Testing feldspar luminescence dating of young archaeological heated materials using potshards from Pella (Tell Tabqat Fahl) in the Jordan valley

Relevant radiocarbon ages for samples from the destruction horizon. The calibration of ¹⁴C dates with the calibration software OxCal version 3.10., and the calibration curve lntCal09 (Fischer, 2013)1.

	VERA# (ABA)*	¹⁴C age (BP)	Era and phase	Calibrated 2σ BCE
Pella	VERA 5311	2940 ± 35	IAI-II	1270–1020 BCE (94%)
Pella	VERA 5301	2930 ± 35	IAI-II	1260–1010 BCE (91%)
Pella	VERA 5316	2925 ± 35	IAI-II	1260–1010 BCE (95%)
Pella	VERA 5310	2885 ± 35	IAI-II	1210–970 BCE (93%)

1 Vera 5308 and 5316 were processed by Professor Peter Fischer at Vienna in 2011, as part of an SCIEM2000 project on the Iron Age chronology of the Jordan Valley (Wild and Fischer, 2013, 461, n.90). Bourke would like to thank Fischer for making these dates available for discussion here.

* samples were chemically pre-treated with the (acid-base-acid) method

Potshards were collected from layer 10.6 and the stratigphicaly underlying layers 15.1 and 15.2 (bottom layer) (photograph by S. Bourke).

Table 2

Activities derived from gamma spectrometry for the standards used in Ankjærgaard and Murray (2007) together with a comparison of their conversion factors and those derived here using the modifactions discussed in the text.

	²³⁸U (Bq·kg^-1)	²³²Th (Bq·kg^-1)	⁴⁰K (Bq·kg^-1)	Observed beta counts (cks^-1)	CR/β (ks^-1/(Gy·ka^-1))	MCR/β (ks^-1/(Gy·ka^-1))	CR/α (ks^-1/(Gy·ka^-1))
²³⁸U standard	972 ± 9	14.7 ± 0.7	515 ± 10	739.4 ± 1.6	66.7 ± 3.1	53.05 ± 0.96	3.9 ± 0.1
²³²Th standard	9.36 ± 1.23	1792 ± 30	571 ± 14	878.56 ± 1.84	61.3 ± 0.8	56.7 ± 1.9	2.4 ± 0.1
⁴⁰K standard	-	-	13767 ± 94		61.20 ± 1	61.20 ± 1	-

CR/β — Count rate/beta dose rate, (Ankjærgaard and Murray, 2007)

MCR/β — Modified Count rate/beta dose rate

CR/α — Count rate/alpha dose rate

Table 3

gamma spectrometry analyses of mixtures of 14 potshards from each layer, and the fractional contribution from each nuclide to beta count rate factors.

	Beta dose rate (Gy/ka)			Alpha dose rate (Gy/ka)

	²³⁸U	²³²Th	⁴⁰K	²³⁸U	²³²Th
L10.6	1.21 ± 0.02	0.137 ± 0.006	1.13 ± 0.05	22.9 ± 0.3	3.6 ± 0.2
L15.1	2.32 ± 0.04	0.182 ± 0.008	1.51 ± 0.12	44.1 ± 0.6	4.9 ± 0.3
L15.2	0.843 ± 0.014	0.09 ± 0.01	0.79 ± 0.05	16.1 ±0.2	2.5 ± 0.2
Fractional beta count rate contribution from each nuclide

	²³⁸U	²³²Th	⁴⁰K	Observed average beta count rate (cks^-1)
L10.6	0.45 ± 0.02	0.055 ± 0.003	0.49 ± 0.03	150 ± 2
L15.1	0.55 ± 0.03	0.045 ± 0.005	0.41 ±0.05	180 ± 3
L15.2	0.45 ± 0.02	0.054 ± 0.005	0.5 ± 0.04	198 ± 2

Table 4

Derived beta and alpha dose rates using the observed beta count rate from each shard. The gamma dose derived from gamma spectrometry analyses of sediment samples from each layer is given at the end of the table.

