Testing the use of OSL from quartz grains for dating debris flows in Miyun,northeast Beijing,China |
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| Institution: | 1. College of Resource Environment and Tourism–Capital Normal University, 100048 Beijing, China;2. Center for Nuclear Technologies, Technical University of Denmark, DTU Risø Campus, Frederiksborgvej 399, 4000 Roskilde, Denmark;3. Nordic Laboratory for Luminescence Dating, Department of Geoscience, University of Aarhus, Risø Campus, Frederiksborgvej 399, 4000 Roskilde, Denmark;4. Institute of Earthquake Science, CEA, 100036 Beijing, China;1. State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;2. Department of Earth Sciences, University of Hong Kong, Hong Kong, China;3. Centre for Archaeological Science, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW 2522, Australia;4. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100049, China;1. Sheffield Luminescence Laboratory, Geography Department, University of Sheffield, Winter St., Sheffield S10 2TN, UK;2. Department of Archaeology, University of Sheffield, Northgate House, West Street, Sheffield S1 4ET, UK;3. Environment Department, University of York, Heslington, York SO10 5DD, UK;1. UCLA Earth, Planetary, and Space Sciences, 595 Charles Young Drive East, Box 951567, 90095 Los Angeles, CA, USA;2. University of Sheffield, Geography, Winter Street, Sheffield, South Yorkshire S10 2TN, UK;1. IRAMAT-CRP2A UMR 5060 CNRS – University of Bordeaux-Montaigne, Pessac, France;2. ArScAn – AnTET UMR 7041 CNRS – University of Paris Ouest – Nanterre, Nanterre, France;3. Laboratoire des Sciences du Climat et de l''Environnement UMR 8212 CNRS-CEA-UVSQ, Gif sur Yvette, France;4. CSIC- Institución Milá y Fontanals (IMF), Departamento de Arqueología y Antropología + grupo AGREST, Barcelona, Spain;5. Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Chile;6. Fundação Museu do Homem Americano (FUMDHAM), São Raimundo Nonato, Brazil;7. Département de Préhistoire du Muséum National d''Histoire Naturelle, UMR7194, Paris, France;8. Archaeology department, Universidade Federal de Pernambuco, Recife/PE, Brazil;1. Geological Research Division, Korea Institute of Geoscience and Mineral Resources, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350, Republic of Korea;2. Division of Geology & Geophysics, Kangwon National University, Chuncheon, Kangwon-do, Republic of Korea |
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| Abstract: | Extreme seasonal summer rain storms are common in the mountains to the north east of Beijing and these often result in mass movement of sediment slurries transported for up to a few km. These debris flows can be deadly and are very destructive to infrastructure and agriculture. This project tests the application of luminescence dating to determining the return frequency of such extreme events. The high sediment concentration and the very short flow duration gives very little opportunity for daylight resetting during transport and only a small fraction of the total mass is likely to be reset before transport begins. Here we examine the quartz single-grain dose distribution from a recent known-age (<25 years) debris flow from a small (～3.9 km2) catchment ～140 km north of Beijing and compare it with those from three samples from a sedimentary sequence containing the evidence of multiple flow events.Multi-grain quartz OSL signals are dominated by the fast component and <1% of the 150–200 μm grains give a detectable test dose (4.5 Gy) response. Single-grain beta dose recovery gave a ratio of 0.97 ± 0.06 (n = 30) with an over-dispersion of 23 ± 8% (CAM). Both the recent known age and the palaeo-distributions are highly dispersed with over-dispersions greater than 50%. The average weighted doses range between ～3 mGy and ～6.5 Gy, indicating that all deposits are no more than a few thousand years. Minimum age modelling give an age estimate for the youngest sample consistent with the known age, and minimum ages for the older palaeo-deposits suggest that there have been at least 3 major debris flows in this small catchment in the last 1000 years. |
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| Keywords: | Debris flow deposits Quartz Single-grain dating SAR |
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