DOI: 10.1016/j.quascirev.2014.06.022
Scopus记录号: 2-s2.0-84903762098
论文题名: Peak Last Glacial weathering intensity on the North American continent recorded by the authigenic Hf isotope composition of North Atlantic deep-sea sediments
作者: Gutjahr M. ; Frank M. ; Lippold J. ; Halliday A.N.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2014
卷: 99 起始页码: 97
结束页码: 117
语种: 英语
英文关键词: Authigenic hafnium
; Deglaciation
; Fe-Mn oxyhydroxide
; Feldspar weathering
; Incongruent weathering
; Laurentide Ice Sheet
; LGM
; Lu-rich accessory minerals
; Zircon effect
Scopus关键词: Feldspar
; Geochemistry
; Glacial geology
; Glaciers
; Isotopes
; Lead
; Manganese
; Seawater
; Sediments
; Submarine geology
; Weathering
; Zircon
; Accessory minerals
; Authigenic
; Deglaciations
; Feldspar weathering
; Laurentide ice sheets
; LGM
; Oxyhydroxides
; Hafnium
; accessory mineral
; authigenesis
; chemical weathering
; deep-sea sediment
; deglaciation
; feldspar
; hafnium
; isotopic composition
; Last Glacial
; Last Glacial Maximum
; Laurentide Ice Sheet
; paleoceanography
; seawater
; Atlantic Ocean
; Atlantic Ocean (North)
; North America
英文摘要: We have retrieved radiogenic hafnium (Hf) isotope compositions (e{open}Hf) from authigenic Fe-Mn oxyhydroxides of deep northwest Atlantic sediments deposited over the past 26 ka to investigate the oceanic evidence of changes in dissolved weathering inputs from NE America during the last deglaciation. The extraction of seawater-derived Hf isotopic compositions from Fe-Mn oxyhydroxides is not a standard procedure. Comparisons between the Al/Hf ratios and Hf isotopic compositions of the chemically extracted authigenic phase on the one hand, and those of the corresponding detrital fractions on the other, provide evidence that the composition of past seawater has been reliably obtained for most sampled depths with our leaching procedures. This is endorsed most strongly by data for a sediment core from 4250m water depth at the deeper Blake Ridge, for which consistent replicates were produced throughout. The Hf isotopic composition of the most recent sample in this core also closely matches that of nearby present day central North Atlantic seawater. Comparison with previously published seawater Nd and Pb isotope compositions obtained on the same cores shows that both Hf and Pb were released incongruently during incipient chemical weathering, but responded differently to the deglacial retreat of the Laurentide Ice Sheet. Hafnium was released more congruently during peak glacial conditions of the Last Glacial Maximum (LGM) and changed to typical incongruent interglacial e{open}Hf signatures either during or shortly after the LGM. This indicates that some zircon-derived Hf was released to seawater during the LGM. Conversely, there is no clear evidence for an increase in the influence of weathering of Lu-rich mineral phases during deglaciation, possibly since relatively unradiogenic Hf contributions from feldspar weathering were superimposed. While the authigenic Pb isotope signal in the same marine sediment samples traced peak chemical weathering rates on continental North America during the transition to the Holocene a similar incongruent excursion is notably absent in the Hf isotope record. The early change towards more radiogenic e{open}Hf in relation to the LGM may provide direct evidence for the transition from a cold-based to a warm-based Laurentide Ice Sheet on the Atlantic sector of North America. © 2014 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60199
Appears in Collections: 过去全球变化的重建
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作者单位: Institute for Isotope Geochemistry and Mineral Resources, Department of Earth Sciences, ETH Zürich, 8092 Zürich, Switzerland; GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany; Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany; Department of Earth Sciences, University of Oxford, Parks Road, OX1 3PR Oxford, United Kingdom; Oeschger Centre for Climate Change Research, Institute of Geological Sciences, University of Bern, Switzerland
Recommended Citation:
Gutjahr M.,Frank M.,Lippold J.,et al. Peak Last Glacial weathering intensity on the North American continent recorded by the authigenic Hf isotope composition of North Atlantic deep-sea sediments[J]. Quaternary Science Reviews,2014-01-01,99