Sample	Observed beta counts (cks^-1)	Beta dose rate (Gy/ka)	Alpha dose rate (Gy/ka)
L10.6.1	170 ± 2	2.98 ± 0.10	28.83 ± 0.04
L10.6.2	131 ± 2	2.30 ± 0.08	22.32 ± 0.03
L10.6.3	170 ± 2	2.98 ± 0.10	28.90 ± 0.04
L10.6.4	441 ± 3	7.7 ± 0.3	74.87 ± 0.09
L10.6.5	168 ± 2	2.94 ± 0.10	28.45 ± 0.04
L10.6.6	156 ± 2	2.73 ± 0.09	26.43 ± 0.04
L10.6.7	153 ± 2	2.68 ± 0.09	25.98 ± 0.03
L10.6.8	139 ± 2	2.44 ± 0.08	23.60 ± 0.03
L10.6.9	142 ± 2	2.49 ± 0.08	24.12 ± 0.03
L10.6.11	105 ± 2	1.85 ± 0.07	17.86 ± 0.02
L10.6.12	183 ± 2	3.22 ± 0.11	31.15 ± 0.04
L10.6.13	177 ± 2	3.11 ± 0.10	30.06 ± 0.04
L10.6.14	123 ± 2	2.16 ± 0.07	20.90 ± 0.03
L10.6.15	136 ± 2	2.39 ± 0.08	23.13 ± 0.03
L10.6.16	168 ± 2	2.95 ± 0.10	28.51 ± 0.04
L10.6.17	217 ± 3	3.81 ± 0.13	36.83 ± 0.05
L10.6.18	156 ± 2	2.74 ± 0.10	26.55 ± 0.04
L10.6.19	106 ± 2	1.85 ± 0.07	17.94 ± 0.03
L10.6.20	131.6 ± 2	2.31 ± 0.08	22.34 ± 0.03
L15.1.1	192 ± 3	3.4 ± 0.2	37.64 ± 0.08
L15.1.2	165 ± 3	2.9 ± 0.2	32.32 ± 0.07
L15.1.3	188 ± 3	3.3 ± 0.2	36.89 ± 0.07
L15.1.4	172 ± 3	3.1 ± 0.2	33.76 ± 0.07
L15.1.6	177 ± 2	3.2 ± 0.2	34.8 ± 0.8
L15.1.7	144 ± 2	2.55 ± 0.14	28.17 ± 0.06
L15.1.8	196 ± 2	3.5 ± 0.2	38.55 ± 0.08
L15.1.9	172 ± 2	3.1 ± 0.2	33.68 ± 0.07
L15.1.10	292 ± 3	5.2 ± 0.3	57.38 ± 0.11
L15.1.11	219 ± 3	3.9 ± 0.2	43.03 ± 0.08
L15.1.12	123 ± 2	2.19 ± 0.12	24.18 ± 0.08
L15.1.13	144 ± 2	2.56 ± 0.14	28.30 ± 0.06
L15.1.14	165 ± 2	2.9 ± 0.2	32.47 ± 0.06
L15.1.15	177 ± 2	3.2 ± 0.2	34.81 ± 0.07
L15.1.16	222 ± 2	3.9 ± 0.2	43.51 ± 0.08
L15.1.17	172 ± 2	3.1 ± 0.2	33.72 ± 0.07
L15.1.18	135 ± 2	2.41 ± 0.13	26.58 ± 0.05
L15.1.19	248 ± 3	4.4 ± 0.2	48.77 ± 0.09
L15.1.20	169 ± 3	3.0 ± 0.2	33.18 ± 0.07
L15.2.1	157 ± 2	2.76 ± 0.11	26.79 ± 0.04
L15.2.2	134 ± 2	2.34 ± 0.10	22.74 ± 0.04
L15.2.3	281 ± 3	4.9 ± 0.2	47.80 ± 0.07
L15.2.4	108 ± 2	1.89 ± 0.08	18.36 ± 0.03
L15.2.5	179 ± 3	3.13 ± 0.13	30.39 ± 0.05
L15.2.6	264 ± 3	4.6 ± 0.2	44.97 ± 0.07
L15.2.7	283 ± 3	5.0 ± 0.2	48.17 ± 0.05
L15.2.8	176 ± 2	3.08 ± 0.12	29.89 ± 0.05
L15.2.9	133 ± 2	2.34 ± 0.10	22.66 ± 0.04
L15.2.10	259 ± 3	4.6 ± 0.2	44.15 ± 0.07
L15.2.12	221 ± 2	3.9 ± 0.2	37.68 ± 0.06
L15.2.13	211 ± 2	3.7 ± 0.2	35.98 ± 0.06
L15.2.14	200 ± 2	3.50 ± 0.14	34.00 ± 0.05
L15.2.15	184 ± 2	3.23 ± 0.13	31.35 ± 0.05
L15.2.17	172 ± 2	3.01 ± 0.12	29.25 ± 0.05
L15.2.18	168 ± 2	2.94 ± 0.12	28.54 ± 0.05
L15.2.19	162 ± 2	2.84 ± 0.11	27.55 ± 0.04
L15.2.20	136 ± 2	2.39 ± 0.10	23.21 ± 0.04
External dose rate

