Table 1 U–Th isotopic data (±2σ) and activity ratios (232Th/238U), (230Th/238U) and (234U/238U) used for isochron age calculations (see also Supplementary Fig. S3); activity ratios were corrected for mass fractionation and spike contributions; n. d. = not determined; δ234U(0) represents the measured activity ratios at time zero (today) expressed in delta notation (δ234U = [((234U/238U) − 1) ∗ 1,000]).
From: Seep-carbonate lamination controlled by cyclic particle flux
Sample | Weight (mg) | 238U (μg/g) | 232Th (μg/g) | 230Th (pg/g) | 230Th/232Th | Activity ratios | δ234U(0) (‰) | 230Th/U age* (ka) | Isochron age** (ka) | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
(232Th/238U) | (230Th/238U) | (234U/238U) | |||||||||
1 | 15.00 | 2.16 ± 0.01 | 0.234 ± 0.001 | 0.921 ± 0.07 | 3.93 | 0.035 ± 0.001 | 0.026 ± 0.002 | 1.149 ± 0.002 | 149 ± 1 | 0.46 ± 4 | |
2 | 93.44 | 7.63 ± 0.01 | 1.209 ± 0.002 | 4.032 ± 0.024 | 3.34 | 0.052 ± 0.001 | 0.032 ± 0.001 | 1.125 ± 0.001 | 125 ± 1 | 0.13 ± 5 | |
1&2 | 1.13 ± 0.28 | ||||||||||
3 | 59.84 | 2.81 ± 0.01 | 1.103 ± 0.008 | 3.59 ± 0.12 | 3.25 | 0.129 ± 0.001 | 0.078 ± 0.003 | 1.128 ± 0.002 | 128 ± 1 | 0.13 ± 12 | |
4 | 25.26 | 3.20 ± 0.01 | 0.119 ± 0.001 | 0.46 ± 0.01 | 3.85 | 0.012 ± 0.001 | 0.009 ± 0.001 | 1.140 ± 0.003 | 140 ± 3 | 0.14 ± 1 | |
3&4 | 0.14 ± 0.04 | ||||||||||
5 | 13.77 | 3.81 ± 0.03 | 0.172 ± 0.001 | 0.68 ± 0.02 | 3.98 | 0.015 ± 0.001 | 0.011 ± 0.001 | 1.151 ± 0.009 | 151 ± 8 | 0.20 ± 2 | |
6 | 39.56 | 29.9 ± 2.3 | 0.785 ± 0.004 | 2.51 ± 0.05 | 3.20 | 0.009 ± 0.001 | 0.005 ± 0.001 | 1.136 ± 0.003 | 136 ± 3 | n. d. | |
7 | 24.80 | 0.974 ± 0.002 | 0.199 ± 0.001 | 0.71 ± 0.02 | 3.55 | 0.067 ± 0.001 | 0.044 ± 0.001 | 1.145 ± 0.004 | 145 ± 4 | 0.42 ± 6 | |
5&6&7 | 0.07 ± 0.02 | ||||||||||
