| Autor: |
Channell, J. E. T., Harrison, R. J., Lascu, I., McCave, I. N., Hibbert, F. D., Austin, W. E. N. |
| Přispěvatelé: |
University of St Andrews. Geography & Sustainable Development, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. St Andrews Sustainability Institute, Harrison, Richard [0000-0003-3469-762X], McCave, Ian Nicholas [0000-0002-4702-5489], Apollo - University of Cambridge Repository |
| Jazyk: |
angličtina |
| Rok vydání: |
2016 |
| Předmět: |
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| Zdroj: |
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2016-05, Vol. 17, N. 5, P. 1823-1841 |
| ISSN: |
1525-2027 |
| Popis: |
Research supported by US NSF grants 0850413 and 1014506, and the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement No. 320750. The UK NERC and BGS funded the recovery of Core MD04-2822. Core MD04-2822 from the Rockall Trough has apparent sedimentation rates of ∼ 1 m/kyr during the last deglaciation (Termination I). Component magnetization directions indicate a magnetic excursion at 16.3 m depth in the core, corresponding to an age of 26.5 ka, implying an excursion duration of ∼350 years. Across Termination I, the mean grain size of sortable silt implies reduced bottom-current velocity in the Younger Dryas and Heinrich Stadial (HS)-1A, and increased velocities during the Bølling-Allerød warm period. Standard bulk magnetic parameters imply fining of magnetic grain size from the mid-Younger Dryas (∼12 ka) until ∼ 8 ka. First-order reversal curves (FORCs) were analyzed using ridge extraction to differentiate single domain (SD) from background (detrital) components. Principal component analysis (FORC-PCA) was then used to discriminate three end members corresponding to SD, pseudo-single domain (PSD) and multidomain (MD) magnetite. The fining of bulk magnetic grain size from 12 to 8 ka is due to reduction in concentration of detrital (PSD+MD) magnetite, superimposed on a relatively uniform concentration of SD magnetite produced by magnetotactic bacteria. The decrease in PSD+MD magnetite concentration from 12 to 8 ka is synchronized with increase in benthic δ13C, and with major (∼70 m) regional sea-level rise, and may therefore be related to detrital sources on the shelf that had reduced influence as sea level rose, and to bottom-water reorganization as Northern Source Water (NSW) replaced Southern Source Water (SSW). Publisher PDF |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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