Table 1 (continued). 40Ar/39Ar Dating of biotites from Leg 165 tephra layers.

Core, section,
interval (cm)
Analysis
number
40Ar/39Ar
38Ar/39Ar
37Ar/39Ar
36Ar/39Ar
39Ar
Atm
(%)
40Ar*/39Ar
Age
(Ma)
±
(m.y.)
wi
xi*wi
Mean
Error
165-999B-                            
7R-CC, 13-14 1 6.865 0.123   0.008 0.0024 64.63 4.44 24.56 9.67 0.01 0.3    
7R-CC, 13-14 2 3.354 0.091   0.000 0.0019 100.00 3.35 18.60 12.15 0.01 0.1    
7R-CC, 13-14 3 5.232 0.182   0.003 0.0116 80.53 4.21 23.34 2.05 0.24 5.6    
7R-CC, 13-14 4 5.558 0.205   0.004 0.0044 76.08 4.23 23.42 5.29 0.04 0.8    
7R-CC, 13-14 5 4.611 0.070   0.000 0.0054 100.00 4.61 25.52 6.77 0.02 0.6    
                          23.44 1.79
15R-2, 45-46 1 5.253 0.117   0.000 0.0042 100.00 5.25 29.05 5.58 0.03 0.9    
15R-2, 45-46 2 5.415 0.110   0.002 0.0059 90.67 4.91 27.17 4.02 0.06 1.7    
15R-2, 45-46 3 5.754 0.126   0.002 0.0189 91.84 5.28 29.22 1.39 0.51 15.0    
15R-2, 45-46 4 4.982 0.111   0.002 0.0046 87.15 4.34 24.04 5.09 0.04 0.9    
15R-2, 45-46 5 5.150 0.111   0.003 0.0116 85.19 4.39 24.29 2.04 0.24 5.8    
15R-2, 45-46 6 5.150 0.112   0.000 0.0075 100.00 5.15 28.49 3.13 0.10 2.9    
15R-2, 45-46 7 5.150 0.113   0.000 0.0124 100.00 5.15 28.48 1.44 0.48 13.7    
15R-2, 45-46 8 4.940 0.119   0.004 0.0089 73.25 3.62 20.06 2.65 0.14 2.8    
                          27.21 0.79
47R-6, 4-5 1 16.275 0.057   0.000 0.0006 100.00 16.27 88.52 38.59 0.00 0.1    
47R-6, 4-5 2 10.245 0.040   0.005 0.0037 84.33 8.64 47.53 6.34 0.02 1.2    
                          48.61 1.15
48R-3, 6-7 1 10.377 0.109   0.002 0.0048 94.07 9.76 53.62 4.94 0.04 2.2    
48R-3, 6-7 2 9.351 0.106   0.000 0.0091 100.00 9.35 51.39 2.71 0.14 7.0    
48R-3, 6-7 3 9.728 0.107   0.000 0.0081 100.00 9.73 53.43 4.49 0.05 2.7    
48R-3, 6-7 4 9.686 0.101   0.000 0.0039 100.00 9.69 53.20 6.12 0.03 1.4    
48R-3, 6-7 5 9.149 0.106   0.000 0.0036 100.00 9.15 50.29 6.48 0.02 1.2    
48R-3, 6-7 6 9.744 0.111   0.002 0.0042 92.86 9.05 49.75 8.52 0.01 0.7    
48R-3, 6-7 7 10.040 0.107   0.000 0.0031 100.00 10.04 55.12 7.61 0.02 1.0    
48R-3, 6-7 8 14.070 0.104   0.014 0.0035 70.41 9.91 54.40 6.56 0.02 1.3    
48R-3, 6-7 9 9.966 0.099   0.001 0.0190 96.88 9.66 53.04 1.67 0.36 19.0    
48R-3, 6-7 10 9.473 0.101   0.003 0.0034 90.75 8.60 47.30 6.99 0.02 1.0    
48R-3, 6-7 11 9.832 0.108   0.000 0.0103 100.00 9.83 54.00 2.64 0.14 7.7    
48R-3, 6-7 12 9.429 0.108   0.000 0.0048 100.00 9.43 51.81 5.07 0.04 2.0    
48R-3, 6-7 13 12.003 0.101   0.000 0.0047 100.00 12.00 65.70 5.35 0.03 2.3    
48R-3, 6-7 14 9.617 0.101   0.001 0.0075 95.90 9.22 50.69 3.23 0.10 4.9    
48R-3, 6-7 15 10.489 0.099   0.004 0.0023 87.72 9.20 50.58 10.15 0.01 0.5    
48R-3, 6-7 16 9.607 0.089   0.005 0.0021 85.35 8.20 45.14 11.66 0.01 0.3    
