251 / 352
207
Pb
a
U
b
Pb
b
Th
b 206
Pbc
c 207
Pb
d
±2s
206
Pb
d
±2s ȡ
e
207
Pb
d
±2s
206
Pb
f
±2s
207
Pb
f
±2s
207
Pb
f
±2s Conc.
g
(cps) (ppm) (ppm)
U (%)
235
U (%)
238
U (%) (rho)
206
Pb (%)
238
U (Ma)
235
U (Ma)
206
Pb (Ma) (%)
Grain
A224
4477 33 13 1.47 0.0 4.689 2.8 0.3130 1.6 0.56 0.1087 2.3 1755 24 1765 24 1777 42 99
A291 16811 215 80 0.65 0.0 5.558 1.8 0.3403 1.3 0.71 0.1184 1.2 1888 21 1910 15 1933 22 98
A297 19398 105 42 1.15 0.2 5.779 2.0 0.3318 1.5 0.72 0.1263 1.4 1847 24 1943 18 2047 25 90
A167 54040 316 122 0.72 0.0 5.894 1.6 0.3417 1.3 0.84 0.1251 0.8 1895 22 1960 14 2030 15 93
A189
6520 30 14 1.50 b.d.
6.038 2.5 0.3540 1.8 0.71 0.1237 1.8 1954 30 1981 22 2010 31 97
A247 22662 243 97 0.67 0.6 6.134 2.7 0.3540 1.5 0.57 0.1257 2.2 1954 26 1995 23 2038 38 96
A255 58333 330 117 0.15 b.d.
6.156 1.5 0.3562 1.2 0.84 0.1253 0.8 1964 21 1998 13 2034 14 97
A322 21012 110 46 0.99 0.0 6.167 1.6 0.3601 1.3 0.79 0.1242 1.0 1983 22 2000 14 2018 18 98
A265 24111 251 107 1.20 0.0 6.212 1.6 0.3426 1.3 0.79 0.1315 1.0 1899 21 2006 14 2118 17 90
A187 51009 597 232 0.52 0.0 6.216 1.4 0.3594 1.2 0.82 0.1254 0.8 1980 20
2007 13 2035 14 97
A256
9838 52 23 1.18 1.5 6.226 2.5 0.3624 1.4 0.54 0.1246 2.1 1994 23 2008 22 2023 38 99
A166
9073 50 20 0.78 b.d.
6.232 2.1 0.3570 1.4 0.64 0.1266 1.6 1968 23 2009 19 2051 29 96
A191 32824 386 165 1.01 0.0 6.244 1.7 0.3624 1.3 0.77 0.1250 1.1 1994 23 2011 15 2028 19 98
A174 25690 146 69 1.66 0.0 6.251 1.7 0.3573 1.3 0.79 0.1269 1.0 1970 22 2012 15 2055 18 96
A246 46443 515 234 1.43 0.0 6.277 1.5 0.3670 1.2 0.80 0.1240 0.9 2015 21 2015 14 2015 17 100
A169 43086 239 90 0.21 b.d.
6.297 2.0 0.3695 1.7 0.87 0.1236 1.0 2027 30 2018 17 2009 17 101
A317 35705 165 76 1.68 0.4 6.313 1.9 0.3669 1.6 0.85 0.1248 1.0 2015 27 2020 16 2026 17 99
A231 10479 122 57 1.47 0.0 6.382 1.9 0.3670 1.3 0.65 0.1261 1.5 2015 22 2030 17 2045 26 99
A207 27852 310 128 0.83 0.3 6.390 1.7 0.3635 1.4 0.80 0.1275 1.0 1999 24 2031 15 2064 18 97
A316
6651 36 16 1.27 0.0 6.426 2.3 0.3674 1.3 0.57 0.1269 1.9 2017 22 2036 20 2055 33 98
A281 24456 253 107 0.86 0.3 6.428 1.7 0.3688 1.2 0.71 0.1264 1.2 2024 21 2036 15 2049 21 99
A205 24020 134 56 0.84 0.0 6.463 1.8 0.3676 1.3 0.71 0.1275 1.2 2018 22 2041 16 2064 22 98
A326
9966 52 25 1.68 0.4 6.511 2.5 0.3733 1.3 0.51 0.1265 2.2 2045 23 2047 23 2050 39 100
A168
8186 44 19 1.04 b.d.
6.517 2.3 0.3691 1.3 0.56 0.1281 1.9 2025 23 2048 20 2072 33 98
A282 15710 165 72 0.88 0.0 6.556 1.8 0.3740 1.3 0.74 0.1271 1.2 2048 23 2053 16 2059 21 99
A209 30385 168 69 0.76 0.0 6.558 1.6 0.3606 1.2 0.77 0.1319 1.0 1985 20 2054 14 2123 18 93
A192
7435 82 37 1.32 0.0 6.588 2.2 0.3654 1.5 0.68 0.1308 1.6 2008 26 2058 20 2109 29 95
A182
6713 38 16 0.91 0.0 6.599 2.2 0.3722 1.4 0.65 0.1286 1.7 2040 25 2059 19 2079 29 98
A275 14429 75 34 1.21 0.0 6.611 2.1 0.3647 1.2 0.57 0.1315 1.7 2004 21 2061 19 2118 30 95
A335
7684 81 35 0.92 0.0 6.613 2.1 0.3766 1.7 0.81 0.1273 1.2 2061 30 2061 18 2062 21 100
A245
9736 100 45 1.10 0.0 6.617 2.2 0.3702 1.5 0.69 0.1296 1.6 2030 27 2062 20 2093 29 97
A341
8955 45 19 0.78 0.0 6.620 1.9 0.3696 1.3 0.68 0.1299 1.4 2027 22 2062 17 2097 24 97
A208
8955 48 19 0.57 b.d.
