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Details of modern samples_ Equivalent doses (De) were determined from IR50, pIRIR150, and pIRIR290_
| Site | Lab code | Latitude | Longitude | Water depth (m) | De from IR50 (Gy) | De from pIRIR150 (Gy) | De from pIRIR290 (Gy) |
|---|---|---|---|---|---|---|---|
| Katakai | gsj15160 | N35°32′28.2″ | E140°27′55.8″ | 0 | 0.09 ± 0.01 | 0.93 ± 0.08 | 11.93 ± 1.66 |
| BS9 | gsj17282 | N35°37′42.1″ | E140°37′13.9″ | 13 | 0.04 ± 0.01 | 1.80 ± 0.16 | 27.28 ± 1.08 |
| BS10 | gsj17283 | N35°37′42.3″ | E140°40′16.6″ | 14 | 0.07 ± 0.003 | 2.45 ± 0.13 | 29.09 ± 1.44 |
| BS23 | gsj17284 | N35°35′11.9″ | E140°41′48.5″ | 23 | 0.18 ± 0.01 | 3.25 ± 0.33 | 29.27 ± 1.47 |
| BS34 | gsj17273 | N35°32′40.0″ | E140°45′39.4″ | 34 | 0.06 ± 0.01 | 2.26 ± 0.14 | 23.92 ± 1.60 |
Details of Holocene samples taken from drill cores: sample level, water, U, Th, K, and Rb contents, estimated dose rates, and expected ages from radiocarbon dates_ The internal dose rate was estimated to be 0_738±0_123 Gy/ka for all samples_
| Lab code | Depth (m) | Water content (%) | U (ppm) | Th (ppm) | K (%) | Rb (ppm) | Cosmic dose rate (Gy/ka) | Total dose rate (Gy/ka) | Expected age (ka) |
|---|---|---|---|---|---|---|---|---|---|
| GSJ-QAS2 (N35°43′17.3″ E140°37′52.0″ Elevation: +5.2 m) | |||||||||
| gsj15149 | 2.2 | 21 | 0.67 | 2.9 | 1.1 | 39 | 0.15 ± 0.02 | 2.07 ± 0.14 | 5.89 ± 0.08 |
| gsj15151 | 4.2 | 31 | 0.89 | 3.6 | 1.3 | 48 | 0.12 ± 0.01 | 2.17 ± 0.14 | 6.01 ± 0.08 |
| gsj15154 | 7.5 | 20 | 0.7 | 3.0 | 1.4 | 55 | 0.09 ± 0.01 | 2.28 ± 0.14 | 6.26 ± 0.08 |
| gsj15155 | 10.2 | 39 | 1.1 | 4.3 | 1.6 | 62 | 0.07 ± 0.01 | 2.26 ± 0.14 | 6.88 ± 0.08 |
| gsj15157 | 14.4 | 34 | 0.89 | 3.8 | 1.6 | 60 | 0.05 ± 0.01 | 2.28 ± 0.14 | 7.13 ± 0.08 |
| gsj15158 | 14.8 | 42 | 1.2 | 3.8 | 1.6 | 62 | 0.05 ± 0.00 | 2.21 ± 0.14 | 7.15 ± 0.08 |
| GSJ-QYH1 (N35°37′00.0″ E140°32′29.2″ Elevation: +2.1 m) | |||||||||
| gsj15254 | 2.3 | 20 | 0.91 | 4.8 | 0.97 | 34 | 0.15 ± 0.02 | 2.13 ± 0.14 | 0.23 ± 0.08 |
| gsj15255 | 4.9 | 33 | 0.88 | 3.1 | 1.6 | 58 | 0.11 ± 0.01 | 2.30 ± 0.14 | 0.45 ± 0.08 |
| gsj15256 | 7.2 | 30 | 0.67 | 3.3 | 1.5 | 52 | 0.09 ± 0.01 | 2.23 ± 0.14 | 0.66 ± 0.08 |
| gsj15257 | 10.7 | 33 | 0.76 | 4.0 | 1.5 | 50 | 0.06 ± 0.01 | 2.16 ± 0.14 | 1.13 ± 0.08 |
| gsj15258 | 14.6 | 31 | 0.73 | 3.1 | 1.6 | 50 | 0.05 ± 0.01 | 2.21 ± 0.14 | 1.74 ± 0.08 |
| sj15259 | 19.2 | 31 | 0.8 | 3.5 | 1.6 | 51 | 0.03 ± 0.00 | 2.24 ± 0.14 | 2.44 ± 0.08 |
Equivalent dose (De), uncorrected age, g-value, corrected age, offset from expected age, and De offset from expected for pIRIR150 signals of Holocene samples_
