254 / 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
A456 49847 267 104 0.92 0.0 5.797 1.1 0.3362 0.8 0.74 0.1251 0.7 1868 13 1946 10 2030 13 92
A537 11375 57 24 1.04 0.0 5.906 1.5 0.3458 0.7 0.49 0.1239 1.3 1914 12 1962 13 2013 23 95
A541 15947 76 31 0.89 0.7 6.022 2.0 0.3559 0.9 0.42 0.1227 1.9 1963 14 1979 18 1996 33 98
A481
5905 28 12 1.12 0.7 6.058 3.3 0.3583 1.0 0.31 0.1226 3.1 1974 18 1984 29 1995 56 99
A423 14591 60 25 0.48 3.9 6.059 3.0 0.3571 1.0 0.32 0.1231 2.8 1968 16 1984 26 2001 50 98
A401 10229 22 9 0.85 b.d.
6.091 1.7 0.3419 1.0 0.60 0.1292 1.4 1896 17 1989 15 2087 24 91
A428 23145 114 56 2.07 0.0 6.110 1.4 0.3436 0.9 0.65 0.1290 1.1 1904 15 1992 13 2084 19 91
A437 18057 100 43 1.15 0.0 6.155 1.2 0.3597 0.8 0.62 0.1241 1.0 1981 13 1998 11 2016 17 98
A465 13581 72 29 0.81 b.d.
6.165 1.3 0.3569 0.7 0.56 0.1253 1.1 1968 12 2000 11 2033 19 97
A536
6838 14 5 0.57 0.1 6.167 1.6 0.3483 0.9 0.54 0.1284 1.4 1927 15 2000 14 2076 24 93
A403 47995 236 87 0.30 0.1 6.180 1.0 0.3540 0.7 0.70 0.1266 0.7 1954 12 2002 9 2051 12 95
A444 25503 132 51 0.50 b.d.
6.188 1.3 0.3578 0.8 0.64 0.1254 1.0 1972 14 2003 11 2035 17 97
A512 10375 51 21 0.98 0.1 6.228 1.7 0.3544 0.9 0.50 0.1274 1.5 1956 15 2008 15 2063 26 95
A521 50338 243 88 0.26 0.0 6.233 1.1 0.3525 0.8 0.66 0.1283 0.8 1946 13 2009 10 2074 15 94
A487 14762 75 26 0.00 0.1 6.235 1.5 0.3556 0.8 0.54 0.1271 1.2 1962 14 2009 13 2059 22 95
A395 25194 131 52 0.60 0.0 6.236 1.2 0.3663 0.7 0.59 0.1235 1.0 2012 12 2009 11 2007 17 100
A376 32580 160 61 0.50 b.d.
6.248 1.0 0.3530 0.8 0.76 0.1284 0.7 1949 13 2011 9 2076 11 94
A418 78362 786 332 0.88 0.0 6.255 0.9 0.3670 0.7 0.75 0.1236 0.6 2015 12 2012 8 2009 11 100
A516 10882 52 24 1.37 0.1 6.256 1.8 0.3602 0.9 0.51 0.1260 1.5 1983 16 2012 16 2042 27 97
A414 10356 22 9 0.73 b.d.
6.287 1.5 0.3530 0.8 0.50 0.1292 1.3 1949 13 2017 14 2087 23 93
A433 12852 65 25 0.32 0.8 6.293 2.2 0.3629 1.1 0.47 0.1258 2.0 1996 18 2017 20 2040 35 98
A462 10466 22 9 0.64 0.0 6.325 1.6 0.3501 0.9 0.53 0.1310 1.4 1935 14 2022 14 2112 24 92
A555 47639 470 207 1.02 0.2 6.336 1.3 0.3706 1.0 0.74 0.1240 0.9 2032 17 2023 12 2015 16 101
A560 15419 32 13 0.73 0.1 6.352 1.3 0.3519 0.8 0.62 0.1309 1.0 1944 13 2026 11 2110 17 92
A380
9557 21 13 3.74 0.4 6.367 1.7 0.3658 0.9 0.52 0.1262 1.5 2010 16 2028 15 2046 26 98
A531 12326 24 10 0.99 b.d.
6.381 1.5 0.3550 0.7 0.50 0.1304 1.3 1958 12 2030 13 2103 22 93
A476
9788 20 8 0.73 b.d.
6.388 1.7 0.3593 0.9 0.54 0.1290 1.5 1979 16 2031 15 2084 26 95
A379
7736 39 18 1.60 0.1 6.398 2.1 0.3675 1.3 0.61 0.1263 1.6 2018 22 2032 18 2047 29 99
A378 11308 54 25 1.63 0.0 6.399 1.6 0.3615 1.1 0.67 0.1284 1.2 1989 18 2032 14 2076 21 96
A407
4863 23 9 0.85 0.2 6.401 2.3 0.3587 0.9 0.39 0.1294 2.1 1976 15 2032 21 2090 38 95
A548
5694 26 11 1.02 b.d.
6.405 2.3 0.3574 1.2 0.54 0.1300 1.9 1970 21 2033 20 2098 34 94
A478 15297 54 26 0.97 5.5 6.406 3.5 0.3646 1.0 0.29 0.1274 3.3 2004 17 2033 31 2063 58 97
A486 10566 54 25 1.49 0.0 6.410 2.0 0.3709 0.8 0.40 0.1253 1.8 2034 14 2034 17 2033 32 100
A502 17072 35 15 1.05 b.d.
