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


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Figure 1

Contour map of Pella with location map shown inset.
Contour map of Pella with location map shown inset.

Figure 2

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

Figure 3

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.
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.

Figure 4

Dependence of De 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 De 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.

Figure 5

Dependence of De 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.
Dependence of De 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.

Figure 6

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 IR50 signal); (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).
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 IR50 signal); (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).

Figure 7

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

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)
1L10.6.12.4 ± 0.20.212.7 ± 0.65.2 ± 0.42802
2L10.6.22.4 ± 0.20.210.5 ± 0.64.3 ± 0.32058
3L10.6.32.9 ± 0.30.215.2 ± 1.15.2 ± 0.41334
4L10.6.42.8 ± 0.30.237.4 ± 2.413.5 ± 0.91852
5L10.6.52.7 ± 0.30.213.9 ± 0.95.2 ± 0.43256
6L10.6.62.4 ± 0.20.1112.0 ± 0.25.0 ± 0.411175
7L10.6.72.4 ± 0.20.1112.04 ± 0.25.1 ± 0.411127
8L10.6.83.0 ± 0.20.1314.2 ± 0.24.6 ± 0.32870
9L10.6.95.0 ± 0.70.622.2 ± 2.74.5 ± 0.4547
10L10.6.1110.7 ± 3.53.438.7 ± 12.33.6 ± 0.3549
11L10.6.123.8 ± 0.50.422.1 ± 1.95.8 ± 0.42995
12L10.6.133.2 ± 0.60.617.5 ± 3.15.5 ± 0.5670
13L10.6.156.6 ± 2.32.329.1 ± 9.94.4 ± 0.3448
14L10.6.162.6 ± 0.20.1113.7 ± 0.35.2 ± 0.43210
15L10.6.173.1 ± 0.30.219.3 ± 0.76.3 ± 0.54630
16L15.1.13.7 ± 0.60.525.2 ± 2.86.8 ± 0.61275
17L15.1.22.9 ± 0.30.216.89 ± 1.05.8 ± 0.51126
18L15.1.32.4 ± 0.30.215.5 ± 0.86.6 ± 0.62601
19L15.1.42.3 ± 0.20.1414.2 ± 0.36.2 ± 0.68952
20L15.1.62.5 ± 0.20.1515.6 ± 0.36.3 ± 0.65894
21L15.1.73.4 ± 0.60.518.3 ± 2.65.5 ± 0.5659
22L15.1.83.0 ± 0.40.320.8 ± 1.86.9 ± 0.63714
23L15.1.93.5 ± 0.40.322.1 ± 1.36.3 ± 0.51257
24L15.1.103.7 ± 0.40.232.7 ± 0.78.9 ± 0.93879
25L15.1.114.1 ± 0.50.329.3 ± 1.57.2 ± 0.73146
26L15.1.128.7 ± 1.31.138.8 ± 4.44.5 ± 0.43631
27L15.1.133.2 ± 0.40.316.1 ± 1.25.0 ± 0.54649
28L15.1.145.9 ± 3.02.935.7 ± 17.66.1 ± 0.5381
29L15.1.151.7 ± 0.80.810.3 ± 4.96.1 ± 0.6353
30L15.1.162.5 ± 0.30.318.6 ± 1.87.4 ± 0.71164
31L15.1.174.1 ± 0.50.425.2 ± 1.76.2 ± 0.6782
32L15.1.182.7 ± 0.90.913.9 ± 4.35.1 ± 0.5616
33L15.1.191.5 ± 0.20.211.9 ± 1.28.0 ± 0.81221
34L15.1.204.0 ± 0.40.324.3 ± 0.96.1 ± 0.53073
35L15.2.12.6 ± 0.30.213.3 ± 0.95.2 ± 0.41498
36L15.2.22.7 ± 0.20.1212.3 ± 0.34.6 ± 0.33561
37L15.2.32.3 ± 0.20.1418.9 ± 0.98.4 ± 0.71617
38L15.2.46.5 ± 0.60.425.3 ± 1.43.9 ± 0.31284
39L15.2.52.9 ± 0.30.216.1 ± 0.85.6 ± 0.41322
40L15.2.61.69 ± 0.140.1213.6 ± 0.58.1 ± 0.65259
41L15.2.76.7 ± 0.70.658.2 ± 4.78.7 ± 0.63657
42L15.2.82.5 ± 0.40.414 ± 25.6 ± 0.41245
43L15.2.92.8 ± 0.60.612.8 ± 2.84.6 ± 0.3756
44L15.2.102.5 ± 0.20.1019.5 ± 0.37.7 ± 0.610969
45L15.2.124.2 ± 1.01.028.5 ± 6.66.8 ± 0.5903
46L15.2.131.8 ± 0.20.1312.1 ± 0.86.8 ± 0.52987
47L15.2.144.8 ± 0.60.531.5 ± 2.96.5 ± 0.5523
48L15.2.154.4 ± 0.30.226.2 ± 0.66.0 ± 0.412303
49L15.2.174.5 ± 0.50.423.9 ± 1.85.3 ± 0.41065
50L15.2.181.95 ± 0.20.210.9 ± 0.85.6 ± 0.44011
51L15.2.192.0 ± 0.20.1210.9 ± 0.35.4 ± 0.42620
52L15.2.203.0 ± 0.60.614.0 ± 2.64.7 ± 0.3956

