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1.
对来自新疆昆仑山北坡于田克里雅河-皮山县一带的4个风成样品的细颗粒石英进行了热转移光释光法（TT-OSL）测试,以探讨该方法应用于该区域风成沉积测年的可行性。测试结果表明,这4个样品的TT-OSL信号均十分微弱,信噪比偏低,致使感量校正后的天然和再生剂量TT-OSL信号强度点散乱,难以拟合出高质量和高可靠性的生长曲线,因而也很难计算出一个可靠的De值。经研究后初步认为,TT-OSL法无法对新疆昆仑山北坡风成堆积物进行可靠的测年。 相似文献
2.
The Sima del Elefante site is located within the Sierra de Atapuerca karst system (Burgos, northern Spain), and forms part of a series of important Early, Middle and Late Pleistocene archaeological complexes that have been dated previously with luminescence techniques (Gran Dolina, Galería Complex, Sima de los Huesos, Galería de las Estatuas). This study focuses on the upper Middle Pleistocene units (TE18 and TE19) at Sima del Elefante, which contain Acheulean and transitional lithic assemblages (Mode 2/3), as well as large and small mammal fossils. Importantly, these uppermost units are associated with a sediment plug located in the cave's interior at Galería Baja, which marks the closure of a significant palaeoentrance to the Atapuerca karst system. Establishing the accumulation history of these related deposits is important for understanding both Lower Palaeolithic technological dynamics via comparisons with similar levels at other Atapuerca sites (i.e., Gran Dolina and Galería Complex), as well as past human occupation patterns and carnivore use of (and accessibility to) the caves. We present single-grain TT-OSL and multi-grain pIR-IR chronologies for the Sima del Elefante upper sequence and the Galería Baja sediment cone, as well as U-series dating results for a stalagmitic crust capping the combined clastic infill sequence. The paired luminescence ages for the upper occupation levels are in agreement with each other and reveal that the host deposits accumulated 576–481 ka for the TE18 stratified scree layers, 266–237 ka for TE19 and 206–250 ka for the Galería Baja upper cone section (weighted mean 2σ age ranges). A concordant U-series age of 202 ± 65 ka is obtained for the overlying stalagmitic crust at Galería Baja. The Sima del Elefante ages are consistent with those previously obtained using U-series and biochronology, confirming that there is an erosional unconformity and complex carbonate deposition phase associated with the upper layers of unit TE18 and that the original cave entrance likely closed by ∼200 ka. Chronological correlation with other Atapuerca sites reveals potential equivalence between TE18 and unit TD8 (at Gran Dolina), and between TE19 and units GIIb–GIIIb (at Galería Complex) and, possibly, TD10.1 and TD10.2 (at Gran Dolina), though more refined dating is required to confirm the latter. 相似文献
3.
This study presents palaeodosimetric results from the Middle Pleistocene archaeological site of Coudoulous I (Lot, SW France). Nine sedimentary quartz samples (41–60 μm) have been analyzed using a multiple aliquot protocol based on the measurement of the TT-OSL signal. In addition, 7 teeth and 7 bones have been dated by combining the ESR method with U-series analyses. Both methods gave consistent age results allowing correlation of the Early Middle Paleolithic Human occupation of the site to MIS 6 and part of the Lower Paleolithic tools to MIS 7. Beyond the establishment of a radiometric chronology for the Coudoulous I sequence, this study focuses on the information extracted from the intercomparison of the methods. Our data suggest that 1) the TT-OSL signal is stable over at least the last 230 ka (considering the age range of the studied samples), 2) there are not significant problems of incomplete bleaching leading support to the applicability of the TT-OSL technique for sedimentary deposits associated with karstic contexts. This approach highlights the interest of combining luminescence and ESR/U-series methods to discuss the reliability of the dating results. 相似文献
4.
