Investigation of the North Atlantic Heinrich events using molecular approach
The aim of this thesis is to investigate the application of biomarkers to study the provenance of allochthonous organic matter deposited in the North Atlantic during the last glacial period mainly as ice rafted debris (IRD) in Heinrich Layers (HLs). Two novel approaches are used in this work: The bi...
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| Format: | Thesis |
| Language: | unknown |
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2005
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| Online Access: | http://etheses.dur.ac.uk/2762/ http://etheses.dur.ac.uk/2762/1/2762_839_-_vol_1.PDF http://etheses.dur.ac.uk/2762/2/2762_839-vol2.pdf |
| Summary: | The aim of this thesis is to investigate the application of biomarkers to study the provenance of allochthonous organic matter deposited in the North Atlantic during the last glacial period mainly as ice rafted debris (IRD) in Heinrich Layers (HLs). Two novel approaches are used in this work: The biomarker composition of sedimentary organic matter is used to characterise and compare possible sources and sinks of IRD• Glacigenic debris flows (GDFs) are used as proxies for possible sources of IRD in the deep ocean. The distribution of photosynthetic pigments, n-alkanes, highly branched aliphatic hydrocarbons (unresolved complex mixture (UCM) in the gas chromatogram) and long- chain alkenones in the sediments from the possible sources and sinks of IRD IS analysed. Sources of IRD are represented by GDF deposits from the Nordic Seas and the western Atlantic margins. Sinks are represented by deep-sea cores containing HLs: cores รบ90-09 and ODP 609 are from the main area of IRD deposition, "IRD belt", and cores MD95-2024 and HU87-025֊07P are from Labrador Sea. GDF and HL sediments generally contain a very high proportion of biodegraded and thermally mature organic matter originating from ancient outcrops eroded by former ice streams. Most hemipelagic sediments overlying GDFs or HLs in the deep-sea cores contain signatures of less reworked organic matter. GDF sediments at the North Atlantic margins are largely homogenous in their biomarker composition; they contain biomarker distributions that are characteristic and unique to each GDF deposit and thus significantly different from those of the overlying hemipelagic sediments. It was concluded that the biomarker fingerprints of the organic matter in each GDF can be considered as combined signatures of a variety of organic-rich outcrops eroded by a particular ice stream and therefore can be used to constrain the sources of IRD in the North Atlantic. “Typical" HLs 1, 2, 4 & 5 can be identified in the sedimentary records on the basis of the biomarker composition of ... |
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