Microstructural evidence for crystallization regimes in mafic intrusions: a case study from the Little Minch Sill Complex, Scotland

Nicoli, Gautier and Holness, Marian B. and Neufeld, Jerome A. and Farr, Robert (2018) Microstructural evidence for crystallization regimes in mafic intrusions: a case study from the Little Minch Sill Complex, Scotland. Contributions to Mineralogy and Petrology, 173 (12). ISSN 0010-7999 DOI https://doi.org/10.1007/s00410-018-1525-7

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Official URL: https://doi.org/10.1007/s00410-018-1525-7

Abstract

The magma forming the 20 m thick crinanitic/picrodoleritic Dun Raisburgh sill, part of the Little Minch Sill Complex of NW Scotland, comprised a mafic carrier liquid with a crystal cargo of plagioclase and olivine (1 vol%). The olivine component of the cargo settled on the floor of the intrusion while the more buoyant plagioclase component remained suspended during solidification, resulting in a relatively high plagioclase content in the centre of the sill. The settled olivine grains form a lower fining-upwards sequence overlain by a poorly sorted accumulation formed of grains that grew within the convecting magma. The accumulation of olivine on the sill floor occurred over 5–10 weeks, synchronous with the upwards-propagation of a solidification front comprising a porous (~ 70 vol% interstitial liquid) plagioclase-rich crystal mush.

Item Type: Article
Uncontrolled Keywords: 2018AREP; IA73
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Contributions to Mineralogy and Petrology
Volume: 173
Identification Number: https://doi.org/10.1007/s00410-018-1525-7
Depositing User: Sarah Humbert
Date Deposited: 23 Nov 2018 12:01
Last Modified: 23 Nov 2018 12:01
URI: http://eprints.esc.cam.ac.uk/id/eprint/4361

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