48R-3, 6-7 17 10.351 0.101   0.003 0.0063 90.96 9.42 51.74 3.73 0.07 3.7    
48R-3, 6-7 18 9.030 0.096   0.004 0.0048 86.37 7.80 42.96 4.90 0.04 1.8    
48R-3, 6-7 19 9.706 0.089   0.000 0.0028 100.00 9.71 53.31 8.43 0.01 0.7    
48R-3, 6-7 20 8.934 0.086   0.000 0.0026 100.00 8.93 49.13 8.86 0.01 0.6    
                          52.47 0.92
165-1000A-                            
16H-6, 21-22 1 2.252 0.104 -0.002 0.002 32.38 74.48 1.678 8.94 0.86 1.35 12.0    
16H-6, 21-22 2 2.028 0.088 -0.001 0.005 48.24 30.22 0.613 3.27 0.43 5.30 17.3    
16H-6, 21-22 3 3.424 0.096 -0.003 0.002 12.55 82.67 2.83 15.05 1.55 0.41 6.2    
16H-6, 21-22 4 2.071 0.103 0.001 0.004 50.05 36.53 0.756 4.04 0.38 6.83 27.6    
16H-6, 21-22 5 1.362 0.096 -0.003 0.000 29.81 93.89 1.279 6.82 0.68 2.18 14.9    
16H-6, 21-22 6 0.884 0.100 0.000 0.000 19.37 85.51 0.756 4.03 0.98 1.04 4.2    
                          4.80 0.24
28H-1, 88-89 1 1.382 0.083 0.006 0.000 66.03 94.56 1.307 6.96 0.30 11.05 77.0    
28H-1, 88-89 2 1.452 0.088 0.006 0.000 64.36 94.69 1.375 7.33 0.30 11.41 83.6    
28H-1, 88-89 3 1.591 0.089 0.006 0.000 63.82 95.11 1.513 8.06 0.32 9.72 78.4    
28H-1, 88-89 4 1.364 0.085 0.027 0.001 18.03 69.71 0.950 5.07 1.03 0.95 4.8    
28H-1, 88-89 5 1.565 0.082 0.002 0.000 66.53 97.62 1.528 8.14 0.44 5.07 41.3    
                          7.46 0.16
165-1000B-                            
14R-2, 139-140 1 3.695 0.107 0.011 0.001 27.20 95.06 3.512 18.66 0.76 1.73 32.2    
14R-2, 139-140 2 3.471 0.100 0.000 0.000 25.02 97.14 3.371 17.91 0.80 1.57 28.1    
14R-2, 139-140 3 4.342 0.108 0.007 0.004 15.87 72.99 3.169 16.85 1.21 0.69 11.6    
14R-2, 139-140 4 3.634 0.109 0.006 0.000 33.85 97.98 3.561 18.92 0.69 2.12 40.2    
14R-2, 139-140 5 3.555 0.112 0.006 0.000 29.38 97.62 3.470 18.44 0.72 1.92 35.4    
14R-2, 139-140 6 3.451 0.095 0.004 0.000 29.10 97.53 3.366 17.89 0.89 1.26 22.5    
                          18.31 0.33
16R-5, 84-85 1 3.391 0.108 -0.002 0.000 57.97 98.74 3.348 17.79 0.53 3.59 63.9    
16R-5, 84-85 2 3.583 0.078 0.000 0.000 50.61 98.63 3.534 18.77 0.48 4.37 82.1    
16R-5, 84-85 3 3.546 0.090 0.001 0.000 62.65 98.88 3.506 18.63 0.43 5.53 103.1    
16R-5, 84-85 4 3.357 0.088 0.001 0.000 115.30 99.36 3.336 17.73 0.75 1.77 31.3    
16R-5, 84-85 5 3.196 0.163 0.002 0.000 74.19 98.95 3.162 16.81 0.35 8.15 136.9    
16R-5, 84-85 6 3.256 0.082 0.002 0.000 76.82 99.01 3.224 17.14 0.33 9.39 161.0    
16R-5, 84-85 7 3.212 0.108 0.002 0.000 100.83 99.23 3.188 16.94 0.93 1.14 19.4    
16R-5, 84-85 8 3.282 0.095 0.005 0.000 61.53 98.77 3.241 17.23 0.35 8.29 142.7    
16R-5, 84-85 9 3.300 0.103 0.008 0.000 37.29 97.98 3.233 17.18 0.52 3.71 63.7    
                          17.50 0.15
