Stanislaus G. Fabian, Stephen J. Gallagher, David De Vleeschouwer
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引用次数: 0
Abstract
Deep Sea Drilling Program (DSDP) Site 548 was cored in 1984 at a water depth of 1256 m on the Goban Spur, offshore southwest Ireland. Coring retrieved a ~100-m-thick Pleistocene contourite sequence. This study uses planktonic foraminiferal assemblage and benthic foraminiferal oxygen isotope analyses to establish an age model for the upper 40 m of this core. This site's multidisciplinary analyses of planktonic foraminiferal assemblages, lithic grains, facies and calcium carbonate concentration reveal a 250 000-year record of the North Atlantic polar front variability and British–Irish Ice Sheet (BIIS) history. The sequence is characterized by alternations of ice rafted debris (IRD) laden pelagic mud facies with calcium carbonate-rich silty sand contourite facies that track glacial/interglacial cycles. The polar front migrated southward across the area several times during glacial maxima and stadial periods, while warmer Mediterranean Outflow Water (MOW) flowed northward across the region during interglacial and interstadial periods depositing contourites. Lithic analyses reveal a complex history of IRD deposition associated with iceberg calving from the Laurentide Ice Sheet and northwest European ice sheets, mainly the BIIS. Comparison between the Goban Spur (DSDP Site 548) and the Celtic Margin (MD03-2692) and central North Atlantic Integrated Ocean Drilling Program (IODP) Site U1308 suggests differences between the ‘non-Laurentide Ice Sheet’ Heinrich Events (HE) 6 and 3 at the Goban Spur, with IRD from the BIIS being prominent during HE 6 and IRD from other European ice sheets north of the BIIS likely being more dominant during HE 3. The nature of lithics in IRD-rich horizons during Terminations 3, 3A, 2 and 1 suggests significant iceberg calving episodes preceding BIIS retreat during the onset of interstadial intervals.
期刊介绍:
Boreas has been published since 1972. Articles of wide international interest from all branches of Quaternary research are published. Biological as well as non-biological aspects of the Quaternary environment, in both glaciated and non-glaciated areas, are dealt with: Climate, shore displacement, glacial features, landforms, sediments, organisms and their habitat, and stratigraphical and chronological relationships.
Anticipated international interest, at least within a continent or a considerable part of it, is a main criterion for the acceptance of papers. Besides articles, short items like discussion contributions and book reviews are published.