Tephra constraints on rapid climatic events (TRACE): new results from the Greenland ice-cores between 25 and 45 ka b2k
Abstract
The TRACE project aims to utilise tephrochronology to facilitate the high-precision correlation of palaeoclimatic archives preserving a record of the rapid climate changes that characterised the North Atlantic region during the last glacial period. The synchronisation of the Greenland ice-cores to North Atlantic marine records will allow lead/lag relationships between the atmospheric and oceanic systems over these climatic events to be determined and permit an assessment of potential causal mechanisms. Initial investigations of these sequences have focused on the period between 25-45 ka b2k. In the Greenland ice cores 25 tephra layers have been identified within NEEM ice, including a suite of 7 layers that fall between Greenland Interstadial 8 and 9. The NEEM horizons are mostly basaltic in composition. Within the NGRIP ice 34 tephra layers have been identified between 25 and 45 ka BP, including a suite of 13 layers that fall between Greenland Interstadial 8 and 9. Again, basaltic tephra layers dominate, but two rhyolitic and 1 dacitic horizons have also been detected. In both ice cores the basaltic material is predominantly tholeiitic in composition indicating a source from the rift zones of Iceland, with the Grimsvötn and Kverkfjöll systems the most likely sources. One of the NGRIP rhyolitic layers appears to have a source from outside Iceland. Early comparisons of the ice core layers to North Atlantic marine records highlight four potential common tephra horizons, within GS-3 (29,130 × 456 a b2k), GS-9 (38,300 × 703 a b2k), GS-10 (40,220 × 792 a b2k) and GS-12 (43,680 × 877 a b2k). Other potential correlations throughout the period are being explored. We explore all these potential correlations and compare the climatic changes preserved within these cores as constrained by these tephra horizons. Ongoing work on the ice remaining in this time period will allow an assessment of the volcanic frequency to be considered as well as the relationship between volcanic eruptions preserved in the ice cores and climate.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.V11B..03B
- Keywords:
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- 1145 GEOCHRONOLOGY Tephrochronology;
- 4901 PALEOCEANOGRAPHY Abrupt/rapid climate change;
- 4932 PALEOCEANOGRAPHY Ice cores;
- 1105 GEOCHRONOLOGY Quaternary geochronology