| Lab code | Depth (m) | De (Gy) | Uncorrected age (ka) | g-value (%/decade) | Corrected age (ka) | Age offset from expected (ka) | De offset from expected (Gy) |
|---|---|---|---|---|---|---|---|
| GS-QAS-2 | |||||||
| gsj15149 | 2.2 | 22.83 ± 1.25 | 11.0 ± 0.9 | 1.13 ± 0.17 | 12.0 ± 1.2 | 6.1 ± 1.2 | 12.64 ± 0.16 |
| gsj15151 | 4.2 | 34.00 ± 1.51 | 15.7 ± 1.2 | 1.28 ± 0.09* | 17.3 ± 1.3 | 11.3 ± 1.3 | 24.46 ± 0.18 |
| gsj15154 | 7.5 | 28.50 ± 1.17 | 12.5 ± 0.9 | 1.16 ± 0.08 | 13.7 ± 1.0 | 7.4 ± 1.0 | 16.88 ± 0.15 |
| gsj15155 | 10.2 | 40.57 ± 1.17 | 17.9 ± 1.2 | 1.28 ± 0.09* | 19.8 ± 1.3 | 12.9 ± 1.3 | 29.21 ± 0.18 |
| gsj15157 | 14.4 | 39.51 ± 1.36 | 17.3 ± 1.2 | 1.28 ± 0.09* | 19.2 ± 1.3 | 12.0 ± 1.3 | 27.40 ± 0.19 |
| gsj15158 | 14.8 | 39.62 ± 1.03 | 17.9 ± 1.2 | 1.28 ± 0.09* | 19.8 ± 1.3 | 12.7 ± 1.3 | 27.95 ± 0.18 |
| GS-QYH-1 | |||||||
| gsj15254 | 2.3 | 18.08 ± 0.60 | 8.5 ± 0.6 | 1.45 ± 0.37 | 9.4 ± 0.7 | 9.2 ± 0.7 | 19.58 ± 0.10 |
| gsj15255 | 4.9 | 26.42 ± 1.38 | 11.5 ± 0.9 | 1.11 ± 0.16 | 12.5 ± 0.9 | 12.0 ± 0.9 | 27.69 ± 0.12 |
| gsj15256 | 7.2 | 21.50 ± 0.85 | 9.6 ± 0.7 | 1.05 ± 0.32 | 10.4 ± 0.7 | 9.8 ± 0.7 | 21.78 ± 0.10 |
| gsj15257 | 10.7 | 28.89 ± 0.79 | 13.4 ± 0.9 | 1.07 ± 0.12 | 14.5 ± 1.0 | 13.3 ± 1.0 | 28.85 ± 0.14 |
| gsj15258 | 14.6 | 26.99 ± 1.02 | 12.2 ± 0.9 | 1.96 ± 0.36 | 14.3 ± 1.2 | 12.6 ± 1.2 | 27.81 ± 0.17 |
| gsj15259 | 19.2 | 25.46 ± 0.64 | 11.4 ± 0.8 | 1.31 ± 0.18 | 12.5 ± 0.9 | 10.1 ± 0.9 | 22.66 ± 0.13 |
Radiocarbon dating results for drill core samples_
| Access code | Core depth (m) | Sample | Conventional 14C age (yr BP) | Calibrated age (2s) (cal yr BP) | Probability |
|---|---|---|---|---|---|
| GS-QAS-2 | |||||
| IAAA-153551 | 7.3 | Shell (Mactra chinensis) | 5720 ± 30 | 6019–6239 | 1.000 |
| IAAA-153282 | 9.1 | Shell (M. chinensis) | 6290 ± 30 | 6653–6843 | 1.000 |
| IAAA-153552 | 21.3 | Shell (Raetellops pulchellus) | 6970 ± 30 | 7411–7540 | 1.000 |
| IAAA-153283 | 25.4 | Shell (R. pulchellus) | 7850 ± 30 | 8224–8388 | 1.000 |
| IAAA-153284 | 38.9 | Shell (Glossaulax didyma) | 8950 ± 30 | 9511–9708 | 1.000 |
| IAAA-153553 | 41.8 | Shell (Dosinia angulosa) | 9570 ± 40 | 10295–10551 | 1.000 |
| IAAA-151461 | 43.6 | Plant fragment | 9700 ± 40 | 10878–10933 | 0.097 |
| 11080–11212 | 0.903 | ||||
| GS-QYH-1 | |||||
| IAAA-153560 | 3.4 | Shell (Chion semigranosa) | 620 ± 20 | 146–164 | 0.026 |
| 187–312 | 0.974 | ||||
| IAAA-153288 | 8.4 | Shell (M. chinensis) | 1150 ± 20 | 649–749 | 1.000 |
| IAAA-153561 | 19.1 | Shell (Siliqua pulchella) | 2680 ± 30 | 2303–2456 | 1.000 |
| IAAA-153289 | 25.8 | Shell (R. pulchellus) | 7220 ± 30 | 7596–7761 | 1.000 |