6.639 2.4 0.3699 1.3 0.55 0.1302 2.0 2029 23 2065 21 2100 35 97
A223
2761 15 6 0.92 0.0 6.642 3.8 0.3658 1.6 0.42 0.1317 3.4 2010 27 2065 34 2121 60 95
A289
4023 21 9 0.92 0.0 6.647 2.7 0.3765 1.6 0.59 0.1281 2.2 2060 28 2066 24 2071 38 99
A273
9825 105 50 1.52 0.0 6.661 1.9 0.3778 1.4 0.73 0.1279 1.3 2066 25 2067 17 2069 24 100
A186
9981 109 50 1.18 0.0 6.679 2.1 0.3747 1.5 0.75 0.1293 1.4 2051 27 2070 18 2088 24 98
A262 32363 350 179 2.02 0.0 6.683 1.7 0.3716 1.3 0.75 0.1304 1.1 2037 22 2070 15 2104 19 97
A342 28468 281 133 1.42 0.0 6.688 1.5 0.3755 1.2 0.79 0.1292 0.9 2055 21 2071 13 2087 16 98
A229 22815 114 50 1.03 0.0 6.693 1.7 0.3722 1.4 0.79 0.1304 1.0 2040 24 2072 15 2103 18 97
A219 13619 33 14 0.99 b.d.
6.709 2.0 0.3730 1.3 0.68 0.1305 1.5 2043 24 2074 18 2104 26 97
A338 20982 205 86 0.73 0.3 6.709 1.6 0.3736 1.3 0.81 0.1302 0.9 2046 23 2074 14 2101 17 97
A343 105551 1062 415 0.31 0.1 6.714 1.5 0.3783 1.3 0.87 0.1287 0.7 2068 23 2074 13 2081 13 99
A250 34790 342 153 1.03 0.2 6.729 1.8 0.3776 1.3 0.71 0.1293 1.3 2065 23 2077 16 2088 22 99
A220 18386 97 46 1.36 0.0 6.740 1.5 0.3786 1.3 0.84 0.1291 0.8 2070 23 2078 14 2086 15 99
A333 43948 226 101 1.07 0.0 6.769 1.8 0.3809 1.6 0.88 0.1289 0.9 2081 28 2082 16 2083 15 100
A206 17710 91 40 0.94 0.0 6.844 2.0 0.3801 1.5 0.73 0.1306 1.4 2077 26 2091 18 2106 24 99
A171
10015 53 24 1.02 0
.0 6.853 2.2 0.3756 1.5 0.67 0.1323 1.6 2056 26 2093 20 2129 29 97
A183
4908 26 11 0.88 0.0 6.854 2.2 0.3821 1.4 0.64 0.1301 1.7 2086 25 2093 19 2099 29 99
A300 15449 79 35 0.97 0.0 6.860 1.7 0.3832 1.2 0.73 0.1298 1.1 2091 22 2093 15 2096 20 100
A277 23561 220 105 1.36 0.0 6.870 1.7 0.3802 1.3 0.81 0.1310 1.0 2077 24 2095 15 2112 17 98
A185
2947 15 7 0.65 b.d.
6.875 3.0 0.3917 1.7 0.57 0.1273 2.5 2131 31 2095 27 2061 43 103
A263 10664 105 45 0.77 b.d.
6.887 2.0 0.3786 1.3 0.68 0.1319 1.4 2070 24 2097 18 2124 25 97
A259 14485 145 61 0.65 0.0 6.889 2.1 0.3839 1.5 0.71 0.1302 1.5 2094 26 2097 19 2100 26 100
A210 10469 52 23 0.82 0.0 6.893 1.9 0.3789 1.3 0.67 0.1319 1.4 2071 23 2098 17 2124 25 98
A177 11994 128 56 0.96 0.0 6.895 2.0 0.3779 1.4 0.67 0.1323 1.5 2067 24 2098 18 2129 26 97
A176
5254 28 13 1.07 0.0 6.897 2.0 0.3816 1.4 0.70 0.1311 1.4 2084 25 2098 18 2112 25 99
A257
7279 77 35 1.04 0.0 6.905 2.1 0.3858 1.4 0.68 0.1298 1.5 2104 25 2099 18 2095 27 100
A226
6431 66 31 1.13 b.d.
6.911 2.1 0.3847 1.3 0.62 0.1303 1.6 2098 23 2100 19 2102 28 100
A248 14330 71 34 1.33 0.0 6.948 1.9 0.3844 1.2 0.62 0.1311 1.5 2097 21 2105 17 2113 26 99
A233 55041 268 114 0.53 0.0 6.963 1.7 0.3899 1.5 0.87 0.1295 0.8 2122 27 2107 15 2091 15 101
A298 15444 75 36 1.31 0.0 6.975 1.6 0.3859 1.2 0.76 0.1311 1.0 2104 22 2108 14 2112 18 100
A319 45770 218 99 1.00 0.0 7.000 1.4 0.3855 1.2 0.87 0.1317 0.7 2102 22 2111 13 2121 12 99
A320 31393 142 61 0.69 0.0 7.042 1.6 0.3797 1.2 0.76 0.1345 1.0 2075 22 2117 14 2158 18 96
235