DOI: 10.1016/j.quascirev.2015.02.015
Scopus记录号: 2-s2.0-84925624392
论文题名: U, Th and Pa insights into sedimentological and paleoceanographic changes off Hudson Strait (Labrador Sea) during the last ~37ka with special attention to methodological issues
作者: Nuttin L. ; Maccali J. ; Hillaire-Marcel C.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 115 起始页码: 39
结束页码: 49
语种: 英语
英文关键词: 231Pa and 230Th excess calculation
; Heinrich events
; Hudson Strait
; Labrador Sea
; Late Quaternary
; Laurentide Ice Sheet
; Paleoceanography
; Sedimentary processes
; U- and Th-series isotopes
Scopus关键词: Glaciers
; Isotopes
; Organic carbon
; Sedimentology
; Sediments
; Heinrich Events
; Hudson Strait
; Labrador Sea
; Late quaternary
; Laurentide ice sheets
; Paleoceanography
; Sedimentary process
; Uncertainty analysis
; authigenesis
; carbonate
; continental slope
; core analysis
; diagenesis
; Heinrich event
; ice sheet
; isotopic composition
; organic carbon
; paleoceanography
; protactinium
; sediment chemistry
; sedimentology
; shelf break
; thorium
; uranium
; water column
; Atlantic Ocean
; Canada
; Hudson Strait
; Labrador Sea
; Laurentian Mountains
; Quebec [Canada]
英文摘要: A ~9m-long sediment core spanning the last ~37ka has been raised from the lower Labrador continental slope, off the Hudson Strait shelf edge. It has been analyzed for its U, Th and Pa isotope contents, along with current sedimentological parameters, as a means to retrieve information about sedimentological changes in response to northeastern Laurentide Ice Sheet (LIS) margin instabilities. The sequence yielded a high-resolution record of subglacial detrital carbonate pulses from Hudson Strait assigned to "Heinrich events" H2 and H1, whereas H0 was missing. Large variations in bulk sediment U- and Th-contents as well as in 234U/238U activity ratio are observed throughout the sequence, leading to large uncertainties when calculating excesses in 231Pa and 230Th (231Paxs and 230Thxs ) over their supported and in-growth fractions (i.e., inherited from detrital minerals and produced from authigenic and diagenetic U-uptake). In particular, 234U excesses or deficits vs238U (-115‰<δ234U<+126‰) are observed throughout the sequence, suggesting occasional U-uptake from the water column and/or some late diagenetic mobility along discrete redox gradients, despite the overall low and little variable organic carbon content (0.3±0.1%) observed. The above uncertainties in 231Paxs and 230Thxs estimates and the large variability in geochemical and sedimentary fluxes off the northeastern LIS margin, lead us to downgrade the potential paleoceanographic information yielded by these isotopes in such a setting. Nonetheless, the H2 and H1 layers are highlighted by very low initial excesses in both 230Thxs and 231Paxs , indicating their extremely fast deposition. Throughout most of the sedimentary sequence, the calculated initial 230Thxs fluxes are nearly in balance with 230Th production in the overlying water column. Exceptions are the H2 layer, an interval succeeding H1, and the post-glacial sediment. The estimated initial (231Paxs /230Thxs ) ratios are generally lower than their production rate in the water column (i.e., 0.092), indicating nearly continuous preferential export of 231Paxs over the last ~37cal ka BP, thus the persistence of some deep currents throughout the interval. © 2015 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59957
Appears in Collections: 过去全球变化的重建
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作者单位: GEOTOP-UQAM, C.P. 8888, Succ. Centre-Ville, Montréal, QC, Canada
Recommended Citation:
Nuttin L.,Maccali J.,Hillaire-Marcel C.. U, Th and Pa insights into sedimentological and paleoceanographic changes off Hudson Strait (Labrador Sea) during the last ~37ka with special attention to methodological issues[J]. Quaternary Science Reviews,2015-01-01,115