| IAAA-153562 | 27.3 | Shell (Macoma tokyoensis) | 8020 ± 30 | 8393–8556 | 1.000 |
| IAAA-153290 | 32.4 | Shell (Dentalium octangulatum) | 9010 ± 40 | 9540–9822 | 1.000 |
Summaries of the IR50, pIRIR150, and pIRIR290 single-aliquot regenerative dose protocols used in this study_
| Step | post-IR IRSL (150°C) | Signal | post-IR IRSL (290°C) | Signal |
|---|---|---|---|---|
| 1 | Preheat at 180°C for 60 s | Preheat at 320°C for 60 s | ||
| 2 | IR stimulation at 50°C for 100 s | Lx for IRSL50 | IR stimulation at 50°C for 200 s | |
| 3 | IR stimulation at 150°C for 100 s | Lx for post-IR IRSL150 | IR stimulation at 290°C for 200 s | Lx for post-IR IRSL290 |
| 4 | Test dose | Test dose | ||
| 5 | Preheat at 180°C for 60 s | Preheat at 320°C for 60 s | ||
| 6 | IR stimulation at 50°C for 100 s | Tx for IRSL50 | IR stimulation at 50°C for 200 s | |
| 7 | IR stimulation at 150°C for 100 s | Tx for post-IR IRSL150 | IR stimulation at 290°C for 200 s | Tx for post-IR IRSL290 |
| 8 | Dose and return to step 1 | IR stimulation at 325°C for 200 s | ||
| 9 | Dose and return to step 1 |
Equivalent dose (De), uncorrected age, g-value, corrected age, offset from expected age, and De offset from expected for IR50 signals of Holocene samples_
| Lab code | Depth (m) | De (Gy) | Uncorrected age (ka) | g-value (%/decade) | Corrected age (ka) | Age offset from expected (ka) | De offset from expected (Gy) |
|---|---|---|---|---|---|---|---|
| GS-QAS-2 | |||||||
| gsj15149 | 2.2 | 5.25 ± 0.09 | 2.5 ± 0.2 | 8.48 ± 0.73 | 5.8 ± 1.0 | −0.1 ± 1.0 | −0.17 ± 0.14 |
| gsj15151 | 4.2 | 6.78 ± 0.11 | 3.1 ± 0.2 | 7.96 ± 0.15* | 6.8 ± 0.5 | 0.8 ± 0.5 | 1.6 ± 0.07 |
| gsj15154 | 7.5 | 7.64 ± 0.20 | 3.4 ± 0.2 | 7.51 ± 0.45 | 6.9 ± 0.8 | 0.6 ± 0.8 | 1.5 ± 0.11 |
| gsj15155 | 10.2 | 7.89 ± 0.13 | 3.5 ± 0.2 | 7.96 ± 0.15* | 7.6 ± 0.5 | 0.7 ± 0.5 | 1.6 ± 0.07 |
| gsj15157 | 14.4 | 8.10 ± 0.09 | 3.6 ± 0.2 | 7.96 ± 0.15* | 7.8 ± 0.6 | 0.6 ± 0.6 | 1.5 ± 0.09 |
| gsj15158 | 14.8 | 7.82 ± 0.11 | 3.5 ± 0.2 | 7.96 ± 0.15* | 7.7 ± 0.6 | 0.6 ± 0.6 | 1.3 ± 0.08 |
| GS-QYH-1 | |||||||
| gsj15254 | 2.3 | 0.28 ± 0.01 | 0.13 ± 0.01 | 8.21 ± 0.42 | 0.2 ± 0.0 | 0.0 ± 0.1 | 0.01 ± 0.01 |
| gsj15255 | 4.9 | 0.40 ± 0.01 | 0.18 ± 0.01 | 8.26 ± 0.28 | 0.3 ± 0.0 | −0.1 ± 0.1 | −0.29 ± 0.01 |
| gsj15256 | 7.2 | 0.67 ± 0.02 | 0.30 ± 0.02 | 7.39 ± 0.10 | 0.5 ± 0.0 | −0.1 ± 0.1 | −0.27 ± 0.01 |
| gsj15257 | 10.7 | 1.46 ± 0.03 | 0.68 ± 0.05 | 8.93 ± 0.90 | 1.5 ± 0.3 | 0.4 ± 0.3 | 0.77 ± 0.04 |
| gsj15258 | 14.6 | 1.95 ± 0.02 | 0.88 ± 0.06 | 7.20 ± 0.13 | 1.6 ± 0.1 | −0.1 ± 0.1 | −0.26 ± 0.02 |
| gsj15259 | 19.2 | 2.49 ± 0.03 | 1.1 ± 0.1 | 7.73 ± 0.73 | 2.2 ± 0.3 | −0.3 ± 0.3 | −0.57 ± 0.05 |