Abstract
The Eastern Mediterranean experienced a complex pattern of late Quaternary climatic and environmental change and is a key region for studying the dispersal of humans out of Africa. Examination of the cause and impact of climatic changes in this region requires the development of long, continuous, well-dated sedimentary sequences. This thesis documents the construction of a robust Bayesian age-depth model for marine core MD81-LC31, using luminescence, radiocarbon and tephrochronology techniques.
This study establishes the first marine crypto-tephrostratigraphy from the Levantine Sea, covering the last ~200,000 years and consists of three visible tephra and eight cryptotephra, the majority (two visible and seven cryptotephras) of which derive from Santorini. The detection of multiple sub-Plinian volcanic products in marine sediments distal to Santorini indicates that these eruptions were more explosive than previously thought. Experimental work to refine trace element measurements on small distal tephra shards is presented. Better results were obtained by rastering the laser across the shard during laser ablation ICP-MS measurements than by spot sampling. This approach appears to have considerable potential.
The LC31 age-depth model is used to examine the validity of constructing chronologies based solely on the identification of sapropels and concludes that missing/ghost sapropels may render such chronologies unreliable, without additional dating support. In addition, a previously unknown MIS 5e eruption from the Kos volcano is identified. This tephra has a very similar major element signature to the Kos Plateaux Tuff (KPT), a widespread marker horizon. The MIS 5e Kos tephra was identified via trace element geochemistry on cryptotephra and luminescence dating of marine sediments, highlighting the importance of both techniques in producing robust chronologies for deep-sea cores. However, in the absence of these techniques it is probable that some previously identified occurrences of the KPT are incorrect, with important implications for the geochronology of Eastern Mediterranean marine cores.
This study establishes the first marine crypto-tephrostratigraphy from the Levantine Sea, covering the last ~200,000 years and consists of three visible tephra and eight cryptotephra, the majority (two visible and seven cryptotephras) of which derive from Santorini. The detection of multiple sub-Plinian volcanic products in marine sediments distal to Santorini indicates that these eruptions were more explosive than previously thought. Experimental work to refine trace element measurements on small distal tephra shards is presented. Better results were obtained by rastering the laser across the shard during laser ablation ICP-MS measurements than by spot sampling. This approach appears to have considerable potential.
The LC31 age-depth model is used to examine the validity of constructing chronologies based solely on the identification of sapropels and concludes that missing/ghost sapropels may render such chronologies unreliable, without additional dating support. In addition, a previously unknown MIS 5e eruption from the Kos volcano is identified. This tephra has a very similar major element signature to the Kos Plateaux Tuff (KPT), a widespread marker horizon. The MIS 5e Kos tephra was identified via trace element geochemistry on cryptotephra and luminescence dating of marine sediments, highlighting the importance of both techniques in producing robust chronologies for deep-sea cores. However, in the absence of these techniques it is probable that some previously identified occurrences of the KPT are incorrect, with important implications for the geochronology of Eastern Mediterranean marine cores.
Original language | English |
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Qualification | Ph.D. |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 1 Mar 2023 |
Publication status | Unpublished - 2023 |
Keywords
- Eastern Mediterranean
- Tephrochronology
- Luminescence dating
- Late Quaternary
- Geochronology
- LA-ICP-MS
- Geochemistry
- Marine sediments
- Aegean Volcanic Arc
- Palaeoclimate