Soil samples	Gamma dose rate (Gy/ka)	²³⁸U (Bq/kg)	²³²Th (Bq/kg)	⁴⁰K (Bq/kg)
L10.6	1.01 ± 0.12	132 ± 32	13.8 ± 1.6	502 ± 25
L15.1	1.64 ± 0.15	180 ± 24	12.9 ± 1.3	341 ± 21
L15.2	1.26 ± 0.11	130 ± 23	11.4 ± 1.8	325 ± 24

Table 5

Summary of ages and related data for 52 potshards. The samples rejected because of low luminescence intensity (test dose response minus background, T-Bg, < 1000) are identified by italics, and the single underlined sample was rejected because of poor recycling ratio. The 3 outliers discussed in the text are highlighted in grey.

Sample No.		Age (ka)	Rand. Error (ka)	De (Gy)	Dose rate (Gy/ka)	(T-Bg)
1	L10.6.1	2.4 ± 0.2	0.2	12.7 ± 0.6	5.2 ± 0.4	2802
2	L10.6.2	2.4 ± 0.2	0.2	10.5 ± 0.6	4.3 ± 0.3	2058
3	L10.6.3	2.9 ± 0.3	0.2	15.2 ± 1.1	5.2 ± 0.4	1334
4	L10.6.4	2.8 ± 0.3	0.2	37.4 ± 2.4	13.5 ± 0.9	1852
5	L10.6.5	2.7 ± 0.3	0.2	13.9 ± 0.9	5.2 ± 0.4	3256
6	L10.6.6	2.4 ± 0.2	0.11	12.0 ± 0.2	5.0 ± 0.4	11175
7	L10.6.7	2.4 ± 0.2	0.11	12.04 ± 0.2	5.1 ± 0.4	11127
8	L10.6.8	3.0 ± 0.2	0.13	14.2 ± 0.2	4.6 ± 0.3	2870
9	L10.6.9	5.0 ± 0.7	0.6	22.2 ± 2.7	4.5 ± 0.4	547
10	L10.6.11	10.7 ± 3.5	3.4	38.7 ± 12.3	3.6 ± 0.3	549
11	L10.6.12	3.8 ± 0.5	0.4	22.1 ± 1.9	5.8 ± 0.4	2995
12	L10.6.13	3.2 ± 0.6	0.6	17.5 ± 3.1	5.5 ± 0.5	670
13	L10.6.15	6.6 ± 2.3	2.3	29.1 ± 9.9	4.4 ± 0.3	448
14	L10.6.16	2.6 ± 0.2	0.11	13.7 ± 0.3	5.2 ± 0.4	3210
15	L10.6.17	3.1 ± 0.3	0.2	19.3 ± 0.7	6.3 ± 0.5	4630
16	L15.1.1	3.7 ± 0.6	0.5	25.2 ± 2.8	6.8 ± 0.6	1275
17	L15.1.2	2.9 ± 0.3	0.2	16.89 ± 1.0	5.8 ± 0.5	1126
18	L15.1.3	2.4 ± 0.3	0.2	15.5 ± 0.8	6.6 ± 0.6	2601
19	L15.1.4	2.3 ± 0.2	0.14	14.2 ± 0.3	6.2 ± 0.6	8952
20	L15.1.6	2.5 ± 0.2	0.15	15.6 ± 0.3	6.3 ± 0.6	5894
