Saucers, Fingers, and Lobes: New Insights on Sill Emplacement From Scaled Laboratory Experiments

Arachchige, Uchitha Suranga Nissanka; Cruden, Alexander; Weinberg, Roberto Ferrez; Slim, Anja C.; Köpping, Jonas

doi:10.1029/2022jb024421

Cited by 8 publications

(16 citation statements)

References 82 publications

(317 reference statements)

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“…These model material combinations reproduced intrusion structures observed in geological settings. In addition, they provide appropriate scaling of the model properties to nature and the values of dimensionless model parameters satisfying the Buckingham‐Π theorem (Arachchige et al., 2022; Merle, 2015).…”

Section: Laboratory Experimentsmentioning

confidence: 99%

“… a Natural values: (Arachchige et al., 2022; Galland et al., 2014; Gerbi et al., 2004; Head et al., 2021; Mandal et al., 2018; Poppe et al., 2019; Sen et al., 2023; S. Takeuchi & Nakamura, 2001; Wang et al., 2021). …”

Section: Laboratory Experimentsmentioning

confidence: 99%

“…The rectangular glass box was filled with the host (USTG or gel wax) material, leaving the top surface unconfined to accommodate the liquid volume injected into the host. One of the side glass walls (XZ side: 18 cm × 14 cm) had a tiny hole, which was sealed with a soft sticking sheet at the time of model preparation that the needle of a Nature is 10 5 times stronger than the model a Natural values: (Arachchige et al, 2022;Galland et al, 2014;Gerbi et al, 2004;Head et al, 2021;Mandal et al, 2018;Poppe et al, 2019;Sen et al, 2023;S. Takeuchi & Nakamura, 2001;Wang et al, 2021).…”

Section: Experimental Designmentioning

confidence: 99%

See 2 more Smart Citations

Wall Fracturing Versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights From Laboratory Experiments

Biswas,

Mitra,

Mandal

2023

JGR Solid Earth

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Igneous dike intrusion is a primary crust‐forming process at the Earth's plate boundaries. Understanding its mechanism is thus crucially important in lithospheric studies. Our present article combines experimental and field observations to investigate the problem of dike emplacement from a mechanical perspective. Scaled laboratory experiments were conducted by injecting immiscible liquids into visco‐elastic and visco‐elasto‐plastic host materials at varying volumetric flow rates (VFR = 0.100 to 1.670 ml s−1). Another set of experiments used different injecting liquid–host combinations to set their viscosity ratios (η*) at low (105), moderate (106), and high (109) values. These two lines of experiments allow us to recognize three principal mechanisms of liquid pathways: tensile fracturing of the host, wave instability at the liquid‐host interface, and coupled fracturing‐wave instability process. The three mechanisms give rise to a wide variation in intrusion geometry, ranging from planar structures with elliptical outlines to typical bulbous geometry, with intermediate patterns characterized by in‐plane and off‐plane wavy interfaces with the host. This study uses the experimental data to constrain the VFR conditions that determine the fracturing versus wave instability‐controlled mechanisms. It is also shown from the experiments that η* can significantly influence the evolution of three‐dimensional intrusive geometry. The Chotonagpur Granite Gneiss Complex in eastern India is chosen as a field study area to validate our laboratory findings using a 2D shape analysis of the intrusive boundaries in terms of their fractal dimensions (D) and skewness‐kurtosis estimates.

