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Troll VR, Emeleus CH, Nicoll GR, Mattsson T, Ellam RM, Donaldson CH, Harris C. A large explosive silicic eruption in the British Palaeogene Igneous Province. Sci Rep 2019; 9:494. [PMID: 30679443 PMCID: PMC6345756 DOI: 10.1038/s41598-018-35855-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/09/2018] [Indexed: 11/15/2022] Open
Abstract
Large-volume pyroclastic eruptions are not known from the basalt-dominated British Palaeogene Igneous Province (BPIP), although silicic magmatism is documented from intra-caldera successions in central volcanoes and from small-volume ash-layers in the associated lava fields. Exceptions are the Sgùrr of Eigg (58.7 Ma) and Òigh-sgeir pitchstones in the Inner Hebrides (>30 km apart), which have been conjectured to represent remnants of a single large silicic event. Currently available major element data from these outcrops differ, however, creating a need to test if the two pitchstones are really related. We employ a systematic array of methods ranging from mineralogy to isotope geochemistry and find that samples from the two outcrops display identical mineral textures and compositions, major- and trace elements, and Sr-Nd-Pb-O isotope ratios, supporting that the two outcrops represent a single, formerly extensive, pyroclastic deposit. Available isotope constraints suggest a vent in the Hebridean Terrane and available radiometric ages point to Skye, ~40 km to the North. A reconstructed eruption volume of ≥5km3 DRE is derived, suggesting a VEI 5 event or larger. We therefore argue, contrary to long-held perception, that large-volume silicic volcanism and its associated climatic effects were likely integral to the BPIP during the opening of the North Atlantic.
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Affiliation(s)
- Valentin R Troll
- Department of Earth Sciences, Section for Mineralogy, Petrology, Tectonics (MPT), Uppsala University, Villavägen 16, 752 36, Uppsala, Sweden.
| | - C Henry Emeleus
- Department of Earth Sciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Graeme R Nicoll
- Neftex Insights, Halliburton, 97 Jubilee Avenue, Milton Park, Abingdon, Oxfordshire, OX14 4RW, UK
| | - Tobias Mattsson
- Department of Earth Sciences, Section for Mineralogy, Petrology, Tectonics (MPT), Uppsala University, Villavägen 16, 752 36, Uppsala, Sweden
| | - Robert M Ellam
- Scottish Universities Environmental Research Centre (SUERC), Scottish Enterprise Technology Park, Rankine Avenue, East Kilbride, G75 0QF, UK
| | - Colin H Donaldson
- Department of Geography and Geosciences, University of St Andrews, North Street, St Andrews, KY16 9AL, UK
| | - Chris Harris
- Department of Geological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
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