St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Fault-controlled magma ascent recorded in the central series of the rum layered intrusion, NW Scotland

Thumbnail
View/Open
Troll_2020_JP_Fault_controlled_CC.pdf (15.49Mb)
Date
09/10/2020
Author
Troll, V. R.
Mattsson, T.
Upton, B. G.J.
Emeleus, C. H.
Donaldson, C. H.
Meyer, R.
Weis, F.
Dahrén, B.
Heimdal, T. H.
Keywords
Long Loch Fault
Magma recharge
Rum Igneous Centre
Tectonic conduit opening
GE Environmental Sciences
Geophysics
Geochemistry and Petrology
DAS
Metadata
Show full item record
Altmetrics Handle Statistics
Altmetrics DOI Statistics
Abstract
The Palaeogene layered ultrabasic intrusion of the Isle of Rum forms the hearth of the Rum Igneous Centre in NW-Scotland. The regional Long Loch Fault, which is widely held to represent the feeder system to the layered magma reservoir, dissects the intrusion and is marked by extensive ultrabasic breccias of various types. Here we explore the connection between the layered ultrabasic cumulate rocks and breccias of central Rum that characterize the fault zone (the ‘Central Series’) and evaluate their relationship with the Long Loch Fault system. We show that fault splays in the Central Series define a transtensional graben above the Long Loch Fault into which portions of the layered units subsided and collapsed to form the extensive breccias of central Rum. The destabilization of the cumulate pile was aided by intrusion of Ca-rich ultrabasic magmas along the faults, fractures and existing bedding planes, creating a widespread network of veins and dykelets that provided a further means of disintegration and block detachment. Enrichment in LREE and compositional zoning in intra cumulate interstices suggest that the collapsed cumulates were infiltrated by relatively evolved plagioclase-rich melt, which led to extensive re-crystallization of interstices. Clinopyroxene compositions in Ca-rich gabbro and feldspathic peridotite veins suggest that the intruding magma was also relatively water-rich, and that pyroxene crystallized dominantly below the current level of exposure. We propose that the Long Loch Fault opened and closed repeatedly to furnish the Rum volcano with a pulsing magma conduit. When the conduit was shut, pressure built up in the underlying plumbing system, but was released during renewed fault movements to permit dense and often crystal-rich ultrabasic magmas to ascend rapidly from depth. These spread laterally on arrival in the shallow Rum magma reservoir, supplying repetitive recharges of crystal-rich magma to assemble the rhythmic layering of the Rum layered intrusion.
Citation
Troll , V R , Mattsson , T , Upton , B G J , Emeleus , C H , Donaldson , C H , Meyer , R , Weis , F , Dahrén , B & Heimdal , T H 2020 , ' Fault-controlled magma ascent recorded in the central series of the rum layered intrusion, NW Scotland ' , Journal of Petrology , vol. 61 , no. 10 , egaa093 . https://doi.org/10.1093/petrology/egaa093
Publication
Journal of Petrology
Status
Peer reviewed
DOI
https://doi.org/10.1093/petrology/egaa093
ISSN
0022-3530
Type
Journal article
Rights
Copyright © The Author(s) 2020. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Description
Financial support by the Swedish Science Foundation (Vetenskapsrådet), Uppsala University, and the Clough Fund of the Geological Society of Edinburgh are gratefully acknowledged.
Collections
  • University of St Andrews Research
URL
https://academic.oup.com/petrology/article/61/10/egaa093/5920248#supplementary-data
URI
http://hdl.handle.net/10023/23208

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter