Table 3 pIR-IRSL coarse grain and polymineral fine-grained dating of sediments at Tam Pà Ling: dose rate data, equivalent doses, and age estimates

From: Early presence of Homo sapiens in Southeast Asia by 86–68 kyr at Tam Pà Ling, Northern Laos

(A) Alpha and beta counting
Sample	Depth	Gamma	Beta	Cosmic-ray	Int/alpha	Water	Total	Accepted		Equivalent
code^a		dose rate	dose rate	dose rate	dose rate	content	dose rate	/run	Technique^g	dose	Age
	(m)	(Gy ka⁻¹)^b	(Gy ka⁻¹)^b	(Gy ka⁻¹)^c	(Gy ka⁻¹)^d	(%)^e	(Gy ka⁻¹)	aliquots^f		(Gy)^h,i	(ka)ⁱ
TPL12	5.72	1.670 ± 0.080	1.578 ± 0.066	0.013 ± 0.001	0.72 ± 0.10	30/30 ± 2	3.982 ± 0.186	13/24	pIR-IRSL₂₇₀	266 ± 14	67 ± 5
TPL13	6.00	1.453 ± 0.087	1.206 ± 0.054	0.013 ± 0.001	0.72 ± 0.10	30/30 ± 5	3.392 ± 0.209	5/32	pIR-IRSL₂₇₀	240 ± 50	71 ± 16
		1.453 ± 0.087	1.327 ± 0.052	0.013 ± 0.001	0.20 ± 0.04	30/30 ± 5	2.995 ± 0.179	9/13	PFG	194 ± 57	65 ± 19
TPL14	6.30	1.777 ± 0.083	1.623 ± 0.069	0.013 ± 0.001	0.72 ± 0.10	34/30 ± 5	4.133 ± 0.236	13/34	pIR-IRSL₂₇₀	307 ± 41	74 ± 11
		1.777 ± 0.083	1.786 ± 0.065	0.013 ± 0.001	0.24 ± 0.07	34/30 ± 5	3.812 ± 0.200	10/12	PFG	240 ± 44	63 ± 12
TPL15	6.67	1.591 ± 0.051	1.588 ± 0.073	0.013 ± 0.001	0.72 ± 0.10	40/30 ± 5	3.912 ± 0.212	4/8	pIR-IRSL₂₇₀	313 ± 36	80 ± 10
		1.591 ± 0.051	1.747 ± 0.032	0.013 ± 0.001	0.35 ± 0.09	40/30 ± 5	3.450 ± 0.190	6/11	PFG	295 ± 20	86 ± 8

(B) High-resolution gamma spectrometry
Sample	²³⁸U	²²⁶Ra	²¹⁰Pb	²²⁸Ra	²²⁸Th	⁴⁰K	Water	Total		Equivalent
code^j							content	dose rate^k	Technique^l	dose^m	Ageⁿ
	(Bq/kg)	(Bq/kg)	(Bq/kg)	(Bq/kg)	(Bq/kg)	(Bq/kg)	(%)	(Gy ka⁻¹)		(Gy)	(ka)
TPL14	69 ± 11	52.9 ± 4.7	67.5 ± 11.3	86.7 ± 8.4	96.2 ± 9.3	395 ± 54	34/30 ± 5	3.868 ± 0.316	pIR-IRSL₂₇₀	307 ± 41	79 ± 13
	69 ± 11	52.9 ± 4.7	67.5 ± 11.3	86.7 ± 8.4	96.2 ± 9.3	395 ± 54	34/30 ± 5	3.537 ± 0.309	PFG	240 ± 44	68 ± 14
TPL15	66 ± 10	57.4 ± 5.2	55.9 ± 9.5	93.3 ± 8.4	89.9 ± 9.9	512 ± 59	40/30 ± 5	3.891 ± 0.314	pIR-IRSL₂₇₀	313 ± 36	80 ± 11
	66 ± 10	57.4 ± 5.2	55.9 ± 9.5	93.3 ± 8.4	89.9 ± 9.9	512 ± 59	40/30 ± 5	3.667 ± 0.323	PFG	295 ± 20	80 ± 9

^aSamples processed using the 90–125 µm size fraction or polymineral fine grains (4–11 µm). Figure 3 contains the sampling locations.
^bBeta dose rates were estimated using a Geiger–Muller beta counting of dried and powdered sediment samples, gamma dose rates were estimated using thick source alpha counting measurements of dried and powdered sediment samples in the laboratory. The difference between these measurements was used to estimate potassium values.
^cTime-averaged cosmic-ray dose rates (for dry samples), each assigned an uncertainty of ± 10%.
^dAn internal dose rate of 0.72 ± 0.10 Gy/ka was estimated for all 90–125 µm feldspar grains. Mean ± total (1σ) uncertainty, calculated as the quadratic sum of the random and systematic uncertainties. For fine grains this column represents the alpha dose rate based on an effective alpha value for polymineral fine grains of 0.10 ± 0.01⁹². For all fine-grain dosimetry, no attenuation of beta was included⁴⁷.
^eField/time-averaged water contents, expressed as (mass of water/mass of dry sample) × 100. The latter values were used to correct the external gamma and beta dose rates.
^fTotal number of aliquots processed verses number of accepted aliquots- with an average acceptance rate of ~15–50%
^gpIR-IRSL270 indicates coarse grain feldspars using 90–125 µm grains, PFG represents a polymineral fine-grain measurement on small 4–11 µm grains.
^hEquivalent doses include a ± 2% systematic uncertainty associated with laboratory beta-source calibrations and represents a fading corrected D_e. Fading corrections according to ref. ⁸⁶
ⁱUncertainties at 68% confidence interval.
^jHigh-resolution gamma spectrometry to estimate the U, Th, and K concentrations in the dried and powdered sample, provide a comparison of dose rate, and to test the degree of disequilibrium occurring at the site. HRGS was only measured for samples TPL14 and TPL15. All other parameters such as cosmic dose rate, internal dose rate/alpha dose rate and number of aliquots remain the same as in Table A.
^kThe total dose rates for both samples is slightly lower than Table A resulting in a higher age estimate.
^lpIR-IRSL₂₇₀ indicates coarse grain feldspars using 90–125 µm grains, PFG represents a polymineral fine-grain measurement on small 4–11 µm grains.
^mThe Equivalent dose represents a fading corrected D_e. Fading corrections according to ref. ⁸⁶
ⁿThe age estimates have been calculated using these alternate dose rate estimations.

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Table 3 pIR-IRSL coarse grain and polymineral fine-grained dating of sediments at Tam Pà Ling: dose rate data, equivalent doses, and age estimates

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