Skip to main content
. 2021 Apr 12;118(16):e2020042118. doi: 10.1073/pnas.2020042118

Table 1.

U-series concentrations, activity ratios, and calculated ages for YFT1 OES samples

Uncorrected age Corrected age§ 230Th/U burial age
Sample ID Tablet U (ppb) 232Th (ppb) (230Th /232Th)* Initial (234U /238U) ± (2σ, ab.) ka ± (2σ), ka ka ± (2σ), ka Ka ± (2σ), ka Included in age model?
YFT1-1A Outer 160.13 0.11 3,162.48 1.0853 0.0039 115.43 1.96 115.41 1.96 116.1 3.4 Y
Inner 113.32 0.11 2,262.61 1.0892 0.0038 114.34 1.90 114.31 1.90
YFT1-1C Outer 160.06 0.10 3,333.70 1.0755 0.0035 113.26 1.04 113.24 1.04 114.5 2.2 Y
Inner 115.33 0.11 2,285.56 1.0754 0.0033 111.11 2.55 111.08 2.55
YFT1-1D Outer 154.51 0.00 1,375.46 1.0982 0.0031 110.46 1.66 110.42 1.66 N/A N
Inner 115.31 0.00 1,173.90 1.1230 0.0036 115.82 1.43 115.77 1.44
YFT1-1E Outer 69.41 0.00 1,771.95 1.0884 0.0044 107.57 1.29 107.55 1.29 N/A N
Inner 58.78 0.00 2,307.78 1.0827 0.0037 110.86 1.19 110.84 1.19
  YFT1-3C Outer 91.11 0.06 3,091.88 1.0849 0.0038 113.57 1.11 113.56 1.11 114.3 0.9 Y
Inner 58.37 0.07 1,843.26 1.0899 0.0056 115.05 1.36 115.02 1.36
  YFT1-6D Outer 46.38 0.26 419.50 1.1860 0.0046 118.25 0.98 118.12 0.98 118.2 0.8 Y
Inner 34.67 0.26 318.11 1.1961 0.0070 118.45 1.56 118.28 1.57
  YFT1-6E Outer 46.92 0.34 324.26 1.1753 0.0093 117.81 1.99 117.65 1.99 118.2 3.2 Y
Inner 31.72 0.38 194.33 1.1945 0.0090 116.92 1.84 116.65 1.84
  YFT1-10A Outer 29.98 1.37 52.14 1.2342 0.0240 115.02 3.86 113.95 3.88 114.6 6.4 Y
Inner 24.80 0.79 74.46 1.2411 0.0108 113.60 2.45 112.87 2.48
  YFT1-10E Outer 32.50 0.56 149.89 1.3697 0.0061 113.89 1.46 113.53 1.47 115.1 3.0 Y
Inner 27.37 0.36 187.21 1.3190 0.0064 111.97 1.67 111.69 1.68
  YFT1-12F Outer 17.39 0.69 58.93 1.2252 0.0054 110.93 2.12 109.99 2.18 110.2 3.3 N
Inner 12.59 0.76 38.46 1.2301 0.0068 111.10 1.73 109.65 1.91
  YFT1-12G Outer 23.32 0.78 67.73 1.1545 0.0051 116.33 1.75 115.48 1.81 116.9 3.1 Y
Inner 20.23 0.63 71.82 1.1512 0.0057 113.93 1.74 113.14 1.80
  YFT1-12I Outer 22.52 0.60 83.82 1.1553 0.0032 114.08 1.75 113.40 1.79 114.5 2.8 Y
Inner 15.66 0.51 68.31 1.1595 0.0061 112.10 1.94 111.28 2.00
  YFT1-12J Outer 23.38 0.97 57.49 1.2356 0.0038 115.75 1.82 114.76 1.91 116.7 3.2 Y
Inner 21.90 0.37 138.97 1.2242 0.0085 111.68 2.36 111.29 2.37

YFT1 OES naming convention: YFT1-[layer group][individual]. Reference SI Appendix for details of analytical methods and Dataset S1B for comprehensive data table.

*

All isotope ratios are activity ratios.

Initial (234U/238U) is back calculated from the measured ratio and the corrected age.230Th/U burial ages in italics are calculated from the weighted mean of two subsamples.

Uncorrected ages are calculated from measured ratios. Decay constants used for all ages are those of ref. 46 for 238U and ref. 47 for 230Th and 234U.

§

Detritus-corrected ages were corrected for U and 232Th from detritus using (232Th/238U) = 1.21 ± 0.60, (230Th/238U) = 1.0 ± 0.1, and (234U/238U) = 1.0 ± 0.1.