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)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..

VERA#(ABA)

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

14C age(BP)Era andphaseCalibrated 2σBCE
PellaVERA 53112940 ± 35IAI-II1270–1020 BCE (94%)
PellaVERA 53012930 ± 35IAI-II1260–1010 BCE (91%)
PellaVERA 53162925 ± 35IAI-II1260–1010 BCE (95%)
PellaVERA 53102885 ± 35IAI-II1210–970 BCE (93%)

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)Observedbeta 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 standard972 ± 914.7 ± 0.7515 ± 10739.4 ± 1.666.7 ± 3.153.05 ± 0.963.9 ± 0.1
232Th standard9.36 ± 1.231792 ± 30571 ± 14878.56 ± 1.8461.3 ± 0.856.7 ± 1.92.4 ± 0.1
40K standard--13767 ± 9461.20 ± 161.20 ± 1-

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)
238U232Th40K238U232Th
L10.61.21 ± 0.020.137 ± 0.0061.13 ± 0.0522.9 ± 0.33.6 ± 0.2
L15.12.32 ± 0.040.182 ± 0.0081.51 ± 0.1244.1 ± 0.64.9 ± 0.3
L15.20.843 ± 0.0140.09 ± 0.010.79 ± 0.0516.1 ±0.22.5 ± 0.2
Fractional beta count rate contribution from each nuclide
238U232Th40KObserved average beta count rate (cks-1)
L10.60.45 ± 0.020.055 ± 0.0030.49 ± 0.03150 ± 2
L15.10.55 ± 0.030.045 ± 0.0050.41 ±0.05180 ± 3
L15.20.45 ± 0.020.054 ± 0.0050.5 ± 0.04198 ± 2

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

LayerNumber of acceptedsamplesAge average(ka)Random uncertainty(ka)Total uncertainty(ka)Over-dispersion(ka)Over-dispersion%
With outliers
L10.6112.790.130.240.2910.5
L15.1143.450.450.541.1436.1
L15.2133.320.490.511.2742.2
Without outliers
L10.6112.790.130.240.2910.5
L15.1133.020.210.300.7425.1
L15.2112.720.280.340.7528.6
Site Average Age
Including outliers383.200.200.301.033.8
Excluding outliers352.850.120.220.6624.1

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.

