Heinrich Events and the British-Irish Ice Sheet: evidences of palaeoceanographic changes in the Rockall Trough
APPROVED The Porcupine Bank is an offshore plateau connected to the Irish Shelf west of Ireland. Its western flank is affected by several water masses associated with the Atlantic Meridional Overturning Circulation (AMOC) and other water masses such as the Mediterranean Overflow Water or modified An...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | unknown |
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Trinity College Dublin. School of Natural Sciences. Discipline of Geology
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| Online Access: | http://hdl.handle.net/2262/102320 https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:RENKENS |
| Summary: | APPROVED The Porcupine Bank is an offshore plateau connected to the Irish Shelf west of Ireland. Its western flank is affected by several water masses associated with the Atlantic Meridional Overturning Circulation (AMOC) and other water masses such as the Mediterranean Overflow Water or modified Antarctic Bottom Water flowing through the adjacent Rockall Trough. The proximity to the former British-Irish Ice Sheet (BIIS) and outermost reach of the former Laurentide Ice Sheet (LIS) makes the Porcupine Bank slope an ideal site for studying abrupt climatic events associated with changes in the above-mentioned water masses and ice sheets. This thesis aims to investigate the potential presence of BIIS and LIS ice-rafting signals at the Porcupine Bank slope during abrupt climatic events, particular Heinrich Events, and how these are connected to oceanographic changes (e.g. temperatures, salinities) to gain a better understanding of ice rafting triggering mechanisms. The sediments of the lower Porcupine Bank slope comprise of a variety of ice rafted debris (IRD) signals which are strongly connected to the dynamic behaviour of the BIIS over the last 55 000 years. A stratigraphic event analysis, carried out on the basis of high-resolution total IRD counts, grain size analyses, planktonic foraminifera census counts (cluster analysis, principal component analysis and N. pachyderma (sin) index) and non-destructive analyses such as X-ray imaging and multi-sensor core logging (magnetic susceptibilities), allowed a distinction between five preserved Heinrich Events (H1 to H5) and independent ice rafting events of the BIIS. The collected data in this thesis allowed a subdivision of the Heinrich Events on the basis of total IRD signatures, sortable silt data (bottom current strength estimates) as well as planktonic foraminifera derived temperatures (census count transfer functions and Mg/Ca) and salinities (δ18O) into three-phased Heinrich Events (H2, H4 and H5), which are strongly linked to so-called grey bands identified ... |
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