We present the results of a combined Electron Spin Resonance (ESR) and Luminescence dating study for the lowermost stratigraphic unit (TD1) of the palaeoanthropological site of Atapuerca Gran Dolina, Spain. Ten samples collected through the Main Section were dated using either the Multiple Centre (MC) ESR approach or the single-grain thermally transferred optically stimulated luminescence (SG TT-OSL) technique, both of which were applied to quartz grains. The two methods yield consistent ages, providing a robust chronostratigraphic framework for the TD1 deposits and enabling improved correlation of the magnetostratigraphic succession (comprising three intervals of normal polarity; N1 to N3, from bottom to top) with the Geomagnetic Polarity Time Scale. Specifically, the results provide a late Early Pleistocene chronology for TD1, and clearly position the deposits in the post-Olduvai time range (<1.77 Ma). The final age estimates range from 1.30 ± 0.14 Ma (TT-OSL) close to the bottom of the section to a mean ESR age of 1.05 ± 0.12 Ma (1 s.d.) for three samples from the N3 interval towards the top. Consequently, the N3 interval may confidently be correlated to the Jaramillo Subchron, while we propose a correlation of N1 and N2 with the Cobb Mountain subchron and Punaruu excursion, respectively; although we cannot exclude that these two normal intervals may correspond to other, unknown, geomagnetic events given the existing uncertainties associated with the ESR and luminescence ages.From a methodological point of view, the ESR MC approach shows that the Titanium signal provides the most reliable burial ages for TD1. In contrast, the Aluminium centre yields systematically overestimated age estimates, as a result of incomplete resetting of the signal before sediment deposition. The SG TT-OSL ages presented here are amongst the oldest published so far, and highlight the potential of the high temperature SG TT-OSL290 approach for obtaining finite ages exceeding 1 Ma at Atapuerca.Finally, these new dating results provide key insights into the rates and nature of sedimentary processes at Gran Dolina, modifying long-standing interpretations of the cave formation and infilling dynamics. An age of at least 1.4 Ma may be inferred for the base of the sedimentary infill at the Main Section, providing minimum age constraint for the formation of the cavity and, by extension, for the intermediate level of the Atapuerca karst. The opening of the cave, which pre-dates human occupation, most likely occurred close to or slightly after 0.9 Ma. This suggests that both TD4 and TD6 archaeological levels were deposited within a relatively short time range of <100 kyr. The so-called autochthonous fluvial deposits from TD1 unit, or at least those dated in the present study, were also clearly primarily derived from outside the karst system, and were not reworked from older deposits within the karst. They experienced sufficient daylight exposure and minimum transport times within the karst system to enable consistency between the ESR and TT-OSL burial ages and the independent magnetostratigraphic evidence. Our results highlight the need to reconsider the terminology traditionally employed to differentiate the two main phases of Gran Dolina's sedimentary infill. 相似文献
5.
使用一种新的光释光测年法——热转移光释光（TT-OSL）法对甘孜县城附近的甘孜-A剖面上的黄土细颗粒石英进行实验测试,以探讨该方法用于其测年的可行性.实验测试结果表明,样品的天然回授OSL （ReOSL）信号强度随地层深度增加而增大,表现出明显的积累.利用“替换点”分析方式对TT-OSL法的检验表明该方法能够用于甘孜黄土的测年.采用简单多片法（SMAR）和TT-OSL法分别对3个样品进行等效剂量（De）测试及年龄计算,结果显示TT-OSL法得到的De值及年龄明显大于简单多片法,但TT-OSL法年龄与前人磁性地层研究中的期望年龄相差比较大.研究初步认为,TT-OSL法可以对甘孜黄土进行测年,但是结果的可靠性还需要有更多的可信独立年龄验证. 相似文献
6.
Single-grain thermally transferred optically stimulated luminescence (TT-OSL) dating has recently been applied to a number of the Atapuerca palaeoanthropological sites. As yet, however, there have not been any direct assessments of TT-OSL signal stabilities for specific grains used for dating. In this study, we undertake a series of TT-OSL suitability assessments on known-age samples from Gran Dolina and Sima del Elefante. Our results suggest that the Atapuerca samples contain populations or sub-populations of grains with suitably stable TT-OSL signals for dating over late-Early and Middle Pleistocene timescales. Equivalent dose (De) distribution analysis in combination with pulse-annealing assessments provides a useful means of identifying inter-grain and inter-sample differences in TT-OSL signal stabilities. We also show that obtaining De values using different preheat conditions may help to identify potentially problematic TT-OSL behaviours. Analyses of multi-grain aliquot TL curves for these samples reveal that 'bulk' TL signal loss experiments may provide limited insights into TT-OSL source trap lifetimes due to averaging effects, the dominance of grain populations that do not produce TT-OSL, and interference from slowly bleaching OSL components. Our results improve the robustness and precision of existing TT-OSL chronologies for units TD6-3 and TE16-TE17 at Gran Dolina and Sima del Elefante, and support the broader suitability of the single-grain TT-OSL approach at the Atapuerca sites. 相似文献
7.
通过对滹沱河冲洪积物、阳原盆地湖相地层细颗粒石英天然热转移光释光(TT-OSL)信号测量、回授剂量恢复测试以及简单多片光释光(OSL)与回授光释光(Re-OSL)测量结果对比等,探讨了细颗粒石英回授光释光在水成沉积物测年中应用的可能性。结果表明,冲积样品回授光释光信号没有随深度逐步增加的规律,而湖相样品热转移光释光信号随深度逐渐增大;冲洪积物细颗粒石英样品回授光释光不能得出剂量值,剂量不能恢复;而湖相样品回授实验室附加剂量与测得的剂量在2%的误差范围内一致,说明回授光释光测年在一定时间范围内对于湖相样品测年是可行的;细颗粒石英回授释光在测量>10万a的湖相样品年龄方面具有很大的潜力 相似文献
8.
