Optical dating of sediments from manas lake in northwestern china: Paleoenvironmental and neotectonic implications
Publié en ligne: 05 oct. 2017
Pages: 175 - 187
Reçu: 31 janv. 2017
Accepté: 29 mars 2017
DOI: https://doi.org/10.1515/geochr-2015-0063
Mots clés
© 2017 Y.-Y. Tse and S.-H. Li
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
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The equivalent doses derived from the mean age model and the central age model, with the overdispersion values for the five samples.
| Sample ID | Number of aliquots 48 aliquots were measured for each sample. Aliquots were rejected by various reasons, including failure in recycling ratio test (4, 4, 4, 2, 2) or recuperation test (2, 1, 1, 1, 0), failure in fitting the dose response curve (0, 0, 0, 0, 2) and when the natural Lx/Tx cannot be interpolated onto the dose response curve (0, 3, 5, 2, 2). The five numbers in brackets refer to the number of aliquots rejected by that specific criteria for the five samples (MN15-1-1, 1-2, 1-3, 3-1, 3-2) respectively. | Mean age model De (Gy) | Central age model De (Gy) | Over-dispersion(%) |
|---|---|---|---|---|
| MN15-1-1 Due to insufficient bleaching problem, the minimum age model was used for the sample MN15-1-1, which gives a De of 2.67 ± 0.14 Gy. | 42 | 31.1 ± 5.9 | 16.3 ± 2.5 | 118 |
| MN15-1-2 | 40 | 219.8 ± 11.7 | 196.3 ± 8.3 | 22.5 |
| MN15-1-3 | 38 | 199.7 ± 8.6 | 186.5 ± 7.5 | 22.2 |
| MN15-3-1 | 43 | 183.9 ± 11.7 | 169.8 ± 10.0 | 38.0 |
| MN15-3-2 | 42 | 229.5 ± 11.2 | 216.9 ± 10.8 | 31.4 |
The single aliquot regenerative dose (SAR) protocol for quartz post-IR OSL measurements in this study.
| Step | Treatment | Observed |
|---|---|---|
| 1 | Give regenerative dose, Di For the ‘natural’ sample, i = 0 and D0 = 0. The whole sequence is repeated for several regenerative doses including a zero dose and a repeat dose. | |
| 2 | Preheat at 260°C / 220°C For the young sample MN15-1-1, the preheat was at 220°C and the cut-heat was at 180°C. For other samples, the preheat was at 260°C and the cut-heat was at 220°C. | |
| 3 | IR stimulation at 125°C for 100 s | |
| 4 | Blue light stimulation at 125°C for 40 s | Lx |
| 5 | Give test dose, DT | |
| 6 | Cut-heat at 220°C / 180°C For the young sample MN15-1-1, the preheat was at 220°C and the cut-heat was at 180°C. For other samples, the preheat was at 260°C and the cut-heat was at 220°C. | |
| 7 | IR stimulation at 125°C for 100 s | |
| 8 | Blue light stimulation at 125°C for 40 s | Tx |
| 9 | Blue light bleaching at 280°C for 100 s | |
| 10 | Return to step 1 | |
OSL dating results for the five samples in the study area.
| Sampling site | Sample ID | Grain size (µm) | Depth (cm) | α-count rate (cts/ks) The α-count rate is measured through a 42-mm-diameter ZnS screen. | K content (%) K content was measured using XRF. The error is assumed to be ±10% (relative). | Water content (%) The error in water content is estimated to be ±20% (relative). See text for discussion. | Cosmic ray (Gy/ka) The error in cosmic ray dose rate is assumed to be ±0.02 Gy/ka | Dose rate (Gy/ka) | Equivalent dose (Gy) Minimum age model is used for sample MN15-1-1 due to insufficient bleaching problem. Central age model (CAM) is used for other samples. | OSL age (ka) Minimum age model is used for sample MN15-1-1 due to insufficient bleaching problem. Central age model (CAM) is used for other samples. |
|---|---|---|---|---|---|---|---|---|---|---|
| Site 1 | MN15-1-1 | 180–212 | 22 | 4.97 ± 0.12 | 1.48 | 0.12 | 0.21 | 2.36 ± 0.11 | 2.67 ± 0.14 | 1.13 ± 0.08 |
| MN15-1-2 | 150–180 | 50 | 3.12 ± 0.10 | 1.64 | 1.9 | 0.20 | 2.22 ± 0.13 | 196.3 ± 8.3 | 88.5 ± 6.3 | |
| MN15-1-3 | 150–180 | 70 | 2.82 ± 0.09 | 2.03 | 10.6 | 0.20 | 2.32 ± 0.15 | 186.5 ± 7.5 | 80.3 ± 6.0 | |
| Site 3 | MN15-3-1 | 150–180 | 30 | 4.09 ± 0.12 | 2.20 | 25 | 0.21 | 2.32 ± 0.15 | 169.8 ± 10.0 | 73.3 ± 6.4 |
| MN15-3-2 | 125–150 | 90 | 7.71 ± 0.17 | 2.17 | 25 | 0.19 | 2.71 ± 0.16 | 216.9 ± 10.8 | 80.2 ± 6.1 |