Interconnected sills and inclined sheet intrusions control shallow magma transport in the Ferrar large igneous province, Antarctica

Muirhead, James D.; Airoldi, Giulia; Rowland, J. V.; White, James D. L.

doi:10.1130/b30455.1

Cited by 83 publications

(68 citation statements)

References 93 publications

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“…5B; Thomson and Hutton, 2004;Magee et al, 2014;Schofield et al, 2015). The extensive distribution of sill-sill junctions, which are a proxy for feeder relationships, implies that interconnected sills form efficient magma migration pathways (Cartwright and Hansen, 2006;Muirhead et al, 2012;Magee et al, 2014;Schofield et al, 2015). While sill-sill junctions may form via sill-sill abutment or crosscutting (Hansen et al, 2004;Galerne et al, 2011), as opposed to a feeding relationship, the mapping of flow patterns can help to constrain intrusion connectivity within sill complexes.…”

Section: Constraining Magma Flow Patterns In Outcrop and Seismic Datamentioning

confidence: 99%

“…7A, 7B; Galerne et al, 2008;Leat, 2008;Polteau et al, 2008b;Airoldi et al, 2012;Muirhead et al, 2012Muirhead et al, , 2014Svensen et al, 2012;Scheiber-Enslin et al, 2014). In the Ferrar magmatic province specifically, the role of sills in facilitating extensive lateral magma flow is supported by: (1) observed sill-sill feeding relationships (Muirhead et al, , 2014; (2) decreasing Mg# and MgO contents along the length of the Ferrar magmatic province that are consistent with fractional crystallization during lateral magma flow as far as 4100 km from the Weddell Sea region (Elliot et al, 1999;Elliot and Fleming, 2000;Leat, 2008); and (3) the consistent orientation of bridge and/or broken bridge structure long axes and magnetic lineations within sills and interconnected sheets across Antarctica (e.g., in the Theron Mountains, Antarctica) (Dragoni et al, 1997;Hutton, 2009;Airoldi et al, 2012).…”

Section: Karoo-ferrar Lipmentioning

confidence: 99%

“…1A; e.g., Curtis, 1968;Cartwright and Hansen, 2006;Gudmundsson, 2006;Aoki et al, 2013;Aizawa et al, 2014;Muirhead et al, 2014;Tibaldi, 2015) or giant radiating dike swarms, which can facilitate lateral magma flow over hundreds to thousands of kilometers (e.g., Ernst and Baragar, 1992;Ernst et al, 1995;Macdonald et al, 2010). Recent field-, seismic reflection-, and modeling-based research further indicate that plumbing systems at shallow levels (typically <3 km depth), particularly those hosted in sedimentary basins, may instead be characterized by extensive sill complexes (e.g., Chevallier and Woodford, 1999;Smallwood and Maresh, 2002;Thomson and Hutton, 2004;Planke et al, 2005;Cartwright and Hansen, 2006;Kavanagh et al, 2006Kavanagh et al, , 2015Lee et al, 2006;Leuthold et al, 2012;Leat, 2008;Menand, 2008;Polteau et al, 2008a;Cukur et al, 2010;Bunger and Cruden, 2011;Gudmundsson and Løtveit, 2012;Muirhead et al, 2012;Svensen et al, 2012Svensen et al, , 2015Jackson et al, 2013;Magee et al, 2014;Zhao et al, 2014;Button and Cawthorn, 2015;Schofield et al, 2015). Sill complexes imaged in seismic data and observed in the field extend laterally for tens to thousands of kilometers and are dominated by an interconnected network of mafic, relatively thin (typically <100 m thick) sills, which frequently exhibit saucer-shaped morphologies, and inclined sheets with only a small proportion of dikes (e.g., …”

Section: Introductionmentioning

confidence: 99%

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Lateral Magma Flow in Mafic Sill‐complexes

Magee

Muirhead

Karvelas

et al. 2016

Acta Geologica Sinica (Eng)

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The structure of upper crustal magma plumbing systems controls the distribution of volcanism and influences tectonic processes. However, delineating the structure and volume of plumbing systems is difficult because (1) active intrusion networks cannot be directly accessed; (2) field outcrops are commonly limited; and (3) geophysical data imaging the subsurface are restricted in areal extent and resolution. This has led to models involving the vertical transfer of magma via dikes, extending from a melt source to overlying reservoirs and eruption sites, being favored in the volcanic literature. However, while there is a wealth of evidence to support the occurrence of dike-dominated systems, we synthesize field-and seismic reflection-based observations and highlight that extensive lateral magma transport (as much as 4100 km) may occur within mafic sill complexes. Most of these mafic sill complexes occur in sedimentary basins (e.g., the Karoo Basin, South Africa), although some intrude crystalline continental crust (e.g., the Yilgarn craton, Australia), and consist of interconnected sills and inclined sheets. Sill complex emplacement is largely controlled by host-rock lithology and structure and the state of stress. We argue that plumbing systems need not be dominated by dikes and that magma can be transported within widespread sill complexes, promoting the development of volcanoes that do not overlie the melt source. However, the extent to which active volcanic systems and rifted margins are underlain by sill complexes remains poorly constrained, despite important implications for elucidating magmatic processes, melt volumes, and melt sources.