21	L15.1.7	3.4 ± 0.6	0.5	18.3 ± 2.6	5.5 ± 0.5	659
22	L15.1.8	3.0 ± 0.4	0.3	20.8 ± 1.8	6.9 ± 0.6	3714
23	L15.1.9	3.5 ± 0.4	0.3	22.1 ± 1.3	6.3 ± 0.5	1257
24	L15.1.10	3.7 ± 0.4	0.2	32.7 ± 0.7	8.9 ± 0.9	3879
25	L15.1.11	4.1 ± 0.5	0.3	29.3 ± 1.5	7.2 ± 0.7	3146
26	L15.1.12	8.7 ± 1.3	1.1	38.8 ± 4.4	4.5 ± 0.4	3631
27	L15.1.13	3.2 ± 0.4	0.3	16.1 ± 1.2	5.0 ± 0.5	4649
28	L15.1.14	5.9 ± 3.0	2.9	35.7 ± 17.6	6.1 ± 0.5	381
29	L15.1.15	1.7 ± 0.8	0.8	10.3 ± 4.9	6.1 ± 0.6	353
30	L15.1.16	2.5 ± 0.3	0.3	18.6 ± 1.8	7.4 ± 0.7	1164
31	L15.1.17	4.1 ± 0.5	0.4	25.2 ± 1.7	6.2 ± 0.6	782
32	L15.1.18	2.7 ± 0.9	0.9	13.9 ± 4.3	5.1 ± 0.5	616
33	L15.1.19	1.5 ± 0.2	0.2	11.9 ± 1.2	8.0 ± 0.8	1221
34	L15.1.20	4.0 ± 0.4	0.3	24.3 ± 0.9	6.1 ± 0.5	3073
35	L15.2.1	2.6 ± 0.3	0.2	13.3 ± 0.9	5.2 ± 0.4	1498
36	L15.2.2	2.7 ± 0.2	0.12	12.3 ± 0.3	4.6 ± 0.3	3561
37	L15.2.3	2.3 ± 0.2	0.14	18.9 ± 0.9	8.4 ± 0.7	1617
38	L15.2.4	6.5 ± 0.6	0.4	25.3 ± 1.4	3.9 ± 0.3	1284
39	L15.2.5	2.9 ± 0.3	0.2	16.1 ± 0.8	5.6 ± 0.4	1322
40	L15.2.6	1.69 ± 0.14	0.12	13.6 ± 0.5	8.1 ± 0.6	5259
41	L15.2.7	6.7 ± 0.7	0.6	58.2 ± 4.7	8.7 ± 0.6	3657
42	L15.2.8	2.5 ± 0.4	0.4	14 ± 2	5.6 ± 0.4	1245
43	L15.2.9	2.8 ± 0.6	0.6	12.8 ± 2.8	4.6 ± 0.3	756
44	L15.2.10	2.5 ± 0.2	0.10	19.5 ± 0.3	7.7 ± 0.6	10969
45	L15.2.12	4.2 ± 1.0	1.0	28.5 ± 6.6	6.8 ± 0.5	903
46	L15.2.13	1.8 ± 0.2	0.13	12.1 ± 0.8	6.8 ± 0.5	2987
47	L15.2.14	4.8 ± 0.6	0.5	31.5 ± 2.9	6.5 ± 0.5	523
48	L15.2.15	4.4 ± 0.3	0.2	26.2 ± 0.6	6.0 ± 0.4	12303
49	L15.2.17	4.5 ± 0.5	0.4	23.9 ± 1.8	5.3 ± 0.4	1065
50	L15.2.18	1.95 ± 0.2	0.2	10.9 ± 0.8	5.6 ± 0.4	4011
51	L15.2.19	2.0 ± 0.2	0.12	10.9 ± 0.3	5.4 ± 0.4	2620
52	L15.2.20	3.0 ± 0.6	0.6	14.0 ± 2.6	4.7 ± 0.3	956

