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| 2. |
- Buylaert, Jan-Pieter, et al.
(author)
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A detailed post-IR IRSL chronology for the last interglacial soil at the Jingbian loess site (northern China)
- 2015
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In: Quaternary Geochronology. - : Elsevier BV. - 1871-1014 .- 1878-0350. ; 30, s. 194-199
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Journal article (peer-reviewed)abstract
- The chronology of dust deposition and climate during the last interglacial is poorly known on the Chinese Loess Plateau. Here, 51 samples were taken from the similar to 5 m S1 palaeosol (MIS5) at the desert marginal Jingbian site to develop what is currently the most detailed S1 chronology on the Plateau using instrumental dating techniques. We use the post-IR IRSL signal from sand-sized grains of K-rich feldspar. Signal resetting in the agricultural layer shows that it is possible to almost completely zero this signal in nature. First IR stimulation plateau measurements show that there is no clear dependence of D-e on first IR stimulation temperature between 50 and 260 degrees C suggesting negligible signal fading. Resultant ages are consistent with a last interglacial age (similar to 130 to similar to 75 ka) and are also consistent within errors with continuous linear sedimentation rates. The average mass accumulation rate for S1 is similar to 150 g m(-2) a(-1), considerably higher than at many other sites but within the overall range of Loess Plateau estimates. The remarkably stable sediment accumulation at the site contrasts with a more complex record of environmental and monsoonal change recorded in grain-size and magnetic susceptibility.
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| 3. |
- Han, Zhiyong, et al.
(author)
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Extreme monsoon aridity episodes recorded in South China during Heinrich Events
- 2015
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In: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 440, s. 467-474
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Journal article (peer-reviewed)abstract
- Geological records of climate change since the last glaciation in South China, a core area of the East Asian monsoon, are key to understanding secular variation in the monsoon system. However, with the exception of the speleothems, records from this area with independent age control are few. We investigated aeolian sand deposition on a sand hill on the shore of Poyang Lake in South China and reconstructed the chronological sequence of aeolian deposition using Optically Stimulated Luminescence (OSL) dating. Without exception, all aeolian sediments were deposited within seven periods that generally match the timing of Heinrich events and other cold periods in Greenland. We argue that aeolian sand accumulation in this region is most likely forced by extreme aridity driven by weakening of the summer monsoon, while the characteristics of this deposition are influenced by winter monsoon intensity. The monsoon shifts revealed here suggest a possible link between North Atlantic cooling and summer monsoon strength in South China, and support the intensities of cooling phases recorded in Greenland ice cores.
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| 5. |
- Jiang, Mengyao, et al.
(author)
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Beach ridges of Dali Lake in Inner Mongolia reveal precipitation variation during the Holocene
- 2020
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In: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 35:5, s. 716-725
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Journal article (peer-reviewed)abstract
- Variability in East Asian summer monsoon precipitation during the Holocene remains of debate. In this study, we use a closed lake with well‐dated lake beach ridges located on the margin of the East Asian summer monsoon, a region highly sensitive to monsoon precipitation changes, to obtain a temporal sequence of water volume in North China. The elevation of each beach ridge calibrated to the modern lake level was surveyed. Optically stimulated luminescence dating of undisturbed sediments of beach ridges was performed. The lake area and water volume corresponding to each beach ridge were calculated using a digital elevation model. This study reveals relatively reduced monsoon precipitation from ~12 to 7 ka interrupted by strengthening of the monsoon circulation to a maximum from ~7 to ~5 ka and followed by greatly reduced monsoon intensity until the present day. These results demonstrate that changes in the East Asian summer monsoon precipitation may not be directly driven by global temperature or atmospheric CO2 content. Rather, we suggest that variation in the the monsoon margin precipitation is probably mainly driven by ice volume and subordinately by the summer solar insolation difference between mid‐latitude land and low‐latitude ocean.
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| 6. |
- Li, Guoqiang, et al.
(author)
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A comprehensive dataset of luminescence chronologies and environmental proxy indices of loess-paleosol deposits across Asia
- 2024
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In: npj Climate and Atmospheric Science. - : Springer Nature. - 2397-3722. ; 7:1
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Journal article (peer-reviewed)abstract
- Loess-paleosol sequences have been used in Asia to study climate and environmental changes during the Quaternary. The scarcity of age control datasets and proxy indices analysis data for Asian loess has limited our understanding of loess depositional processes and the reconstruction of paleoclimatic changes from loess-paleosol records. In this study, we present a dataset that includes 1785 quartz optically stimulated luminescence ages and 1038 K-feldspar post-infrared infrared stimulated luminescence ages from 128 loess-paleosol sequences located in different regions of Asia. We generate 38 high-resolution age-depth models of loess records based on the provided datasets. We provide data on 12,365 grain size records, 14,964 magnetic susceptibility records, 2204 CaCO3 content records, and 3326 color reflection records. This dataset contains the most detailed and accurate chronologies and proxy index data for loess records in Asia yet published. It provides fundamental data for understanding the spatial-temporal variations in loess depositional processes and climatic changes across the continent during the mid-late Quaternary.
