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Title: Fingerprinting ice-rafted detritus ice stream sources in the northeast Atlantic during the Last Glacial Stage
Author: Purcell, Catriona
ISNI:       0000 0004 7432 2301
Awarding Body: Bangor University
Current Institution: Bangor University
Date of Award: 2018
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Ice-rafted detritus (IRD) across the North Atlantic provides an important archive for reconstructing the dynamics of adjacent ice margins during the Last Glacial Maximum (LGM). The complex relationship between ice sheet mass balance and IRD flux is still unclear; an increase in IRD could indicate both a positive or a negative mass balance. To address these uncertainties, the source of the IRD needs to be established. Determining the source of IRD for the British Irish Ice Sheet (BIIS) hitherto has only identified broad lithospheric provenances. This study aimed to link IRD within three adjacent deep ocean cores to individual ice streams draining the former BIIS using Xray Fluorescence (XRF) core scanning to define elemental geochemical provinces. Principal Component Analysis was used to establish five glacigenic ice stream end members from the former BIIS: 1) Irish Sea; 2) Celtic Sea; 3) Donegal; 4) Malin Sea and 5) Minch. These end members were then used to geochemically link the IRD in the deep ocean to ice stream source. All three deep ocean cores record BIIS IRD flux; contribution of IRD from the ice streams is governed by the presence of a marineterminating margin and the direction of the surface currents which are shown to be variable during deglaciation. Significant BIIS IRD contribution to the deep ocean occurs between 31-20 kyr BP. Analyses suggests a marine-terminating BIIS pre-Heinrich event 4 and provides offshore evidence for a smaller regionalised marine terminating margin ~14 kyr BP and during the Younger Dryas stadial. The data highlight shifts in the timing of ice stream vs. ice lobe contribution from adjacent sources (Hebrides Ice Stream vs. Donegal Bay ice lobe) and that IRD source in the Rosemary Bank has stronger affinities with the Hebrides Ice Stream than with the adjacent Minch Ice Stream, indicating northward iceberg drift along the NW sector of the margin during and following the Last Glacial Maximum.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available