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DOI	10.1016/j.quascirev.2020.106422
	U-Th dating of lake sediments: Lessons from the 700 ka sediment record of Lake Junín; Peru
	Chen C.Y.; McGee D.; Woods A.; Pérez L.; Hatfield R.G.; Edwards R.L.; Cheng H.; Valero-Garcés B.L.; Lehmann S.B.; Stoner J.S.; Schwalb A.; Tal I.; Seltzer G.O.; Tapia P.M.; Abbott M.B.; Rodbell D.T.
发表日期	2020
ISSN	0277-3791
卷号	244
英文摘要	Deep sediment cores from long-lived lake basins are fundamental records of paleoenvironmental history, but the power of these reconstructions has been often limited by poor age control. Uranium-thorium (U-Th) dating has the potential to fill a gap in current geochronological tools available for such sediment archives. We present our systematic approach to U-Th date carbonate-rich sediments from the ∼100m drill core from Lake Junín, Peru. The results form the foundation of an age-depth model spanning ∼700 kyrs. High uranium concentrations (0.3–4 ppm) of these sediments allow us to date smaller amounts of material, giving us the opportunity to improve sample selection by avoiding detrital contamination, the greatest factor limiting the success of previous U-Th dating efforts in other lake basins. Despite this advantage, the dates from 174 analyses on 55 bulk carbonate samples reveal significant scatter that cannot be resolved with traditional isochrons, suggesting that at least some of the sediments have not remained closed systems. To understand the source of noise in the geochronological data, we first apply threshold criteria that screen samples by their U/Th ratio, reproducibility, and δ234Uinitial value. We then compare these results with facies types, trace element concentrations, carbonate and total organic carbon content, color reflectance, mineralogy, and ostracode shell color to investigate the causes of open system behavior. Alongside simulations of the isotopic evolution of our samples, we find that the greatest impediment to U-Th dating of these sediments is not detrital contamination, but rather post-depositional remobilization of uranium. Examining U-Th data in these contexts, we identify samples that have likely experienced the least amount of alteration, and use dates from those samples as constraints for the age-depth model. Our work has several lessons for future attempts to U-Th date lake sediments, namely that geologic context is equally as important as the accuracy and precision of analytical measurements. In addition, we caution that significant geologic scatter may remain undetected if not for labor intensive tests of reproducibility achieved through replication. As a result of this work, the deep sediment core from Lake Junín is the only continuous record in the tropical Andes spanning multiple glacial cycles that is constrained entirely by independent radiometric dates. © 2020 Elsevier Ltd
英文关键词	Age model; Geochronology; ICDP; Lakes lagoons & swamps; Paleoclimatology; Quaternary; Sedimentology; South America; U-Th series
语种	英语
scopus关键词	Binary alloys; Carbonation; Core drilling; Geochronology; Lake pollution; Lakes; Minerals; Organic carbon; Sediments; Thorium compounds; Trace elements; Uranium alloys; Accuracy and precision; Color reflectance; Radiometric dates; Reproducibilities; System behaviors; Total organic carbon content; Trace element concentrations; Uranium concentration; Thorium alloys; biostratigraphy; color; core analysis; facies analysis; geochronology; lacustrine deposit; ostracod; paleoenvironment; remobilization; shell; total organic carbon; trace element; uranium series dating; Junin; Lake Junin; Peru; Ostracoda
来源期刊	Quaternary Science Reviews
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/151348
作者单位	Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography, Cambridge, MA, United States; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States; Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, United States; Institut für Geosysteme und Bioindikation, Technische Universität Braunschweig, Braunschweig, Germany; Department of Geological Sciences, University of Florida, Gainesville, FL, United States; College of Earth, Ocean, and Atmospheric Science, Oregon State University, Corvallis, OR, United States; Department of Earth and Environmental Sciences, University of Minnesota Twin Cities, Minneapolis, MN, United States; Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Pyrenean Institute of Eco...
推荐引用方式 GB/T 7714	Chen C.Y.,McGee D.,Woods A.,et al. U-Th dating of lake sediments: Lessons from the 700 ka sediment record of Lake Junín; Peru[J],2020,244.
APA	Chen C.Y..,McGee D..,Woods A..,Pérez L..,Hatfield R.G..,...&Rodbell D.T..(2020).U-Th dating of lake sediments: Lessons from the 700 ka sediment record of Lake Junín; Peru.Quaternary Science Reviews,244.
MLA	Chen C.Y.,et al."U-Th dating of lake sediments: Lessons from the 700 ka sediment record of Lake Junín; Peru".Quaternary Science Reviews 244(2020).