Title: Table F
Author: RSES
Last saved by: Charlotte Skelton
Company: ANU

Supplementary Table 15. Results of laser fusion ^40Ar/^39Ar dating of single crystals of anorthoclase from four pumice clasts from 
the Lokalalei Tuff (=D), Lokalalei Member, Nachukui Formation, in Lomekwi Laga near hominin site, west of Lake Turkana, northern Kenya. Sample 83-284 is a pumice clast from a cliff in Il Ingumwai, Area 207, Koobi Fora

Sample

^36Ar/^39Ar
x 10^-4

^37Ar/^39Ar
x 10^-3

^40Ar/^39Ar

K/Ca

^40Ar*/^39Ar_K
± c.v.

% ^40Ar*

^39Ar
10^-14mol

Calculated age
Ma ± 1 s.d.

93-1064A anorthoclase; J = 4.391E-4 ± 0.25%; level 11, G432
1 | 19.047 ±  3.23% | 24.057 ±  1.34% | 3.763 ± 0.15% | 22 | 3.183 ± 0.61% | 84.6 | 0.70 | 2.519 ± 0.017
2 | 104.970 ±  0.67% | 25.901 ±  1.10% | 6.292 ± 0.56% | 20 | 3.173 ± 1.29% | 50.4 | 1.10 | 2.511 ± 0.033
3 | 5.969 ±  6.80% | 37.763 ±  1.17% | 3.371 ± 0.14% | 14 | 3.179 ± 0.40% | 94.3 | 0.89 | 2.516 ± 0.012
4 | 4.173 ±  9.90% | 22.110 ±  2.30% | 3.332 ± 0.28% | 24 | 3.191 ± 0.48% | 95.8 | 0.77 | 2.526 ± 0.014
5 | 6.213 ±  7.76% | 20.817 ±  0.87% | 3.432 ± 0.63% | 25 | 3.231 ± 0.81% | 94.1 | 1.03 | 2.557 ± 0.022
6 | 7.084 ±  4.18% | 40.323 ±  0.54% | 3.390 ± 0.27% | 13 | 3.165 ± 0.40% | 93.4 | 0.78 | 2.505 ± 0.012
7 | 6.985 ±  6.46% | 24.469 ±  1.42% | 3.391 ± 0.21% | 22 | 3.167 ± 0.48% | 93.4 | 0.98 | 2.507 ± 0.014
| Arithmetic mean K/Ca (n = 7) | 20 ± 5 | Arithmetic mean age (n= 7) Weighted mean age (n= 7) | 2.520 ± 0.018 2.516 ± 0.008
93-1064B anorthoclase; J = 4.546E-4 ± 0.50%; level 7, K428
1 | 3.024 ± 20.65% | 2.454 ± 28.36% | 3.187 ± 0.18% | 214 | 3.078 ± 0.63% | 96.6 | 0.48 | 2.523 ± 0.020
2 | 4.562 ±  5.68% | 1.929 ± 17.80% | 3.290 ± 0.31% | 273 | 3.135 ± 0.41% | 95.3 | 1.45 | 2.570 ± 0.017
3 | 5.656 ±  4.48% | 3.044 ± 10.72% | 3.278 ± 0.21% | 173 | 3.092 ± 0.33% | 94.3 | 0.83 | 2.534 ± 0.015
4 | 6.495 ±  5.87% | 1.965 ± 13.63% | 3.283 ± 0.28% | 268 | 3.071 ± 0.47% | 93.6 | 1.37 | 2.517 ± 0.017
5 | 3.458 ±  3.02% | 1.419 ±  7.76% | 3.192 ± 0.19% | 371 | 3.070 ± 0.22% | 96.2 | 1.61 | 2.516 ± 0.014
6 | 3.903 ±  9.33% | 1.268 ± 38.47% | 3.217 ± 1.07% | 415 | 3.082 ± 1.17% | 95.8 | 0.82 | 2.526 ± 0.032
| Arithmetic mean K/Ca (n =  6) | 286 ± 92 | Arithmetic mean age (n= 6) Weighted mean age (n = 6) | 2.531 ± 0.020 2.528 ± 0.013
93-1064C anorthoclase; J = 4.538E ± 0.40%; level 8, K428
1 | 7.555 ±  7.53% | 2.015 ± 45.00% | 3.264 ± 0.21% | 261 | 3.021 ± 0.60% | 92.6 | 0.51 | 2.471 ± 0.018
2 | 10.151 ±  3.12% | 2.026 ± 16.64% | 3.445 ± 0.17% | 260 | 3.126 ± 0.35% | 90.7 | 1.21 | 2.557 ± 0.014
3 | 7.505 ±  6.49% | 1.754 ±  8.54% | 3.337 ± 0.19% | 300 | 3.095 ± 0.51% | 92.8 | 1.29 | 2.532 ± 0.016
4 | 6.350 ±  7.93% | 4.157 ±  7.44% | 3.295 ± 0.20% | 127 | 3.088 ± 0.53% | 93.7 | 1.04 | 2.527 ± 0.017
5 | 3.648 ±  9.61% | 2.704 ±  5.74% | 3.217 ± 0.20% | 195 | 3.089 ± 0.39% | 96.0 | 1.14 | 2.528 ± 0.014
6 | 3.129 ± 10.49% | 2.010 ± 18.29% | 3.205 ± 0.17% | 262 | 3.092 ± 0.36% | 96.5 | 1.16 | 2.530 ± 0.014
7 | 9.329 ±  5.23% | 2.189 ± 12.41% | 3.455 ± 0.20% | 240 | 3.160 ± 0.50% | 91.4 | 0.75 | 2.585 ± 0.017