Representative dose response curve and (inset) natural and regenerated stimulation curves (a) for post-IR IRSL signals at 290°C and(b) for IR signal at 50°C for shard L15.1.4, from layer L15.1.

Dependence of D_e values on the first IR stimulation temperature for three representative samples (a) L10.6.12, (b) L15.14 and (c) L15.2.10. Red symbols — IR and blue symbols — pIRIR₂₉₀.

Dependence of D_e values on the preheat temperature for three representative samples (a) L10.6.12, (b) L15.1.8 and (c) L15.2.13. Red symbols — IR₅₀, blue symbols — pIRIR.

Ratios of measured equivalent dose to the given dose for both signals in dose recovery measurements: (a) samples heated to 500°C in oven before giving laboratory dose (a. 1 for pIRIR₂₉₀ signal and a.2 for IR₅₀signal); (b) samples exposed in solar stimulator for 4 hours before giving laboratory. Note that the IR₅₀ signals were too weak to derive a meaningful dose recovery histogram; (c) samples given laboratory dose in addition to their natural dose, the measured dose to the given dose ratio was calculated after subtracting the natural dose from the total measured dose (c. 1 and c.2 for pIRIR₂₉₀ and IR₅₀ respectively).

Comparison of IR₅₀ D_e and pIRIR₂₉₀ D_e; open circles represent age outliers (see text).

Table 6

Summary of average ages of each layer and the site average age.

Layer	Number of accepted samples	Age average (ka)	Random uncertainty (ka)	Total uncertainty (ka)	Over-dispersion (ka)	Over-dispersion %
With outliers

L10.6	11	2.79	0.13	0.24	0.29	10.5
L15.1	14	3.45	0.45	0.54	1.14	36.1
L15.2	13	3.32	0.49	0.51	1.27	42.2

Without outliers

L10.6	11	2.79	0.13	0.24	0.29	10.5
L15.1	13	3.02	0.21	0.30	0.74	25.1
L15.2	11	2.72	0.28	0.34	0.75	28.6

Site Average Age

Including outliers	38	3.20	0.20	0.30	1.0	33.8
Excluding outliers	35	2.85	0.12	0.22	0.66	24.1

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DOI: https://doi.org/10.1515/geochr-2015-0056 | Journal eISSN: 1897-1695 | Journal ISSN: 1733-8387

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Language: English

Page range: 98 - 110

Submitted on: Mar 19, 2016

Accepted on: Jan 30, 2017

Published on: May 2, 2017

Published by: Sciendo

In partnership with: Paradigm Publishing Services

Keywords:

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© 2017 Sahar Al Khasawneh, Andrew S. Murray, Stephen Bourke, Dominik Bonatz, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 44 (2017): Issue 1 (January 2017)

Testing feldspar luminescence dating of young archaeological heated materials using potshards from Pella (Tell Tabqat Fahl) in the Jordan valley

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