Description: Publication date: Available online 16 April 2018 Source: Quaternary Geochronology Author(s): Jiang Wu, Huayu Lu, Shuangwen Yi, Zhiwei Xu, Yao Gu, Chenghong Liang, Mengchun Cui, Xuefeng Sun Sand-loess sequences in the desert-loess transition zone are sensitive terrestrial archives for recording past climatic changes and atmospheric dust activities. However, a high-resolution chronology for relative long-term sand-loess sequences is still rare. In this study, we used quartz SAR OSL and K-feldspar pIRIR (pIRIR 290 ) methods to date a 16.8 m sand-loess sequence at Zhenbeitai in Yulin (North-Central China). The quartz is sensitive, fast component dominated but saturates at ∼150 Gy. The measured K-feldspar pIRIR 290 D e showed no dependency on the first IR stimulation temperature between 50 °C and 260 °C. Dose recovery results were consistent with unity up to ∼800 Gy for a test dose of approximately 30% of the equivalent dose to be measured. The resulting pIRIR 290 ages are consistent with the stratigraphy up to ∼121 ka. Thus, a high-resolution chronology up to the last interglacial could be established for the Zhenbeitai sand-loess section. Derived mass accumulation rates show sedimentation rates of ∼10–80 cm/ka for the upper loess (〈10 ka) and ∼15–30 cm/ka for the loess deposits between 57 and 111 ka. Interbedded sands (∼10–65 cm/ka) suggest active dunes in the Mu Us desert during ∼17–10 ka. We found a depositional hiatus of loess between ∼47 ka and 17 ka. The Zhenbeitai sand-loess sequence provides a sensitive record of regional climatic changes in this semiarid zone since last interglacial period.

Description: Publication date: Available online 30 April 2018 Source: Quaternary Geochronology Author(s): L.A. Gliganic, M.C. Meyer, R. Sohbati, M. Jain, S. Barrett Recent work has shown that the optically stimulated luminescence (OSL) signal can be used to determine the duration of daylight exposure for rock surfaces, complementing the surface exposure dating technique using cosmogenic nuclides. In this study we investigate the feasibility of using the newly developed OSL Surface exposure dating technique (OSL-Surf) to date flake scars at lithic quarry sites. We performed the first quantitative validation of the model describing the OSL-Surf dating technique using a controlled laboratory experiment. Our results show that longer laboratory bleaching durations yield deeper OSL-depth profiles, validating the use of OSL-Surf approach for relative dating of rock surfaces with different exposure ages. The OSL-surf model fitted to the OSL-depth profiles (excluding one outlier) yields accurate estimates of known exposure duration, thus confirming the method's usefulness as an absolute dating tool. Consequently, we used the OSL-Surf technique to determine an exposure duration of 117 ± 37 a for a previously unknown-age flake scar that is related to human exploitation of a lithic quarry site in Tibet. The problem of finding a known-age rock surface for parameter calibration was solved by revisiting the sampling site and collecting the scar remaining after earlier sample collection, which has a precisely known exposure age (1.667 a in this study) and identical lithology and irradiation aspect as the flake scar. The calibration sample yielded a measurable OSL-depth profile that could be used to calibrate the model to estimate the exposure duration of a flake scar associated with human exploitation of the area. Finally, we observe that the μ parameter of the OSL-Surf model varies considerably between the laboratory-bleached and two naturally daylight-bleached datasets, despite having identical lithologies. We thus infer that, in addition to lithological controls, the μ parameter is primarily sensitive to the daylight irradiation geometry and only weakly dependent on spectrum of the incident light; this interpretation implies a narrow effective bleaching wavelength band in quartzite. From the practical viewpoint, our results suggest that geometrical factors deserve a careful consideration both while designing the laboratory bleaching experiments as a surrogate of natural bleaching, as well as while choosing the field calibration samples.