8 | 11.965 ±  5.74% | 2.995 ± 17.51% | 3.449 ± 0.20% | 176 | 3.076 ± 0.70% | 89.2 | 0.59 | 2.517 ± 0.020
| Arithmetic mean K/Ca (n= 8) | 228 ± 57 | Arithmetic mean age (n = 8) Weighted mean age (n = 8) | 2.531 ± 0.033 2.535 ± 0.011
93-1065 anorthoclase; J = 4.384E-4 ± 0.25%; level 10, G432
1 | 12.450 ±  4.00% | 2.560 ± 10.50% | 3.554 ± 0.45% | 206 | 3.166 ± 0.69% | 89.1 | 0.39 | 2.502 ± 0.018
2 | 4.273 ±  5.89% | 5.514 ±  3.69% | 3.326 ± 0.19% | 95 | 3.181 ± 0.31% | 95.6 | 0.85 | 2.513 ± 0.010
3 | 8.682 ± 19.04% | 5.682 ±  5.68% | 3.406 ± 0.59% | 93 | 3.130 ± 1.69% | 91.9 | 0.34 | 2.474 ± 0.042
4 | 5.146 ± 13.43% | 3.402 ±  2.55% | 3.340 ± 0.38% | 155 | 3.169 ± 0.76% | 94.9 | 0.58 | 2.504 ± 0.020
5 | 39.595 ±  1.75% | 1.631 ± 10.26% | 4.395 ± 0.16% | 323 | 3.205 ± 0.68% | 72.9 | 0.87 | 2.533 ± 0.018
6 | 8.051 ±  3.75% | 11.265 ±  0.73% | 3.438 ± 0.22% | 47 | 3.182 ± 0.37% | 92.5 | 1.49 | 2.514 ± 0.011
7 | 11.352 ±  3.80% | 6.055 ±  5.56% | 3.493 ± 0.25% | 87 | 3.138 ± 1.08% | 89.8 | 0.49 | 2.480 ± 0.028
Arithmetic mean K/Ca (n = 7) | 144 ± 95 | Arithmetic mean age (n = 7) | 2.503 ± 0.020
| | | | | Weighted mean age (n = 7) | 2.512 ± 0.008
83-284 anorthoclase; J = 5.289E-4 ± 0.30%; level 6, ANU47
1 | 0.774 ± 23.37% | 38.921 ±  0.91% | 2.707 ± 0.14% | 14 | 2.662 ± 0.25% | 98.3 | 1.45 | 2.538 ± 0.010
[2 | 85.722 ±  0.69% | 50.209 ±  1.27% | 5.345 ± 0.12% | 10 | 2.791 ± 0.67% | 52.2 | 1.79 | 2.661 ± 0.019]
3 | 2.306 ±  8.57% | 31.021 ±  0.90% | 2.746 ± 0.16% | 17 | 2.655 ± 0.28% | 96.7 | 0.85 | 2.531 ± 0.010
5 | 17.309 ±  2.32% | 35.041 ±  0.57% | 3.216 ± 0.18% | 15 | 2.681 ± 0.49% | 83.4 | 0.77 | 2.557 ± 0.015
6 | 2.133 ±  3.34% | 33.802 ±  0.89% | 2.759 ± 0.15% | 16 | 2.673 ± 0.17% | 96.9 | 2.22 | 2.549 ± 0.009
7 | 3.036 ±  5.53% | 50.984 ±  0.55% | 2.777 ± 0.15% | 10 | 2.666 ± 0.24% | 96.0 | 2.19 | 2.542 ± 0.010
8 | 14.156 ±  1.68% | 10.657 ±  3.59% | 3.126 ± 0.20% | 49 | 2.683 ± 0.35% | 85.8 | 1.17 | 2.558 ± 0.012
10 | 25.235 ±  0.94% | 38.167 ±  0.86% | 3.438 ± 0.14% | 14 | 2.670 ± 0.32% | 77.7 | 2.72 | 2.546 ± 0.011
| Arithmetic mean K/Ca (n =  7) | 19 ± 13 | Arithmetic mean age (n = 7) Weighted mean age (n = 7) | 2.546 ± 0.010 2.544 ± 0.008

λ = 5.543 x 10^-10 a^-1        Sensitivity 2.5 (±~15%) x 10^-17 mol/mV 	Bracketed results excluded from mean age calculation
(^36Ar/^37Ar)_Ca = 3.50 x 10^-4	(^39Ar/^37Ar)_Ca = 7.86 x 10^-4	(^40Ar/^39Ar)_K = 0.020 to 0.027 
^40Ar* – radiogenic ^40Ar	^39Ar_K – K derived ^39Ar	Irradiated 24 hours in X33 or X34, HIFAR reactor
Mass of alkali feldspar used in each analysis in range: 93-1064A – 1.3 to 2.5 mg; 93-1064B – 1.0 to 3.0 mg; 
	93-1064C – 1.1 to 2.4 mg; 93-1065 – 0.7 to 2.5 mg; 83-284 – 1.2 to 3.7 mg
Fluence monitor: 92-176 sanidine from Fish Canyon Tuff; K-Ar reference age utilized: 28.1 Ma
All errors are one standard deviation. Uncertainty on the ^40Ar*/^39Ar_K ratio is the analytical error. This error is combined quadratically with the estimated error of J to yield the quoted error for each age