Quaternary Geochronology最新文献

The Guxiang Glaciation, a key reference for classifying late Quaternary glaciations on the Tibetan Plateau, has been dated to MIS 6 using cosmogenic ¹⁰Be exposure dating of two boulders. However, additional dating methods are needed to evaluate and improve its chronology. In this study, we used the post-infrared infrared stimulated luminescence (post-IR IRSL) signal at 225 °C from single K-feldspar grains to date a lateral moraine corresponding to the Guxiang Glaciation in the Bodui Zangbo Valley, southeastern Tibetan Plateau. Six samples from glaciofluvial sand lenses interbedded within the moraine were analyzed. The L_nT_n method was utilized for D_e determination to avoid truncation in D_e distribution and age underestimation. A common standardized growth curve (SGC) was established for all samples, and the least-squares (LS)-normalized L_n/T_n values of the brightest grains were selected for L_n/T_n and D_e estimation using the central age model (CAM). Using one fading-correction model, the post-IR IRSL ages (159 ± 9 ka to 181 ± 11 ka, average value of 173 ± 4 ka) fall within the expected MIS 6 interval and align with previous ¹⁰Be exposure ages. However, the ages are close to the limit of the method, and a different model for correcting fading suggests a much older age (average 308 ± 27 ka). This study reveals both the potential and challenges of single-grain K-feldspar luminescence dating as a means to establish chronological control for glaciations beyond the last glacial period on the Tibetan Plateau.

Single-grain OSL dating of quartz is a popular approach to OSL dating, even when incomplete bleaching is not likely to be significant. However, little testing of the accuracy of single-grain dating has been published; particularly for samples older than 50 ka. In this study, we investigate the accuracy of single-grain quartz OSL dating, when a significant number of individual grains are no longer able to accurately measure the burial dose because of saturation effects. We compare standard multi-grain OSL results with those obtained from single-grain OSL measurements for five OIS substage 5e (Eemian) samples (∼128 ka). We show that for these samples, standard multi-grain quartz dose estimation results in dose estimates in good agreement with the predicted doses (four of the five samples recover age control), but that standard frequentist single-grain dating procedures significantly underestimate the age controls, i.e. the measured to predicted dose range between 0.42 ± 0.03 and 0.84 ± 0.06, where the underestimation increases with increasing relative number of grains in saturation. Attempting to remove the inevitable bias in the dose estimation resulting from a significant number of saturated grains (by using the D_c criterion) reduced the underestimation, i.e. the measured to predicted dose ratio range between 0.63 ± 0.05 and 0.94 ± 0.08, but only the sample with the smallest absorbed dose is consistent with the age control. Using Bayesian analysis (“BayLum”) the ratio of measured to predicted dose range between 0.75 ± 0.07 and 1.14 ± 0.08, but only two of the five samples agree with the independent age control. Our results have implications for the evaluation of single-grain OSL dating of quartz in the 100–200 Gy natural dose range.

The Paleolithic site of Kalinga, in the Cagayan River Basin (Luzon Island), has recorded the oldest known traces of human occupation of the Philippine archipelago dated at 709 ± 68 ka. The island of Luzon is further known for its endemic Hominin Homo luzonensis (Callao cave) recently dated at 134 ± 14 ka, which makes it the oldest human remains in the Philippines.

The present study provides new chronological data on the Kalinga site and surrounding localities on the left bank of the Cagayan Valley and tackles the question over the geochronology of the human settlement of the basin. Following the discovery of some abundant paleontological remains and lithic artefacts on surface, several excavations took place since the 1970s. In 2014, new research in the area by our team on a site named Kalinga led to the recovery of hundreds of undisturbed archaeological remains (lithic tools and butchery marks). Apart from the early Middle Pleistocene ages obtained for the Kalinga site, the geochronology of the area is still largely unknown. Through the use of ESR on bleached quartz and ⁴⁰Ar/³⁹Ar single crystal laser fusion on plagioclase dating methods, the chronology of four archaeological sequences has been here constrained for the first time. Our results highlight a human occupation presence between 796 ± 70 ka and 273 ± 20 ka reducing the chronological gap between Kalinga site and Callao Cave, placing the Cagayan basin as a cornerstone to better understand the human arrival in insular Asia.