19R-2, 99-101 1 3.284 0.209 0.007 0.000 55.55 98.64 3.239 17.22 0.74 1.81 31.2    
19R-2, 99-101 2 3.088 0.211 0.009 0.000 35.90 97.76 3.019 16.05 0.67 2.20 35.4    
19R-2, 99-101 3 3.443 0.223 0.005 0.000 42.97 98.32 3.385 17.99 0.48 4.38 78.8    
19R-2, 99-101 4 3.152 0.219 0.016 0.000 20.34 96.13 3.030 16.11 0.97 1.06 17.0    
19R-2, 99-101 5 3.184 0.219 0.007 0.000 38.88 97.99 3.120 16.59 0.60 2.73 45.3    
19R-2, 99-101 6 3.534 0.213 -0.002 0.000 49.66 98.59 3.484 18.51 0.50 3.95 73.1    
19R-2, 99-101 7 3.557 0.218 0.001 0.000 42.45 98.36 3.499 18.59 0.86 1.35 25.2    
19R-2, 99-101 8 3.459 0.211 0.008 0.000 33.95 97.89 3.386 17.99 0.65 2.40 43.2    
19R-2, 99-101 9 3.665 0.217 0.003 0.005 44.68 62.11 2.28 12.12 0.44 5.14 62.2    
19R-2, 99-101 10 3.520 0.211 0.001 0.000 114.99 99.39 3.498 18.59 0.55 3.25 60.5    
19R-2, 99-101 11 3.320 0.212 0.002 0.000 92.22 99.19 3.293 17.50 0.68 2.19 38.4    
19R-2, 99-101 12 3.618 0.219 0.003 0.000 75.98 99.10 3.586 19.05 0.76 1.73 33.0    
19R-2, 99-101 13 3.629 0.209 0.001 0.000 91.31 99.25 3.602 19.13 0.66 2.27 43.5    
                          17.02 0.17
165-1001A-                            
26R-2, 63-64 1 12.237 0.078 -0.018 0.001 7.62 97.34 11.911 62.51 3.12 0.10 6.4    
26R-2, 63-64 2 12.007 0.079 -0.008 0.002 15.63 96.03 11.530 60.55 1.98 0.25 15.4    
26R-2, 63-64 3 10.605 0.085 0.009 0.002 4.30 94.56 10.028 52.77 4.59 0.05 2.5    
                          60.14 1.57
36R-3, 70-71 1 21.041 0.094 -0.008 0.015 12.24 78.31 16.48 85.91 3.01 0.11 9.5    
36R-3, 70-71 2 19.788 0.104 -0.001 0.016 27.33 75.67 14.974 78.24 2.25 0.20 15.5    
36R-3, 70-71 3 23.395 0.120 -0.001 0.028 11.63 64.42 15.072 78.74 2.51 0.16 12.5    
36R-3, 70-71 4 20.707 0.108 0.008 0.016 22.07 77.19 15.983 83.39 1.95 0.26 21.8    
36R-3, 70-71 5 19.749 0.100 0.017 0.017 14.72 73.96 14.607 76.36 1.76 0.32 24.7    
36R-3, 70-71 6 16.086 0.119 0.018 0.012 12.90 77.27 12.429 65.18 2.00 0.25 16.2    
36R-3, 70-71 7 19.251 0.119 0.025 0.016 12.76 75.74 14.582 76.23 2.29 0.19 14.5    
36R-3, 70-71 8 16.926 0.091 0.009 0.012 39.39 79.71 13.492 70.65 1.14 0.77 54.7    
                          74.78 0.66
165-1001B-                            
6R-3, 130-131 1 15.762 0.192 0.024 0.001 6.28 97.49 15.366 80.25 3.45 0.08 6.8    
6R-3, 130-131 2 16.520 0.189 0.058 0.002 3.88 96.13 15.880 82.87 5.22 0.04 3.0    
                          81.04 2.88

Notes: %Atm = 100*[(40Ar/39Ar-295.5*36Ar/39Ar)/40Ar/39Ar]. 40Ar*/39Ar = the ratio of the radiogenic isotope of argon (40Ar) to the 39Ar produced in the reactor from potassium. wi = the weighting used in the weighted mean and is the inverse of variance on each measurement. xi*wi = the weighting multiplied by the measured age of each measurement.