6.411 1.4 0.3641 0.8 0.55 0.1277 1.2 2002 13 2034 12 2066 20 97
A373
7688 38 16 0.85 0.0 6.418 2.0 0.3644 1.0 0.48 0.1277 1.7 2003 17 2035 18 2067 31 97
A522 17047 77 35 1.24 0.5 6.441 1.9 0.3665 0.9 0.48 0.1275 1.7 2013 16 2038 17 2064 30 98
A557
5284 10 4 0.80 0.8 6.446 2.2 0.3704 0.9 0.39 0.1262 2.1 2031 15 2039 20 2046 37 99
A558 12587 61 24 0.69 0.1 6.453 1.5 0.3607 0.8 0.55 0.1298 1.3 1985 15 2040 14 2095 23 95
A489 18782 86 38 1.04 0.5 6.470 1.4 0.3721 0.7 0.52 0.1261 1.2 2039 13 2042 13 2044 21 100
A511 25918 112 48 0.95 0.3 6.475 1.5 0.3589 0.8 0.57 0.1308 1.2 1977 14 2042 13 2109 21 94
A482 15100 31 13 0.70 0.0 6.500 1.2 0.3687 0.8 0.65 0.1279 0.9 2023 13 2046 10 2069 16 98
A427 10475 21 9 0.84 0.0 6.520 1.7 0.3671 0.7 0.41 0.1288 1.6 2016 12 2049 15 2082 28 97
A459 12520 60 28 1.40 0.1 6.525 1.6 0.3672 0.9 0.58 0.1289 1.3 2016 16 2049 14 2082 22 97
A546 17319 79 36 1.38 0.0 6.561 1.3 0.3667 0.6 0.46 0.1297 1.2 2014 11 2054 12 2094 21 96
A370 14465 29 12 0.80 0.1 6.561 1.6 0.3658 0.7 0.44 0.1301 1.4 2010 12 2054 14 2099 25 96
A460
9709 48 21 1.03 0.0 6.575 1.9 0.3682 1.0 0.55 0.1295 1.6 2021 18 2056 17 2091 27 97
A371 24855 115 47 0.71 0.0 6.582 1.3 0.3646 0.8 0.57 0.1309 1.1 2004 13 2057 12 2110 19 95
A424 16788 79 34 0.96 b.d.
6.588 1.5 0.3647 1.0 0.64 0.1310 1.2 2004 17 2058 14 2111 21 95
A446 11592 56 27 1.73 0.0 6.588 1.6 0.3711 1.0 0.61 0.1288 1.3 2035 17 2058 14 2081 22 98
A410
8262 39 17 1.13 b.d.
6.597 1.8 0.3690 0.7 0.40 0.1297 1.6 2025 12 2059 16 2093 28 97
A464 18713 86 38 1.05 b.d.
6.598 1.1 0.3733 0.7 0.62 0.1282 0.9 2045 12 2059 10 2073 15 99
A434 14128 71 35 1.70 0.0 6.621 1.5 0.3755 1.0 0.65 0.1279 1.2 2055 17 2062 13 2069 20 99
A491 22709 105 48 1.21 0.1 6.621 1.3 0.3683 0.9 0.68 0.1304 0.9 2021 15 2062 11 2103 17 96
A543
7501 35 15 0.94 b.d.
6.625 1.8 0.3671 0.8 0.46 0.1309 1.6 2016 14 2063 16 2110 27 96
A381 13483 64 28 0.91 0.2 6.625 1.5 0.3704 0.8 0.53 0.1297 1.3 2031 14 2063 14 2094 23 97
A451 21371 123 48 0.53 0.3 6.636 2.6 0.3619 2.2 0.84 0.1330 1.4 1991 38 2064 23 2138 25 93
A539
9170 42 20 1.51 0.4 6.644 2.0 0.3614 1.1 0.55 0.1333 1.6 1989 19 2065 17 2142 28 93
A470 17287 35 15 0.94 0.1 6.734 1.5 0.3760 0.7 0.46 0.1299 1.3 2058 12 2077 13 2096 23 98
A452 13482 28 12 0.78 b.d.
6.752 1.4 0.3733 0.8 0.54 0.1312 1.2 2045 13 2079 13 2114 21 97
A477 55304 269 110 0.57 0.0 6.757 1.1 0.3752 0.7 0.68 0.1306 0.8 2054 13 2080 9 2106 14 98
A532 51719 239 102 0.75 0.1 6.758 1.2 0.3775 0.8 0.64 0.1298 0.9 2065 14 2080 11 2096 16 99
A398
5142 24 10 0.74 0.0 6.781 2.2 0.3713 0.9 0.40 0.1324 2.0 2036 15 2083 20 2131 35 96
A467 14712 70 31 1.01 b.d.
6.807 1.4 0.3825 0.7 0.51 0.1291 1.2 2088 13 2087 12 2086 21 100
A501 15492 30 12 0.65 b.d.
6.824 1.3 0.3801 0.7 0.59 0.1302 1.0 2077 13 2089 11 2101 18 99
238