Description: Publication date: Available online 9 May 2018 Source: Quaternary Geochronology Author(s): Hao Long, Sumiko Tsukamoto, Jan-Pieter Buylaert, Andrew Sean Murray, Mayank Jain, Manfred Frechen Signal resetting prior to deposition is an important factor for the accuracy of luminescence dating. In this study, resetting of the quartz optically stimulated luminescence (OSL) signal from samples collected from different depositional environments (alluvial, beach, and aeolian sediments) around the Qinghai Lake basin (northeastern Tibetan Plateau) was examined using its inter-comparison with post-IR infrared stimulated luminescence (IRSL) measured at 290 °C (pIRIR 290 ) from K-feldspar. Dose recovery tests were carried out to test the success of the single aliquot regenerative-dose (SAR) protocol for quartz and feldspar. Additionally, stability tests (first IR temperature plateau and g -values) were performed for the pIRIR 290 . We observe that most of the K-feldspar pIRIR 290 and quartz OSL ages are consistent with each other (within 10%), suggesting that the quartz OSL signal was well-bleached prior to the deposition. The ages of loess samples range between ∼13.1 and ∼1.5 ka, the alluvial sediments between ∼35 ka and ∼14 ka, and beach sediments between 60 and 50 ka, corresponding to early Marine Isotope Stage (MIS) 3. These quartz OSL chronologies suggest a lake highstand during very early MIS 3, a lowstand during late MIS 3 and MIS 2, and widespread loess accumulation through the Holocene in the Qinghai Lake basin.

Description: Publication date: Available online 30 April 2018 Source: Quaternary Geochronology Author(s): Xiaomei Nian, Weiguo Zhang, Fengyue Qiu, Jintang Qin, Zhanghua Wang, Qianli Sun, Jing Chen, Zhongyuan Chen, Niankai Liu The optically stimulated luminescence (OSL) sensitivity and OSL signal components of quartz grains were used to investigate provenance changes of Holocene sediments from the Yangtze River delta. The variation of luminescence sensitivity was observed in multiple grain aliquots and single grains of quartz from different sedimentary units of the Yangtze River delta. Laboratory experiments suggest that repeated dosing/bleaching cycles increase the luminescence sensitivity of quartz from the studied sediments. High variable thermal activation curves were observed even for samples from the same sedimentary unit, implying highly diverse sources for the delta deposits of the Yangtze River. Different sedimentary units show quartz with similar OSL component contributions, and repeated dosing/bleaching cycles and heating treatment are unable to affect the relative contributions of the fast and medium components to the bulk OSL signal. The samples from unit 1 (U1, tidal river, 15–11 ka), unit 2 (U2, estuary, 11–9 ka) and unit 6 (U6, delta plain, ca. 1 ka to the present) show relatively higher luminescence sensitivity in comparison to unit 3 (U3, tidal sand ridge, 9–4 ka), unit 4 (U4, prodelta, 4–2.5 ka) and unit 5 (U5, delta front, 2.5–1 ka), implying changing sediment sources over time. Such a temporal variation of sediment source can be explained by the transgressive/regressive history of the Yangtze River delta as well as by Asian monsoon variability since the last deglaciation. It demonstrates that luminescence sensitivity of quartz has great potential for tracing sediment sources in the Yangtze River delta, but more work is needed to characterize specific sources to establish a source-to-sink linkage.

Description: Publication date: Available online 15 May 2018 Source: Quaternary Geochronology Author(s): J.-H. May, S.K. Marx, W. Reynolds, L. Clark-Balzan, G.E. Jacobsen, F. Preusser Swamps in the seasonal tropics have good potential for the reconstruction of late Quaternary monsoonal dynamics. Their successful use, however, has often been compromised by chronological limitations introduced by a variety of depositional and post-depositional processes actively modifying the swamp deposits. We here present and discuss the results of a multiple dating approach at Table Top Swamp (TTS) in northern Australia (the ‘Top End’). Single-grain luminescence dating of quartz was successfully used to provide chronology in the lowermost core where insufficient organic material prevents the application of radiocarbon dating. In the uppermost, fine-grained and peaty section of the core, two different organic fractions (pollen concentrate and humins) were dated with AMS radiocarbon yielding significantly different chronologies. While this could point to the incorporation of younger pollen into the profile along seasonal dry cracks, older humins may also move up in the profile due to vertical mixing. Additional, spatially highly resolved measurements of the bulk OSL signal (Ln and Ln/Tn) combined with data on down-core variation in K, Th, and U concentration, grain size and moisture content were used to (i) guide the development of an age-depth relationship (i.e. age model) for the entire core based on three different data input scenarios, and (ii) test the applicability of novel luminescence screening techniques in seasonal swamp settings. Results suggest only minor differences among the applied models and scenarios, providing an overall reliable representation of the depositional history in the swamp. Even though all resulting age-depth models have relatively large uncertainties in the lower part of the core, there are significant changes in sedimentation rate over time, providing a chronological basis for a more detailed palaeoenvironmental analysis at TTS. The approach used may also be useful in developing age models in other complex environments, and has shown the importance of understanding carbon pathways as well as controls on luminescence signals when developing age models.

