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Widespread tephra dispersal and ignimbrite emplacement from a subglacial volcano (Torfajökull, Iceland)

Moles, Jonathan D., McGarvie, Dave, Stevenson, John A., Sherlock, Sarah C., Abbott, Peter M., Jenner, Frances E. and Halton, Alison M. 2019. Widespread tephra dispersal and ignimbrite emplacement from a subglacial volcano (Torfajökull, Iceland). Geology 47 (6) , pp. 577-580. 10.1130/G46004.1

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Abstract

The tephra dispersal mechanisms of rhyolitic glaciovolcanic eruptions are little known, but can be investigated through the correlation of eruptive products across multiple depositional settings. Using geochemistry and geochronology, we correlate a regionally important Pleistocene tephra horizon—the rhyolitic component of North Atlantic Ash Zone II (II-RHY-1)—and the Thórsmörk Ignimbrite with rhyolitic tuyas at Torfajökull volcano, Iceland. The eruption breached an ice mass >400 m thick, leading to the widespread dispersal of II-RHY-1 across the North Atlantic and the Greenland ice sheet. Locally, pyroclastic density currents traveled across the ice surface, depositing the variably welded Thórsmörk Ignimbrite beyond the ice margin and ~30 km from source. The widely dispersed products of this eruption represent a valuable isochronous tie line between terrestrial, marine, and ice-core paleoenvironmental records. Using the tephra horizon, estimates of ice thickness and extent derived from the eruption deposits can be directly linked to the regional climate archive, which records the eruption at the onset of Greenland Stadial 15.2.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Publisher: Geological Society of America
ISSN: 0091-7613
Date of First Compliant Deposit: 24 April 2019
Date of Acceptance: 31 March 2019
Last Modified: 03 Jun 2019 13:14
URI: http://orca.cf.ac.uk/id/eprint/121909

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