SampleObserved betacounts (cks-1)Beta doserate (Gy/ka)Alpha doserate (Gy/ka)
L10.6.1170 ± 22.98 ± 0.1028.83 ± 0.04
L10.6.2131 ± 22.30 ± 0.0822.32 ± 0.03
L10.6.3170 ± 22.98 ± 0.1028.90 ± 0.04
L10.6.4441 ± 37.7 ± 0.374.87 ± 0.09
L10.6.5168 ± 22.94 ± 0.1028.45 ± 0.04
L10.6.6156 ± 22.73 ± 0.0926.43 ± 0.04
L10.6.7153 ± 22.68 ± 0.0925.98 ± 0.03
L10.6.8139 ± 22.44 ± 0.0823.60 ± 0.03
L10.6.9142 ± 22.49 ± 0.0824.12 ± 0.03
L10.6.11105 ± 21.85 ± 0.0717.86 ± 0.02
L10.6.12183 ± 23.22 ± 0.1131.15 ± 0.04
L10.6.13177 ± 23.11 ± 0.1030.06 ± 0.04
L10.6.14123 ± 22.16 ± 0.0720.90 ± 0.03
L10.6.15136 ± 22.39 ± 0.0823.13 ± 0.03
L10.6.16168 ± 22.95 ± 0.1028.51 ± 0.04
L10.6.17217 ± 33.81 ± 0.1336.83 ± 0.05
L10.6.18156 ± 22.74 ± 0.1026.55 ± 0.04
L10.6.19106 ± 21.85 ± 0.0717.94 ± 0.03
L10.6.20131.6 ± 22.31 ± 0.0822.34 ± 0.03
L15.1.1192 ± 33.4 ± 0.237.64 ± 0.08
L15.1.2165 ± 32.9 ± 0.232.32 ± 0.07
L15.1.3188 ± 33.3 ± 0.236.89 ± 0.07
L15.1.4172 ± 33.1 ± 0.233.76 ± 0.07
L15.1.6177 ± 23.2 ± 0.234.8 ± 0.8
L15.1.7144 ± 22.55 ± 0.1428.17 ± 0.06
L15.1.8196 ± 23.5 ± 0.238.55 ± 0.08
L15.1.9172 ± 23.1 ± 0.233.68 ± 0.07
L15.1.10292 ± 35.2 ± 0.357.38 ± 0.11
L15.1.11219 ± 33.9 ± 0.243.03 ± 0.08
L15.1.12123 ± 22.19 ± 0.1224.18 ± 0.08
L15.1.13144 ± 22.56 ± 0.1428.30 ± 0.06
L15.1.14165 ± 22.9 ± 0.232.47 ± 0.06
L15.1.15177 ± 23.2 ± 0.234.81 ± 0.07
L15.1.16222 ± 23.9 ± 0.243.51 ± 0.08
L15.1.17172 ± 23.1 ± 0.233.72 ± 0.07
L15.1.18135 ± 22.41 ± 0.1326.58 ± 0.05
L15.1.19248 ± 34.4 ± 0.248.77 ± 0.09
L15.1.20169 ± 33.0 ± 0.233.18 ± 0.07
L15.2.1157 ± 22.76 ± 0.1126.79 ± 0.04
L15.2.2134 ± 22.34 ± 0.1022.74 ± 0.04
L15.2.3281 ± 34.9 ± 0.247.80 ± 0.07
L15.2.4108 ± 21.89 ± 0.0818.36 ± 0.03
L15.2.5179 ± 33.13 ± 0.1330.39 ± 0.05
L15.2.6264 ± 34.6 ± 0.244.97 ± 0.07
L15.2.7283 ± 35.0 ± 0.248.17 ± 0.05
L15.2.8176 ± 23.08 ± 0.1229.89 ± 0.05
L15.2.9133 ± 22.34 ± 0.1022.66 ± 0.04
L15.2.10259 ± 34.6 ± 0.244.15 ± 0.07
L15.2.12221 ± 23.9 ± 0.237.68 ± 0.06
L15.2.13211 ± 23.7 ± 0.235.98 ± 0.06
L15.2.14200 ± 23.50 ± 0.1434.00 ± 0.05
L15.2.15184 ± 23.23 ± 0.1331.35 ± 0.05
L15.2.17172 ± 23.01 ± 0.1229.25 ± 0.05
L15.2.18168 ± 22.94 ± 0.1228.54 ± 0.05
L15.2.19162 ± 22.84 ± 0.1127.55 ± 0.04
L15.2.20136 ± 22.39 ± 0.1023.21 ± 0.04
External dose rate
Soil samplesGamma dose rate (Gy/ka)238U (Bq/kg)232Th (Bq/kg)40K (Bq/kg)
L10.61.01 ± 0.12132 ± 3213.8 ± 1.6502 ± 25
L15.11.64 ± 0.15180 ± 2412.9 ± 1.3341 ± 21
L15.21.26 ± 0.11130 ± 2311.4 ± 1.8325 ± 24
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