Cryptotephrochronology in the North Atlantic Region : Linking Greenland Ice and North Atlantic Marine Sediments
Abstract
Tephrochronology is a powerful technique that can be utilised for the correlation and synchronisation of disparate palaeoclimatic records. Thus, this technique has considerable potential for addressing key questions relating to rapid climatic events that characterised the last glacial period. In particular, our search for microscopic tephra layers or cryptotephras within the Greenland ice-cores and marine cores from the North Atlantic Ocean has the potential to test the phase relationships between the atmospheric and oceanic responses to these high-magnitude and abrupt climatic events. Here we report on results of investigations of the MIS 5 to 2 time period drawing on examples from several North Atlantic marine cores from various sites within the North Atlantic including the Rockall Trough, Faroe Islands region, Goban Spur, Gardar Drift and Irminger Basin. These investigations fall within the context of the SMART and TRACE projects. Several cryptotephra horizons have been identified by applying techniques first developed for terrestrial sedimentary material. The two main challenges associated with cryptotephra work in the glacial North Atlantic are i) determining the dominant transportation processes and ii) assessing the influence of secondary reworking processes and the integrity of the isochrons. The potential influence of these processes is investigated by assessing shard size, geochemical (major and trace element) heterogeneity and co-variance of IRD input and sortable silt for some cores. High-resolution investigations of the Greenland ice-cores of NGRIP, GRIP and NEEM over the same time period have identified cryptotephras from numerous previously unrecognised eruptions. The principal source of horizons is Iceland, with some correlated to specific volcanic systems such as Katla, Grimsvötn, Hekla and Veidivötn-Bardabunga. An overarching aspect of this work is the robust geochemical fingerprinting of the small glass shards within these cryptotephras using the characterisation techniques of EPMA and LA-ICP-MS. Recent advances in the spatial resolution of both techniques have been pivotal to providing characterisations for the correlation of cryptotephras between the ice and marine sequences.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.V31F..08A
- Keywords:
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- 0724 CRYOSPHERE / Ice cores;
- 4901 PALEOCEANOGRAPHY / Abrupt/rapid climate change;
- 4994 PALEOCEANOGRAPHY / Instruments and techniques;
- 8455 VOLCANOLOGY / Tephrochronology