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Section: Constraining Magma Flow Patterns In Outcrop and Seismic Datamentioning

confidence: 99%

Section: Karoo-ferrar Lipmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lateral Magma Flow in Mafic Sill‐complexes

Magee

Muirhead

Karvelas

et al. 2016

Acta Geologica Sinica (Eng)

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“…Observations of igneous sills in this study and elsewhere in the western Pacific [e.g., Larson and Schlanger, 1981;Abrams et al, 1993; [e.g., Cartwright and Hansen, 2006;Muirhead et al, 2012]. In addition to pipe-like structures facilitating the focused transport of melt through the lithosphere and across the Moho, we suggest that there exists a broad spectrum of fingering melt networks ascending from a volumetrically large asthenospheric source that transports melt through the lithosphere to produce a wide range of igneous crustal features, from extrusive seamounts and flows to sills embedded within the crust (Fig.…”

Section: Wessel and Lyonsmentioning

confidence: 99%

Seismic constraints on the processes and consequences of secondary igneous evolution of Pacific oceanic lithosphere

Feng¹

2016

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This thesis examines the structure of Pacific oceanic lithosphere that has been modified by post-formation magmatism in order to better understand the processes of secondary magmatic evolution of the lithosphere, which can have global-scale implications for oceanic and atmospheric chemistry. In the western Pacific, widespread Cretaceous magmatism has modified oceanic lithosphere over hundreds of millions of square kilometers. Seismic models of the upper crust from within the Jurassic Quiet Zone and the crust and upper mantle near the Mariana Trench reveal crust that is locally thickened via focused extrusive volcanism and crust that is modestly but uniformly thickened over broad regions. These distinct modes of magmatic emplacement suggest the operation of both focused and diffuse modes of melt transport through the lithosphere. Analysis of seismic observations from Guaymas Basin, in the Gulf of California, endeavor to advance our understanding of sill-driven alteration of sediments, an important consequence of secondary magmatism. We show that seismically imaged physical disruption to sediments due to igneous sill intrusion can be related to changes in sediment physical properties that reflect alteration processes. We also show how sill thickness can be estimated, enabling alteration intensity to be related to sill thickness in a variety of settings.

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“…Inclined sheets are discordant to bedding with a dip range of 10 • -70 • (e.g. Muirhead et al, 2012;Marsh, 2015). Cone sheets can have sill-like and dyke-like geometries, tracking the imposed near-field stress axes related to a major intrusive body (e.g.…”

Section: Definitions For Sheet Intrusionsmentioning

confidence: 99%

Igneous sills record far-field and near-field stress interactions during volcano construction: Isle of Mull, Scotland

Stephens¹,

Walker²,

Healy³

et al. 2017

Preprint

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Sill emplacement is typically associated with horizontally mechanically layered host rocks in a nearhydrostatic far-field stress state, where contrasting mechanical properties across the layers promote transitions from dykes, or inclined sheets, to sills. We used detailed field observations from the Loch Scridain Sill Complex (Isle of Mull, UK), and mechanical models to show that layering is not always the dominant control on sill emplacement. The studied sills have consistently shallow dips (1 • -25 • ) and cut vertically bedded and foliated metamorphic basement rocks, and horizontally bedded cover sedimentary rocks and lavas. Horizontal and shallowly-dipping fractures in the host rock were intruded with vertical opening in all cases, whilst steeply-dipping discontinuities within the sequence (i.e. vertical fractures and foliation in the basement, and vertical polygonal joints in the lavas) were not intruded during sill emplacement. Mechanical models of slip tendency, dilation tendency, and fracture susceptibility for local and overall sill geometry data, support a radial horizontal compression during sill emplacement. Our models show that dykes and sills across Mull were emplaced during NW-SE horizontal shortening, related to a far-field tectonic stress state. The dykes generally accommodated phases of NE-SW horizontal tectonic extension, whereas the sills record the superposition of the far-field stress with a near-field stress state, imposed by emplacement of the Mull Central Volcano. We show that through detailed geometric characterisation coupled with mechanical modelling, sills may be used as an indication of fluctuations in the paleostress state.

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Interconnected sills and inclined sheet intrusions control shallow magma transport in the Ferrar large igneous province, Antarctica

Cited by 83 publications

References 93 publications

Lateral Magma Flow in Mafic Sill‐complexes

Lateral Magma Flow in Mafic Sill‐complexes

Seismic constraints on the processes and consequences of secondary igneous evolution of Pacific oceanic lithosphere

Igneous sills record far-field and near-field stress interactions during volcano construction: Isle of Mull, Scotland

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