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| 7. |
- Lu, Huayu, et al.
(author)
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Chinese loess and the Asian monsoon : What we know and what remains unknown
- 2022
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In: Quaternary International. - : Elsevier. - 1040-6182 .- 1873-4553. ; 620, s. 85-97
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Journal article (peer-reviewed)abstract
- The variability and dynamics of the Asian monsoon (AM, hereafter indicates both of the summer and winter monsoons.) at orbital and millennial timescales has attracted wide interest. Chinese loess deposits, covering an area of-500 x 10(3) km(2) and with a thickness of several tens to more than three hundred meters, is an ideal continental archive to reconstruct AM variations during the Quaternary epoch. Over the past thirty years, since the earliest paper published in an international journal that linked the Asian monsoon and Chinese loess deposits, many studies have been undertaken focusing on this research topic. These results have greatly deepened our understanding of the variations of the AM climate and their driving mechanisms during the past-2.6 Myr. In this paper, we emphasize recent progress on the AM variability and dynamics revealed by Chinese loess records; in particular, we discuss the reliability and precision of the timescale and the monsoon proxy indicators for the loess-paleosol sequences, which are two fundamental aspects for understanding AM behavior. We analyze what we know and discuss what we do not know about the AM. We refine the timescale for the typical loess-paleosol sequence in the central Chinese Loess Plateau (CLP), which can be used as a new timescale to study palaeoclimate and palaeoenvironmental changes in the monsoonal Asia. We conclude that low-latitude insolation changes induced by precession, and global ice volume, temperature at high-latitudes, as well as sea-level changes forced variations of the AM at orbital time scales. High-latitude cooling events and low-latitude hydroclimate process at millennial time scales, such as climate changes associated with Heinrich events and Dansgaard-Oeschger cycles in Northern Atlantic and Greenland, have also modulated AM variability. We suggest that high-latitude forcing of AM variations occurs through ocean and atmospheric circulation linkages, although the roles of atmospheric CO2, ocean and vegetation feedbacks need further investigation. In future study, high-resolution independent dating, novel proxy indices and transient numerical simulations are still basic tools to understand the loess deposition and AM variations that require considerably more work. Issues such as reliable spatial comparison and regional linkages of records (dependent on precise and accurate numerical chronologies), and quantitative reconstruction of the AM variations, should be given priority in the study the past climate change in Asia, and low-latitude hydroclimate process.
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| 9. |
- Peric, Zoran, et al.
(author)
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Quartz OSL dating of late quaternary Chinese and Serbian loess : A cross Eurasian comparison of dust mass accumulation rates
- 2019
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In: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 502:Part A, s. 30-44
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Journal article (peer-reviewed)abstract
- Reconstructing dust Mass Accumulation Rate (MAR) from loess deposits is critical to understanding past atmospheric mineral dust activity and requires accurate independent age models from loess deposits across Europe and Asia. Previous correlations of loess in Europe and China have tended to focus on multi-millennial timescales, with no detailed examination of dust MAR at the two ends of the Eurasian loess belt on shorter, sub-orbital scales. Here we present a detailed quartz optically stimulated luminescence (OSL) chronology from the Serbian Titel Loess Plateau (Veliki Surduk loess core) and the Chinese Loess Plateau (Lingtai section). The luminescence ages pass internal tests and show consistent increases in age with depth, with no obvious major hiatuses. However, as reported before, it seems the quartz OSL technique is only capable of accurate age determination up to accrued doses of ca. 150 Gy (ca. 30–40 ka) due to approaching field saturation of the quartz OSL signal. Two age-depth models were used to reconstruct dust MARs, where one utilises OSL data solely and the other additionally makes assumptions about sedimentation rates. Although short-term fluctuations in MAR are model dependent, general MAR patterns between the two sites are very similar, with peak MAR occurring rather late in the last glacial (ca. 13–25 ka). This suggests that at least broad scale trends in dust activity within the last glacial period may be similar at a continental scale.
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| 10. |
- Stevens, Thomas, 1979-, et al.
(author)
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Ice-volume-forced erosion of the Chinese Loess Plateau global Quaternary stratotype site
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time. The reliability of these records is fundamental to understand past global change. Here we use the most detailed luminescence dating age model yet published to show that the ICS chronology for the Quaternary terrestrial type section at Jingbian, desert marginal Chinese Loess Plateau, is inaccurate. There are large hiatuses and depositional changes expressed across a dynamic gully landform at the site, which demonstrates rapid environmental shifts at the East Asian desert margin. We propose a new independent age model and reconstruct monsoon climate and desert expansion/contraction for the last ~250 ka. Our record demonstrates the dominant influence of ice volume on desert expansion, dust dynamics and sediment preservation, and further shows that East Asian Summer Monsoon (EASM) variation closely matches that of ice volume, but lags insolation by ~5 ka. These observations show that the EASM at the monsoon margin does not respond directly to precessional forcing.
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