Description: Publication date: Available online 10 May 2018 Source: Quaternary Geochronology Author(s): Andrew S. Carr, Alex S. Hay, Mark Powell, Ian Livingstone The Mojave Desert presents an array of Pleistocene lacustrine deposits and aeolian landforms to which, at times, it has proved challenging to apply luminescence methods. We tested the suitability of K-feldspar post-IR IRSL methods using two sites with independent radiocarbon dating – shorelines at Harper Lake and Silver Lake – considering: 1) overall performance of the post-IR IRSL 225 °C (pIRIR 225 ) protocol, 2) effect of test dose size on pIRIR 225 D e , 3) anomalous fading correction of pIRIR 225 ages; 4) preliminary single grain pIRIR 225 results. We observe consistently good performance of the single aliquot pIRIR 225 protocol, with good dose recovery, acceptable recycling ratios, low recuperation and low inter-aliquot scatter. The pIRIR 225 ages for Silver Lake (8.8 ± 0.4 and 11.3 ± 0.5 ka) and Harper Lake (both 25.4 ± 1.4 ka) are in substantially better agreement with the independent dating than low temperature (50 °C) IRSL and quartz OSL ages. pIRIR 225 fading rates are reduced to ∼2.0–2.5% per decade, but there remains a tendency for under-estimation when using uncorrected ages. A need for fading correction is further implied at Harper Lake via comparison with multi-elevated temperature (MET)-PIR age plateaus and pIRIR 290 measurements, although at the younger Silver lake site these methods produce ages nearly identical to the uncorrected pIRIR 225 ages. Preliminary single grain pIRIR 225 measurements suggest a ∼25–30% usable grain yield. At Silver Lake the single grain and single aliquot ages agree well despite over-dispersion of the single grain equivalent dose distribution. At Harper Lake the single grain and single aliquot pIRIR 225 ages also agree well, although a population of insensitive, lower D e grains is observed. These grains are not associated with significantly higher fading rates.

Description: Publication date: Available online 14 May 2018 Source: Quaternary Geochronology Author(s): Robin Blomdin, Arjen P. Stroeven, Jonathan M. Harbor, Natacha Gribenski, Marc W. Caffee, Jakob Heyman, Irina Rogozhina, Mikhail N. Ivanov, Dmitry A. Petrakov, Michael Walther, Alexei N. Rudoy, Wei Zhang, Alexander Orkhonselenge, Clas Hättestrand, Nathaniel A. Lifton, Krister N. Jansson Spanning the northern sector of High Asia, the Altai region contains a rich landform record of glaciation. We report the extent, chronologies, and dynamics of two paleoglaciers on opposite flanks of the Ikh Turgen mountains (In Russian: Chikhacheva Range), straddling the border between Russia and Mongolia, using a combination of remote sensing-based glacial geomorphological mapping, 10 Be surface exposure dating, and geomorphometric analysis. On the eastern side (Mongolia), the Turgen-Asgat paleoglacier, with its potential for developing a large accumulation area (∼257 km 2 ), expanded 40 km down valley, and mean ages from a latero-frontal moraine indicate deglaciation during marine oxygen isotope stage (MIS) 3 (45.1 ± 1.8 ka, n = 4) and MIS 2 (22.8 ± 3.3 ka, n = 5). These minimum age constraints are consistent with other 10 Be glacial chronologies and paleoclimate records from the region, which indicates glacier culmination during cold and wet conditions coinciding with MIS 3 (piedmont-style glaciation; inferred for a few sites across the region) and glacier culmination during cold and dry conditions coinciding with MIS 2 (mainly valley-style glaciation; inferred from several sites across the region). On the western side (Russia), the Boguty paleoglacier had a smaller accumulation area (∼222 km 2 ), and advanced 30 km down valley across a low gradient forefield. Surface exposure ages from two moraine complexes on this side of the mountains exhibit wide scatter (∼14–53 ka, n = 8), making paleoclimate inferences and comparison to other proxies difficult. Ice surface profile reconstructions imply that the two paleoglaciers likely shared an ice divide.