Located in the interior of the Tibetan Plateau (TP) and at the headwaters of the Yangtze River, the Damqu Wetland ranks among the world's highest and is highly sensitive to global climate change. Due to its remoteness and harsh, uninhabitable conditions, the sedimentological and geomorphological studies are still absent by far. Establishing a reliable chronology for sediments is crucial for this unique geographic region. Here we initiated this effort and focused on two riverbank profiles, located in the southeastern of the alpine Damqu Wetland, DQ1 (4.8 m in depth) and DQ2 (3.3 m in depth). A combination of chronological methods, including quartz Optically Stimulated Luminescence (OSL), K-feldspar post-IR InfraRed Stimulated Luminescence (pIRIR), and radiocarbon dating methods, as well as magnetic susceptibility and particle size analysis, were conducted on these profiles to establish the depositional history and reveal the palaeoenvironmental conditions of the Damqu Wetland. The dating results indicate that profiles DQ1 and DQ2 were deposited during ∼59–0.20 ka and ∼265–1.12 ka, respectively. It is interesting to note that the D₀ of quartz OSL growth curve has a value as high as 129 Gy. Both profiles exhibit depositional hiatuses, with time gaps between 37 ± 2 and 2.9 ± 0.2 ka for DQ1 and between 265 ± 16 and 4.8 ± 0.4 ka for DQ2, likely due to fluvial erosion during the period of from deglaciation to middle Holocene. The resumed sediment accumulation since the mid-late Holocene is probably mainly attributed to declined fluvial erosion in response to reduced rainfall. The darker sediment layers at depths of 0.9 m–0.7 m and 0.3 m–0.1 m in DQ2, combined with magnetic susceptibility and particle size analyses results, suggest two regional climatic optimum periods at around 4.5 ka and 1 ka. Overall, our research establishes the chronological framework of the Damqu wetland since the Late Quaternary and highlights the significant impact of climate changes on fluvial processes and wetland evolution in the remote interior TP.

Sediments of the Lena River represent an important environmental archive for understanding the Quaternary history of North-Eastern Siberia. However, at present, the structure, origin and age of the Lena River terraces are poorly known. This article presents results of lithofacies analysis and absolute dating of the Ust’-Buotama section exposing the fourth (Bestyakh) terrace of the Lena River. We report the first quartz and K-feldspar luminescence ages, the reliability of which was argued by age relations and standard tests. Three stratigraphic units have been recognized in the section (depths from the top): lacustrine-alluvial deposits (85–120 m) of the Mavrinka Formation; aeolian sand deposits of the Dolkuma Formation (23–85 m), and Holocene aeolian dune sediments (0–23 m). The resulting chronology suggests that the sediments of the Mavrinka Formation were deposited no later than 300 ka (MIS 9 or later). Deposition of the Dolkuma Formation occurred from ∼30 ka to ∼15 ka (late MIS 3 - late MIS 2). Holocene aeolian dune formed during initial Neoglacial cooling post climatic optimum (c. 5.5 cal ka BP). More extensive Late Holocene dune sediments which formed ∼400 years ago are coeval with Little Ice Age (11th-19th centuries).

The aeolian sediments in the Central Shandong Mountains (CSM) in eastern China provide a faithful carrier of climate and sea-level variations outside of the Chinese Loess Plateau. However, due to the lack of or limited application of absolute dating protocols, previous studies of Shandong loess have focused mainly on loess deposited since the last interglacial period, with fewer studies on provenances and climate changes recorded in older penultimate interglacial period characterized by a long duration and significant climate fluctuations, which is not helpful to understand the spatiotemporal pattern changes of East Asian monsoon. In this study, multi-elevated-temperature post-infrared infrared-stimulated luminescence (MET-pIRIR) dating method was utilized to obtain the absolute ages from the Dongheishan (DHS) section in CSM region. Preheat plateau and dose recovery tests indicate that the MET-pIRIR signals of 250 °C and 300 °C have negligible anomalous fading and they can give reliable ages for the loess since ∼270 ka. Luminescence dating results suggest that the DHS loess mainly accumulated from 265 ± 12 ka to 93 ± 4 ka. The loess sedimentation rates during ∼195 ± 18–108 ± 4 ka were much lower than expected in the DHS section, which occurred approximately correlates with the Qingshui erosion period (∼136 ka), as indicated by the planation surface outside the CSM. Both the grain-size characteristics and sedimentation rate variations suggest that the dust sources of the DHS loess were primarily proximal sediments, which is possibly due to frequent variations in dust provenances caused by plentiful precipitation during the interglacial periods and diversions of the Yellow River. This study implies that the CSM loess with a good chronology could be utilized to decipher regional sedimentation and climatic changes processes.

The Caspian region provides the basis of the stratigraphy and palaeogeography of the Pleistocene of Central Eurasia, and has been actively studied for more than 200 years. Many issues concerning the palaeogeographic history of the various basins of Caspian Quaternary remain unsolved, but the main problem centres on uncertainties in the chronology. Previous chronological studies have focused on a detailed description of the sedimentation history in the Lower Volga and Eastern Caucasus, ignoring a number of unique sites on the eastern Caspian coast, mainly due to inaccessibility. We obtained access to one of the most complete sections, western Cheleken, located on the Caspian coast of Turkmenistan. Within this sandy and generally lowland coast, the western part of the Cheleken peninsula forms a 10 km wide cliff opening a unique series of Middle Pleistocene - Holocene sediments which record in detail the history of Caspian transgressions and regressions. Stratigraphical, geomorphological and palaeontological studies of the section were supplemented with luminescence and radiocarbon dating. Analysis of Caspian molluscs and luminescence ages allowed the reconstruction of the sedimentary history of this region during one of the most important events of the Caspian Basin: the Early and Late Khazarian, Khvalynian and Novocaspian transgression/regression series. Luminescence dating of quartz and feldspar provided 12 OSL, IR₅₀ and pIRIR₂₉₀ ages, comparison of which showed that quartz grains were sufficiently bleached before deposition. Our chronology provides, for the first time, a deeper understanding of the sedimentation and environmental history in this region and the entire Caspian Sea. The Early Khazarian transgression occurred here at ∼220–200 ka (MIS 7). The Late Khazarian stage recorded in shallow-marine clays had relatively stable level ∼150–130 ka ago. In the second half of MIS 5 sea-level decreased and sedimentation was controlled by a large river, most probably the palaeo-Amu-Daria. The Early Khvalynian stage started at ∼27 ka and continued presumably until ∼14 ka.

