

18

1130

3.289

2.94E-02

4.20E-03

2.16E-13

59.4

61.6

31.4 ± 0.1

19

1160

2.959

2.38E-02

2.93E-03

3.09E-13

70.5

70.0

32.1 ± 0.1

20

1190

2.629

1.54E-02

1.85E-03

2.79E-13

80.4

78.3

31.9 ± 0.1

21

1220

2.502

1.26E-02

1.44E-03

2.82E-13

90.5

82.0

31.8 ± 0.1

22

1350

2.724

3.09E-02

2.14E-03

2.65E-13

100

76.0

32.1 ± 0.1