Description: Publication date: Available online 18 May 2018 Source: Quaternary Geochronology Author(s): Jesús Alcalá-Reygosa, David Palacios, Irene Schimmelpfennig, Lorenzo Vázquez-Selem, Leopoldo García-Sancho, Osvaldo Franco-Ramos, José Villanueva, José Juan Zamorano The knowledge of the eruptive history of volcanic centers allows for improving the evaluation of the related risks and hazards in populated areas, but substantially depends on the ability of dating the lava flows. However, traditional methods such as U-Th/He, 40 Ar- 39 Ar, 40 K- 40 Ar and radiocarbon dating are not always suitable. Therefore, an alternative approach based on the combination of in situ -produced 36 Cl based cosmic ray exposure dating, lichenometry and dendrochronology was tested on two lava flows (called Lava flow “A” and “B”) from Pico de Orizaba (Mexico), previously attributed to 16th and 17th century eruptions, respectively. The presented results show that both lava flows are significantly older than their assumed 16th and 17th century ages. Regarding lava flow “A”, the measured in situ -produced 36 Cl concentrations lead to a mean age of 3.03 ± 0.70 ka, while dendrochronology and lichenometry yield minimum ages of 834 and 1130 years, respectively. Regarding lava flow “B”, the measured in situ -produced 36 Cl concentrations lead to a mean age of 1.45 ± 0.35 ka, whereas lichenometry gives a minimum age of ∼1000 years. Overall, this demonstrates that the combination of in situ -produced 36 Cl based cosmic ray exposure dating, lichenometry and dendrochronology has a considerable potential for dating purposes on young deposits and landforms, in particular on lava flows at high elevation sites.

Description: Publication date: Available online 10 May 2018 Source: Quaternary Geochronology Author(s): Zhong He, Hao Long, Linhai Yang, Jie Zhou Palaeoflood reconstruction is of great importance to extend the flooding records and improve the understanding of their relationships with climatic change and geomorphologic evolution. As a large active rift basin in central China, Weihe Basin subsided and infilled in response to the uplift of the Tibetan Plateau and Asian monsoon variations. Many rivers drain out the erodible Chinese Loess Plateau with tremendous detritus and then build up considerable fluvial sequences. Scarcity of organic material and potential poor bleaching make the fluvial deposits difficult to date with radiocarbon and optically stimulated luminescence (OSL) technique, and as a result hinder the palaeoflood reconstruction. This study attempts to compare OSL ages resulted from different grain size fractions of quartz, and then cross-checks with independent radiocarbon ages, aiming to choose proper method to reconstruct the chronology of a fluvial sequence from the valley bank of Shichuan River, a tributary of Weihe River. The results show that the coarse quartz grains experienced better bleaching than fine quartz grains, and the comparison with AMS 14 C ages further confirms the efficient bleaching of the coarse quartz grains before burial. The sufficient bleaching of the coarse fraction could be attributed to sediment source from the upstream mountainous areas and long-distance transportation. Finally, five palaeoflood events were identified at the times of approximately 2.3–2.6 ka, 3.7–3.9 ka, 4.1–4.7 ka, 6.2–6.8 ka, and 8.9–9.2 ka, corresponding to the periods with intensified rainstorm and vegetation degradation associated with climatic deterioration. This study provides a regional evidence to improve our understanding of the response of river system evolution to climate change.

Description: Publication date: Available online 9 May 2018 Source: Quaternary Geochronology Author(s): Aditi Krishna Dave, Marie-Agnes Courty, Kathryn E. Fitzsimmons, Ashok Kumar Singhvi The role of major northwestern Indian rivers in sustaining the Harappan civilisation has been a much-debated topic in Indian archaeology. Reconstruction of palaeo-river courses using remote sensing images and their association with the mighty rivers (viz. Sarasvati and Drishadvati) mentioned in ancient Indian literature, has long been contested. The relationship of these rivers to the Ghaggar and Chautang channels, believed to be the former course of the glacially fed Sutlej and Yamuna rivers respectively, has also been debated. A mighty river of glacial origin has been hypothesised to have sustained the Harappan civilisation, and yet the spatial and temporal associations between palaeo-river courses and the Harappans are poorly understood. We provide new quartz optically stimulated luminescence dates from stratigraphically controlled samples from the palaeo-river bed and adjacent floodplain of the Chautang River near Hissar in Haryana, to elucidate the timing of glacially derived fluvial activity and examine its synchronicity with the Harappan cultures. Our results disprove the proposed link between ancient settlements and large rivers from the Himalayas and indicate that the major palaeo-fluvial system traversing through this region ceased long before the establishment of the Harappan civilisation. These results are further corroborated through a review of archaeological data to assess the spatial and temporal variation in the abundance of Harappan sites along a perennial and ephemeral riverine corridor. This synthesis of archaeological data also urges caution over the linear association of the number of ancient settlements with the strength of rivers.