Wind is a significant geomorphological agent in formerly glaciated areas and aeolian deposits surround and stretch across the Store Mosse (Great Bog) bog complex in southwestern Sweden. Both peat and aeolian sand are underlain by lacustrine sediment and the deposits record the area's transition from an initially ice-dammed lake to Ancient Lake Bolmen, which gradually drained, exposing sediments to wind erosion and allowing peat to start forming in basins.

Here, we present 25 luminescence ages from lacustrine, fluvial and aeolian deposits that range from the time of deglaciation (∼14.5 ka) to the late Holocene (∼3 ka). Most of the waterlain sediments are dated to 11.5–11 ka while the bulk of the dunes formed 10–6.5 ka ago, possibly during two phases in the early and early-middle Holocene, respectively. The parabolic shape of some dunes indicates aeolian deposition or reworking in a partially vegetated environment, and contemporary dune and peat formation suggest a mosaic landscape in the early Holocene. Younger sand drift events and re-activation of some dunes are corroborated by windblown dust events in mid-late Holocene and are likely related to regional storm periods. The results add to the growing understanding of aeolian activity in formerly glaciated landscapes and illustrate a complex interaction of lacustrine, fluvial and aeolian processes.

The optically stimulated luminescence (OSL) dating was done on 180–250 μm quartz grains, which showed relatively dim luminescence signals dominated by a fast component. Several ages have relatively low precision which could be due to sediment mixing, either by bioturbation or by sampling across a significant layer thickness with an auger.

The coupled ESR and U-series (ESR/U-series) method has been increasingly utilized for dating fossil teeth from Early to Middle Pleistocene hominid sites. One significant advantage of this method is its ability to directly analyze fossil animal or human teeth. However, compared with other radiometric methods such as ¹⁴C charcoal dating, U-series carbonate dating, and OSL sediment dating, this dating method is rarely employed for Late Pleistocene or younger sites. In this study, we present an ESR/U-series dating investigation conducted at the Naminan site, a Paleolithic-Neolithic transition (P–N transition) site situated on the Sino-Myanmar border. The ESR/U-series analysis of eleven dental samples yields an age range of 18.1–13.2 ka for the fossils. These obtained ages are generally consistent with the ¹⁴C chronology of the site. When dealing with young fossil samples, it was observed that due to relatively low uranium concentration in dental tissues, internal dose rate plays a less significant role compared to external beta and gamma dose rates in the total dose rate of the fossil samples. Consequently, evaluating the dose rate of surrounding sediment becomes a primary source of uncertainty. Additionally, in this study we attempted to employ the standardized growth curve (SGC) and representative dose response curve method for determining Equivalent Dose (D_E), which was then compared with values obtained using additive dose method (ADM). Although the precision of D_E estimated by two methods are comparatively lower than that of ADM, it demonstrates the potential to efficiently determine a more rational D_max for irradiation, identify samples with stratigraphic disturbances, and analyze small or valuable fossil specimens.

The environment of the Tibetan Plateau (TP) is extremely sensitive to global climate change, and the frequent aeolian activity on the central TP generates large amounts of dust with the result that the region has a major impact on regional and global environmental change. The extensive aeolian dunes on the central TP provide a direct and valuable archive of aeolian activity; however, the age and sediment deposition processes of these dunes are still poorly understood. Optically stimulated luminescence (OSL) dating, an effective method for dating aeolian sediments, has been used sparingly in the region. In this study, we applied quartz single-aliquot regenerative-dose (SAR) OSL, K-feldspar post-infrared infrared-stimulated luminescence (pIRIR), and single-grain K-feldspar pIRIR methods to determine the ages of two well-preserved sand dunes in the Lunpola (LD) and Tuotuohe (TTH) river basins in the central TP. Our results showed that the quartz OSL signal of the TTH dune was dim, while the LD dune quartz exhibited a higher OSL sensitivity than that of the TTH dune. The high recuperation observed could be attributed to the low signal-to-noise ratio of the OSL signals. The K-feldspar signal was bright and the pIR₅₀IR₁₇₀ signal could be used to date young dune samples in the central TP, whereas it could be affected by the residual dose, or incomplete bleaching in the TTH profile, resulting in age overestimation. The single-grain K-feldspar protocol had a good potential for dating the young TP dunes. Multi-method luminescence dating is recommended for the cross-checking of young dune samples with low OSL sensitivity in the TP. Our luminescence dating reveals that aeolian dunes in the central TP formed approximately 385 to 330 a and persisted to the present, possibly in response to climate change since the late stage of Little Ice Age (1400−1850 CE).