DOI: 10.1016/j.quascirev.2016.01.001
Scopus记录号: 2-s2.0-84954324716
论文题名: 150,000 years of loess accumulation in central Alaska
作者: Jensen B.J.L. ; Evans M.E. ; Froese D.G. ; Kravchinsky V.A.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 135 起始页码: 1
结束页码: 23
语种: 英语
英文关键词: Alaska
; Halfway House
; Loess
; Magnetic susceptibility
; Marine isotope stage 5
; Paleomagnetism
; Paleosols
; Quaternary
; Tephra
Scopus关键词: Electromagnetic field effects
; Geomagnetism
; Glacial geology
; Isotopes
; Magnetic susceptibility
; Magnetism
; Stratigraphy
; Surface roughness
; Alaska
; Loess
; Marine isotope stages
; Paleomagnetism
; Paleosols
; Quaternary
; Tephra
; Sediments
; Ovis aries
英文摘要: The Halfway House site in interior Alaska is arguably the most studied loess deposit in northwestern North America. The site contains a complex paleomagnetic and paleoenvironmental record, but has lacked the robust chronologic control that would allow its full potential to be exploited. Detailed reexamination of stratigraphy, paleomagnetics and tephrostratigraphy reveals a relatively complete marine isotope stage (MIS) 6 to Holocene record constrained by the Old Crow (124 ± 10 ka), VT (106 ± 10 ka), Sheep Creek-Klondike (ca. 80 ka), Dominion Creek (77 ± 8 ka) and Dawson (ca. 30.2 cal ka BP) tephras. We show two well-developed paleosols formed during Marine Isotope Stages (MIS) 5e and 5a, while MIS 5c and 5b are either poorly represented or absent. The new tephrostratigraphy presented here is the most complete one to date for the late Pleistocene and indicates MIS 5 sediments are more common than previously recognized. A magnetic excursion within the sediments is identified as the post-Blake excursion (94.1 ± 7.8 ka), providing independent age control and adding to the increasing body of evidence that Alaskan loess is a detailed recorder of variations of the Earth's magnetic field over time. A high-resolution magnetic susceptibility profile placed into this new chronostratigraphic framework supports the hypothesis that wind-intensity is the main variable controlling fluctuations in susceptibility. Correlation of the susceptibility record to global marine δ18O records is complicated by highly variable accumulation rates. We find the lowest rates of accumulation during peak warm and cold stages, while abrupt increases are associated with periods of transition between marine isotope (sub)stages. Building on previous accumulation models for Alaska, surface roughness is likely a leading variable controlling loess accumulation rates during transitions and peak cold periods, but the negligible accumulation during MIS 5e and 5a suggests that loess production was exceedingly low, negating the role of surface roughness. This interplay of variables leads to optimal conditions for loess accumulation during transitions between isotope stages, and to a somewhat lesser extent, stadials and interstadials. © 2016 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59669
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada; Department of Physics, University of Alberta, Edmonton, AB, Canada; Royal Alberta Museum, Edmonton, AB, Canada
Recommended Citation:
Jensen B.J.L.,Evans M.E.,Froese D.G.,et al. 150,000 years of loess accumulation in central Alaska[J]. Quaternary Science Reviews,2016-01-01,135