Köpping, J, Magee, C orcid.org/0000-0001-9836-2365, Cruden, AR et al. (2 more authors) (Cover date: 1 February 2022) The building blocks of igneous sheet intrusions: insights from 3D seismic reflection data. Geosphere, 18 (1). pp. 156-182. ISSN 1553-040X
Abstract
The propagating margins of igneous sills (and other sheet intrusions) may divide into laterally and/or vertically separated sections, which later inflate and coalesce. These components elongate parallel to and thus record the magma flow direction, and they can form either due to fracture segmentation (i.e., “segments”) or brittle and/or non-brittle deformation of the host rock (i.e., “magma fingers”). Seismic reflection data can image entire sills or sill-complexes in 3-D, and their resolution is often sufficient to allow us to identify these distinct elongate components and thereby map magma flow patterns over entire intrusion networks. However, seismic resolution is limited, so we typically cannot discern the centimeter- to meter-scale host rock deformation structures that would allow the origin of these components to be interpreted. Here, we introduce a new term that defines the components (i.e., “elements”) of sheet-like igneous intrusions without linking their description to emplacement mechanisms. Using 3-D seismic reflection data from offshore NW Australia, we quantify the 3-D geometry of these elements and their connectors within two sills and discuss how their shape may relate to emplacement processes. Based on seismic attribute analyses and our measurements of their 3-D geometry, we conclude that the mapped elements likely formed through non-elastic-brittle and/or non-brittle deformation ahead of the advancing sill tip, which implies they are magma fingers. We show that thickness varies across sills, and across distinct elements, which we infer to represent flow localization and subsequent thickening of restricted areas. The quantification of element geometries is useful for comparisons between different subsurface and field-based data sets that span a range of host rock types and tectonic settings. This, in turn, facilitates the testing of magma emplacement mechanisms and predictions from numerical and physical analogue experiments.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Authors. This paper is published under the terms of the CC-BY-NC license. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 Nov 2021 10:08 |
Last Modified: | 11 Aug 2023 14:01 |
Published Version: | https://pubs.geoscienceworld.org/gsa/geosphere/art... |
Status: | Published |
Publisher: | Geological Society of America |
Identification Number: | 10.1130/GES02390.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:180306 |
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