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| Channell, J. E. T.; Harrison, R. J.; Lascu, I.; Mccave, I. N.; Hibbert, F. D.; Austin, W. E. N.. |
| 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... |
| Tipo: Text |
Palavras-chave: Magnetic granulometry; FORC-PCA analysis; Sortable silt; Magnetic excursion; Termination I; Rockall Trough. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00333/44456/44128.pdf |
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| Mccave, I. N.; Hall, I. R.. |
| The basis for, and use of, fine grain size parameters for inference of paleoflow speeds is reviewed here. The basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field, experimental data on suspended sediment transport and deposition, and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed. In the deep sea, sorting events occur under resuspension/deposition events in benthic storms. At flow speeds below 10 - 15 cm s(-1), size in the noncohesive "sortable silt'' ( 10 - 63 mm) range is controlled by selective deposition, whereas above that range, removal of finer material by winnowing also plays a role. The best... |
| Tipo: Text |
Palavras-chave: Sortable silt; Grain size; Paleocurrent; Flow speed; Ocean circulation; Contourite; Sediment drift. |
| Ano: 2006 |
URL: https://archimer.ifremer.fr/doc/00234/34515/33417.pdf |
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| Evans, H. K.; Hall, I. R.; Bianchi, G. G.; Oppo, D. W.. |
| Records from Ocean Drilling Program Sites 1057 and 1059 (2584 m and 2985 m water depth, respectively) have been used to reconstruct the behavior of the Deep Western Boundary Current (DWBC) on the Blake Outer Ridge (BOR) from 130 to 60 kyr B. P. (marine isotope stage (MIS) 5 and the 5/4 transition). Site 1057 lies within Labrador Sea Water (LSW) but close to the present-day boundary with Lower North Atlantic Deep Water (LNADW), while Site 1059 lies within LNADW. High-resolution sortable silt mean ((SS) over bar) grain size and benthic delta C-13 records were obtained, and changes in the DWBC intensity and spatial variability were inferred. Comparisons are made with similar proxy records generated for the Holocene from equivalent depth cores on the BOR.... |
| Tipo: Text |
Palavras-chave: Sortable silt; Deep Western Boundary Current; Marine isotope stage 5. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00238/34930/33251.pdf |
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