2018 Magee etal JSG IRIS.pdf (1.97 MB)
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Structural signatures of igneous sheet intrusion propagation

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journal contribution
posted on 08.11.2018, 12:16 by Craig Magee, James Muirhead, Nick Schofield, Richard J. Walker, Olivier Galland, Simon Holford, Juan Spacapan, Christopher Jackson, William McCarthy
The geometry and distribution of planar igneous bodies (i.e. sheet intrusions), such as dykes, sills, and inclined sheets, has long been used to determine emplacement mechanics, define melt source locations, and reconstruct palaeostress conditions to shed light on various tectonic and magmatic processes. Since the 1970's we have recognised that sheet intrusions do not necessarily display a continuous, planar geometry, but commonly consist of segments. The morphology of these segments and their connectors is controlled by, and provide insights into, the behaviour of the host rock during emplacement. For example, tensile brittle fracturing leads to the formation of intrusive steps or bridge structures between adjacent segments. In contrast, brittle shear faulting, cataclastic and ductile flow processes, as well as heat-induced viscous flow or fluidization, promotes magma finger development. Textural indicators of magma flow (e.g., rock fabrics) reveal that segments are aligned parallel to the initial sheet propagation direction. Recognising and mapping segment long axes thus allows melt source location hypotheses, derived from sheet distribution and orientation, to be robustly tested. Despite the information that can be obtained from these structural signatures of sheet intrusion propagation, they are largely overlooked by the structural and volcanological communities. To highlight their utility, we briefly review the formation of sheet intrusion segments, discuss how they inform interpretations of magma emplacement, and outline future research directions.

History

Citation

Journal of Structural Geology, 2018. In Press

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/School of Geography, Geology and the Environment

Version

AM (Accepted Manuscript)

Published in

Journal of Structural Geology

Publisher

Elsevier

issn

0191-8141

eissn

1873-1201

Acceptance date

17/07/2018

Copyright date

2018

Available date

21/07/2019

Publisher version

https://www.sciencedirect.com/science/article/pii/S0191814118303821?via=ihub

Notes

The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en

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