气候变化领域集成服务门户(CCPortal): Updated cosmogenic chronologies of Pleistocene mountain glaciation in the western United States and associated paleoclimate inferences

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DOI	10.1016/j.quascirev.2020.106427
	Updated cosmogenic chronologies of Pleistocene mountain glaciation in the western United States and associated paleoclimate inferences
	Laabs B.J.C.; Licciardi J.M.; Leonard E.M.; Munroe J.S.; Marchetti D.W.
发表日期	2020
ISSN	0277-3791
卷号	242
英文摘要	Surface exposure dating with terrestrial cosmogenic nuclides (TCNs) has become the primary method for determining numerical ages of Pleistocene mountain glacial deposits and landforms in the conterminous western United States (U.S.) and in numerous other glaciated settings worldwide. Recent updates to models of TCN production and scaling warrant a reconsideration of published exposure ages of moraines of the last two Pleistocene glaciations and associated paleoclimate inferences. Previously reported TCN exposure ages of moraines are recalculated here using newer production rates and scaling models for nuclides helium-3 (3He), beryllium-10 (10Be), aluminum-26 (26Al), and chlorine-36 (36Cl), in most cases yielding significant differences from originally reported ages. Recalculated TCN exposure ages of moraines of the penultimate glaciation display a high degree of variability for individual landforms, particularly toward the younger end of age distributions, suggesting that exposure history is affected by moraine denudation and that older age modes provide the best estimate of the depositional age of these moraines. Oldest exposure ages of penultimate glaciation moraines are well-aligned among mountain ranges across the western U.S. and yield a mean of 138 ± 13 ka, indicating that mountain glaciation occurred in step with global ice volume maxima during marine oxygen isotope stage 6. On average, terminal moraines of the last glaciation date to 19.5 ± 2.3 ka and correspond to the latter part of the global Last Glacial Maximum (LGM). Down-valley recessional moraines representing prolonged glacial stabilizations or readvances to ≥75% of maximum lengths have a mean exposure age of 17.0 ± 1.8 ka, suggesting that these moraine positions were last occupied during Heinrich Stadial 1. Evidence for multiple glacial culminations during the last glaciation is found in several mountain ranges and likely reflects at least two phases of Late Pleistocene climate: an earlier phase when glaciers attained their maximum length in response to cooling during the LGM, and a later phase when glaciers persisted at or readvanced to near-maximum lengths in response to sustained cold temperatures and/or increased precipitation. © 2020 Elsevier Ltd
英文关键词	Moraines; Mountain glaciation; Paleoclimate; Pleistocene; Surface-exposure dating; Terrestrial cosmogenic nuclides; Western United States
语种	英语
scopus关键词	Geomorphology; Isotopes; Landforms; Numerical methods; Cold temperatures; High degree of variability; Last Glacial Maximum; Marine oxygen isotopes; Surface exposure dating; Terminal moraines; Terrestrial cosmogenic nuclides; Western United States; Glacial geology; chronology; cosmogenic radionuclide; glacial deposit; glaciation; Heinrich event; mountain region; Pleistocene; United States
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/151387
作者单位	North Dakota State University, United States; University of New Hampshire, United States; Colorado College, United States; Middlebury College, United States; Western Colorado University, United States
推荐引用方式 GB/T 7714	Laabs B.J.C.,Licciardi J.M.,Leonard E.M.,et al. Updated cosmogenic chronologies of Pleistocene mountain glaciation in the western United States and associated paleoclimate inferences[J],2020,242.
APA	Laabs B.J.C.,Licciardi J.M.,Leonard E.M.,Munroe J.S.,&Marchetti D.W..(2020).Updated cosmogenic chronologies of Pleistocene mountain glaciation in the western United States and associated paleoclimate inferences.Quaternary Science Reviews,242.
MLA	Laabs B.J.C.,et al."Updated cosmogenic chronologies of Pleistocene mountain glaciation in the western United States and associated paleoclimate inferences".Quaternary Science Reviews 242(2020).