Relatively little is known about the long-term sediment accumulation dynamics of Naracoorte Cave Complex (NCC) solution pipe cavities, and many of the megafauna-bearing infill deposits at this globally significant Australian Pleistocene fossil locality remain partially dated or lack any numerical age control. In this study, we assess the suitability of three different luminescence dating signals for improving existing chronologies at six Late and Middle Pleistocene NCC sites (n = 22 samples), and we undertake multi-site examinations of NCC sediment infill dynamics spanning the last 550 thousand years (ka). Modern analogue samples collected from above and beneath two active cave entrances confirm that single-grain OSL, single-grain TT-OSL and multi-grain pIR-IRSL signals can be reset down to insignificant residual levels (<10−1–100 Gy) when compared with the natural dose ranges of interest for most NCC palaeontological applications. Replicate luminescence dating comparisons performed at six NCC fossil sites (n = 15 samples) reveal consistent ages for twenty-eight out of thirty-one paired OSL–TT-OSL, OSL–pIR-IRSL and TT-OSL–pIR-IRSL datasets. Nineteen of the twenty Middle to Late Pleistocene samples analysed from the NCC sites produce homogeneous OSL, TT-OSL and pIR-IRSL De datasets suggesting that the NCC solution pipe deposits considered here are generally not affected by syn-depositional mixing complications that can take place within closed karst cavities (i.e., the remobilisation of unbleached grains from pre-existing cave floor sediments, and their subsequent translocation and incorporation into deposits within deeper parts of the cavity along with externally bleached, allochthonous grain populations). Detailed examination of solution pipe dynamics at Smoke Tortoise Cave (SMT) reveals a complex accumulation history focused on the marine isotope stage (MIS) 9 and MIS 7 interglacial complexes, as well as the MIS 8e interstadial. The SMT case study highlights that NCC solution pipes are not simply associated with short-lived opening and sediment accumulation events, but may involve multiple, discontinuous deposition episodes and reactivation events. An initial multi-site examination of all published NCC infill chronologies (n = 70) appears to suggest statistically significant, preferential solution pipe development during the relatively wet parts of interglacial or interstadial cycles. The non-uniform infill age distribution implies that NCC solution pipe dynamics may have exerted taphonomic biases on fossil accumulation, which should be taken into consideration when reconstructing long-term palaeoecological histories from NCC solution pipe cavities. 相似文献
9.
Zenobia Jacobs Richard G. Roberts Terry J. Lachlan Panagiotis Karkanas Curtis W. Marean David L. Roberts 《Quaternary Geochronology》2011,6(5):491-513
Optically stimulated luminescence (OSL) dating is now commonly used to estimate the depositional age of Quaternary landforms along the southern Cape coast of South Africa. Due to the early onset of dose saturation in the quartz-rich sediments from this region, determining the age of deposits much older than the last three glacio-eustatic sea-level high stands has been a challenge. In this study, we explored the feasibility of using the thermally-transferred OSL (TT-OSL) dating method to obtain ages for aeolian and shallow marine deposits at three different localities that hold promise to further illuminate the long and complex Late Quaternary sea-level history of this region. The bleachability and behaviour of both the recuperated OSL (ReOSL) and the basic-transferred OSL (BT-OSL) signals were investigated, and used as independent chronometers to infer (a) the degree of bleaching of the sediments and (b) the stability of the ReOSL signal for dating of older samples. We examined the sensitivity of both signals to varying preheat temperatures and further developed the single-aliquot regenerative-dose procedure for TT-OSL dating of our samples. To verify our procedures, and to understand some of the underlying mechanisms responsible for the problems we observed, modern analogues and known-age Marine Isotope Sub-stage (MIS) 5e samples from the same localities were also measured. The Middle Pleistocene deposits investigated in this study produced statistically consistent ReOSL and BT-OSL ages compatible with sea-level high stands during Marine Isotope Stage 11. This result is of considerable significance, as it may yield new insights into maximum sea-level heights during this period, which is widely considered an appropriate analogue for future environmental conditions. 相似文献
10.
The paleogeography of Amazonia lowlands during the Pleistocene remains hampered by the lack of reliable absolute ages to constrain sediment deposition in the hundred thousand to few million years timescales. Optically stimulated luminescence (OSL) dating applied to quartz has provided important chronological control for late Quaternary sediments, but the method is limited to the last ∼150 ka. In order to extend the age range of luminescence dating, new signals from quartz have been investigated. This study tested the application of isothermal thermoluminescence (ITL) and thermally transferred optically stimulated luminescence (TT-OSL) signals of quartz for dating of fluvial terraces from eastern Amazonia. ITL and TT-OSL signals measured in a modern fluvial sediment sample have shown small residual doses (4 and 16 Gy), suggesting adequate bleached sediments for the target dose range (>150 Gy). This sample responded well to dose recovery test, which showed that the ITL and TT-OSL signals grow to higher doses compared to the doses estimated by the conventional OSL signal. The ITL signal saturated for doses significantly lower than doses reported in the literature. Most dating samples were beyond the ITL saturation doses and only TT-OSL signals were suitable to estimate equivalent doses. Burial ages ranging from 107 to 340 ka were estimated for the fluvial terraces in the lower Xingu River. The main ages uncertainties are related to dose rate changes through time. Despite the uncertainties, these ages should indicate a higher channel base level during the Middle Pleistocene followed by channel incision, possibly due to episodes of increased precipitation in the Xingu watershed. 相似文献