Channell, J. E. T. and Harrison, R. J. and Lascu, I. and McCave, I. N. and Hibbert, F. D. and Austin, W. E. N. (2016) Magnetic record of deglaciation using FORC-PCA, sortable-silt grain size, and magnetic excursion at 26 ka, from the Rockall Trough (NE Atlantic). Geochemistry, Geophysics, Geosystems, 17 (5). pp. 1823-1841. ISSN 1525-2027 DOI https://doi.org/10.1002/2016GC006300
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Channell et al. - 2016 - Magnetic record of deglaciation using FORC-PCA, so.pdf - Published Version Available under License Creative Commons Attribution. Download (4MB) | Preview |
Abstract
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).
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 2016AREP; IA71 |
| Subjects: | 03 - Mineral Sciences |
| Divisions: | 03 - Mineral Sciences 08 - Green Open Access |
| Journal or Publication Title: | Geochemistry, Geophysics, Geosystems |
| Volume: | 17 |
| Page Range: | pp. 1823-1841 |
| Identification Number: | https://doi.org/10.1002/2016GC006300 |
| Depositing User: | Sarah Humbert |
| Date Deposited: | 15 Dec 2016 18:25 |
| Last Modified: | 03 Sep 2019 12:41 |
| URI: | http://eprints.esc.cam.ac.uk/id/eprint/3781 |
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