Mafic tiers and transient mushes: evidence from Iceland

Maclennan, J. (2019) Mafic tiers and transient mushes: evidence from Iceland. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 377 (2139). p. 20180021. ISSN 1364-503X DOI https://doi.org/10.1098/rsta.2018.0021

[img] Text
rsta.2018.0021.pdf - Published Version
Restricted to Registered users only

Download (1MB) | Request a copy
Official URL: https://doi.org/10.1098/rsta.2018.0021

Abstract

It is well established that magmatism is trans-crustal, with melt storage and processing occurring over a range of depths. Development of this conceptual model was based on observations of the products of magmatism at spreading ridges, including Iceland. Petrological barometry and tracking of the solidification process has been used to show that the Icelandic crust is built by crystallization over a range of depths. The available petrological evidence indicates that most of the active rift zones are not underlain by extensive and pervasive crystal mush. Instead, the microanalytical observations from Iceland are consistent with a model where magmatic processing in the lower crust occurs in sills of decimetric vertical thickness. This stacked sills mode of crustal accretion corresponds to that proposed for the oceanic crust on the basis of ophiolite studies. A key feature of these models is that the country rock for the sills is hot but subsolidus. This condition can be met if the porosity in thin crystal mushes at the margins of the sills is occluded by primitive phases, a contention that is consistent with observations from cumulate nodules in Icelandic basalts. The conditions required for the stabilization of trans-crustal mushes may not be present in magmatic systems at spreading ridges. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.

Item Type: Article
Additional Information: © The Author(s)
Uncontrolled Keywords: 2018AREP; IA74
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume: 377
Page Range: p. 20180021
Identification Number: https://doi.org/10.1098/rsta.2018.0021
Depositing User: Sarah Humbert
Date Deposited: 07 Jan 2019 12:33
Last Modified: 07 Jan 2019 12:33
URI: http://eprints.esc.cam.ac.uk/id/eprint/4377

Actions (login required)

View Item View Item

About cookies