Challenging dyke ascent models using novel laboratory experiments: Implications for reinterpreting evidence of magma ascent and volcanism

Kavanagh, Janine; Burns, Alec; Hazim, Suraya Hilmi; Wood, Elliot; Martin, Simon; Hignett, Sam; Dennis, David

doi:10.1016/j.jvolgeores.2018.01.002

Cited by 62 publications

(69 citation statements)

References 58 publications

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“…The general form of their dikes were similar to ours, albeit with greater thickness and distinct chilled margins. It is likely that the inner fluid core of the dike undergoes flow patterns similar to those observed in this studyand those described by Kavanagh et al (). Furthermore, we were able to replicate behaviors observed in nature, such as the heterogeneous solidification and the subsequent channelization of a dike.…”

Section: Discussionsupporting

confidence: 86%

“…It is important to consider that dikes have complex internal flow, which may affect how heat is distributed throughout the dike. Kavanagh et al () identified several stages of flow within a dike including: (1) initial injection and radial growth of a penny‐shaped crack, (2) growth and internal circulation of the magma, and (3) eruption and ejection of magma from the dike. The assumption that magma flows unidirectionally away from the source may not be true during the propagation stage of a dike and instead may only apply for syneruptive, channelized flow.…”

Section: Discussionmentioning

confidence: 99%

“…One way to check for this would be by measuring a time series of a fissure eruption's temperature distribution. Kavanagh et al () show that, prior to eruption, dikes can have an internal magma circulation, consisting of an upward central jet and lateral downward flow. As the dike breaches the surface, it contracts and squeezes much of the liquid upward onto the surface.…”

Section: Discussionmentioning

confidence: 99%

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Dike Channelization and Solidification: Time Scale Controls on the Geometry and Placement of Magma Migration Pathways

2019

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We investigate the conditions under which magma prefers to migrate through the crust via a dike or a conduit geometry. We performed a series of analogue experiments, repeatedly injecting warm, liquid gelatin, into a cold, solid gelatin medium and allowing the structure to evolve with time. We varied the liquid flux and the time interval between discrete injections of gelatin. The time interval controls the geometry of the migration, in that long intervals allow the intrusions to solidify, favoring the propagation of new dikes. Short time intervals allow the magma to channelize into a conduit. These times are characterized by the Fourier number (Fo), a ratio of time and thermal diffusion to dike thickness, so that long times scales have Fo > 102 and short time scales have Fo < 100. Between these time scales, a transitional behavior exists, in which new dikes nest inside of previous dikes. The flux controls the distance a dike can propagate before solidifying, in that high fluxes favor continual propagation, whereas low fluxes favor dike arrest due to solidification. For vertically propagating dikes, this indicates whether or not a dike can erupt. A transitional behavior exist, in which dikes may erupt at the surface in an unstable, on‐and‐off fashion. We supplemented the experimental findings with a 2‐D numerical model of thermal conduction to characterize the temperature gradient in the crust as a function of intrusion recurrence frequency. For very infrequent intrusions (Fo > 104 to 105) all thermal energy is lost, while more frequent intrusions allow heat to build up nearby.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Dike Channelization and Solidification: Time Scale Controls on the Geometry and Placement of Magma Migration Pathways

2019

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“…In 3dimensional gel models, resolving each fracture with polariscopy would be impossible because (1) structures can be out-of-plane with respect to the light source and (2) the light can cross several structures (e.g., Taisne and Tait, 2009). Another method used to image deformation in 3-dimensional gel experiments implements the tracking of particles in suspension in the gel and illuminated by a laser sheet (e.g., Kavanagh et al, 2015Kavanagh et al, , 2018. Nevertheless, the resolution of the digital image correlation for particle tracking is not enough to image sharp structures like the fractures we observe.…”

Section: Laboratory Methodsmentioning

confidence: 99%

Laboratory Modeling of Coeval Brittle and Ductile Deformation During Magma Emplacement Into Viscoelastic Rocks

et al. 2018

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“…There is a rich history of study into the emplacement of dikes and the dike to sill transition, via analog experiments (Johnson & Pollard, 1973; Kavanagh et al, 2015, 2018; Menand et al, 2010; Menand & Tait, 2002; Takada, 1990), analytical models (Pollard & Townsend, 2018), and numerical models (Barnett & Gudmundsson, 2014; Dahm, 2000; Gudmundsson, 2011; Pollard, 1973; Townsend et al, 2017). It has long been proposed that the geometry of dikes and hydraulic fractures is strongly controlled by the ambient regional stress field (e.g., Anderson, 1936; King Hubbert & Willis, 1959; Maccaferri et al, 2010; Sibson, 2000).…”

Section: Background and Methodsmentioning

confidence: 99%

The Roles of Elastic Properties, Magmatic Pressure, and Tectonic Stress in Saucer‐Shaped Sill Growth

Gill

Walker

2020

JGR Solid Earth

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Near-surface igneous sills commonly exhibit saucer-like shapes, formed due to interaction with the Earth's surface once some critical sill length is reached relative to its depth. Sill geometry has been strongly linked to the host material conditions, particularly in terms of the elastic properties and shear cohesion of the host rock, operating as primary controls on sill geometry. Here we conduct dynamic numerical simulations for sill growth in the near surface, in which we vary the host rock properties, magma pressure profile internal to the sill ΔP, and the externally applied tectonic stress σ r , to consider their contributions to sill geometry. We find that elastic properties alone have little impact on sill geometry. Saucer shapes reflect the additive stress components of the magma overpressure within the sill, and the tectonic stress, controlled by the locus of the maximum energy release rate G max . Initially, G max is in-plane with the sill but deflects to~25°at a critical base length r c relative to depth, due to interaction between the sill and the free surface. Increasing σ r decreases this angle and increases r c of the sill. ΔP controls sill growth rate but has little effect on overall geometry. Host rock cohesion and elastic properties control the absolute magnitudes of σ r required to effect a change in sill geometry.Plain Language Summary Horizontal magma pathways-sills-are a crucial part of volcanic plumbing systems, acting as potential feeder conduits to volcanic eruptions, and as magma storage systems. Saucer-shaped sills, which exhibit a flat inner region and inclined outer region, are a common type of magma pathway in the shallow crust. Models for saucer-shaped sills, both as physical analog models or numerical simulations, typically underpredict the length of the inner flat region and overpredict the outer inclined region; models are typically too short and too steep. Here we use numerical simulation to investigate parameters that may control sill shape. We find that the dominant controls on sill shape are the competing effects of (1) bending of the rocks above the sill, which promotes a transition to inclined growth, typically at~25°, and (2) plate tectonic shortening, which serves to decrease the angle of incline, toward 0°when the horizontal force is high. Increasing the applied horizontal tectonic force can produce sills that are up to five times longer in the inner region, before growing as inclined sills at~5°. This matches very closely with observations of natural sills, indicating that tectonic forces are an important consideration in the growth of sills.

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Challenging dyke ascent models using novel laboratory experiments: Implications for reinterpreting evidence of magma ascent and volcanism

Cited by 62 publications

References 58 publications

Dike Channelization and Solidification: Time Scale Controls on the Geometry and Placement of Magma Migration Pathways

Dike Channelization and Solidification: Time Scale Controls on the Geometry and Placement of Magma Migration Pathways

Laboratory Modeling of Coeval Brittle and Ductile Deformation During Magma Emplacement Into Viscoelastic Rocks

The Roles of Elastic Properties, Magmatic Pressure, and Tectonic Stress in Saucer‐Shaped Sill Growth

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