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Section: Laboratory Experimentsmentioning

confidence: 99%

Section: Laboratory Experimentsmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

See 1 more Smart Citation

Wall Fracturing Versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights From Laboratory Experiments

Biswas,

Mitra,

Mandal

2023

JGR Solid Earth

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“…The co‐occurrence of tapered tips and tensile fracture opening with blunt tips and shear‐mode fracturing at some outcrops documents a mixed‐mode magma propagation mechanism (e.g., Kjøll et al., 2019; Poppe et al., 2020). More complex fluidization, viscous fingering and other mixed‐mode mechanisms have been documented as well (e.g., Arachchige et al., 2022; Bertelsen et al., 2021; Schofield et al., 2010).…”

Section: Introductionmentioning

confidence: 95%

Inversions of Surface Displacements in Scaled Experiments of Analog Magma Intrusion

Poppe,

Wauthier,

Fontijn

2024

Geophysical Research Letters

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Standard geodetic models simplify magma sheet injection to the opening of geometrically simple dislocations in a linearly elastic, homogeneous medium. Intrusion geometries are often complex, however, and non‐elastic deformation mechanisms can dominate the response of heterogeneous rocks to magma‐induced stresses. We used three‐dimensional near‐surface displacements of a scaled laboratory experiment in which a steeply inclined analog magma sheet was injected into granular material. We ran forward models and inverted for eight parameters of an “Okada‐type” tensile rectangular dislocation in a homogeneous, isotropic, and linearly elastic half‐space. Displacements generated by a forward model largely mismatch the experimental displacements, but full or restricted non‐linear inversions of geometrical parameters reduce the residual displacements. The intrusion opening, dip, depth, and to a lesser degree length and width mismatch the most between the experiment and inversion results, whereas location and strike mismatch the least. Our results challenge assumptions made by many analytical and geodetic models.

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“…Theoretical (Pollard et al, 1982;Bruce and Huppert, 1989;Lister and Dellar, 1996;Bolchover and Lister, 1999) and numerical (Rubin, 1993) studies of the effects of magma solidification during emplacement of dykes and sills are limited to two-dimensions. Most three-dimensional (3D) magma intrusion laboratory experiments have so far used isothermal magma analogues (e.g., Kavanagh et al, 2006;Galland et al, 2009;Arachchige et al, 2022) due to practical challenges in using analogue materials capable of simulating magma solidification. Using gelatine and molten paraffin wax as crustal rock and magma analogues, respectively, Taisne and Tait (2011) were the first to experimentally investigate 3D solidification effects during the propagation of dykes.…”

Section: Introductionmentioning

confidence: 99%

Magma solidification effects during sill emplacement: insights from laboratory experiments

Arachchige,

Cruden,

Weinberg

2024

Preprint

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Igneous sills and interconnected sill complexes transport magma both vertically through the Earth’s crust and laterally over potentially long distances. Although cooling and solidification of magma are acknowledged to play a major role in the propagation and emplacement of sills, their contributions to sill formation remain poorly understood. Here, the effects of solidification on sill propagation dynamics and the resulting intrusion morphologies are investigated using scaled laboratory experiments. Hot coconut oil (magma analogue) that solidifies during emplacement is injected as a sill into a colder, layered, solid visco-elasto-plastic gel (Laponite RD®, host rock analogue). Molten coconut oil is injected directly into the horizontal interface between two Laponite RD® layers to facilitate sill formation. The injection temperature and volumetric flow rate of the coconut oil are systematically varied between experiments in order to vary the degree of solidification. When solidification effects are relatively weak (high injection temperatures), sill propagation is continuous and forms penny-shaped intrusions that later turn into saucer-shaped sills with marginal segmentation. Conversely, when solidification effects are intermediate to relatively strong (low injection temperatures), sills develop complex elongate morphologies that lengthen parallel to the long-axis of the magma flow direction. Such sills also form in a discontinuous manner and propagate in pulses by growth of discrete marginal lobes, representing periods of tip arrest due to freezing, followed by growth of new lobes at the sill margins. A striking morphological feature that occurs in experiments with intermediate to relatively strong solidification effects is the presence of internal flow channels within sills, which can be: (a) thermally controlled, long-lived channels in intermediate solidification experiments; or (b) structurally controlled, randomly oriented short-lived channels in strong solidification experiments. Our experimental findings are consistent with field and seismic observations of sill geometries, and they highlight that the relative degree of solidification during magma emplacement controls both how sills propagate and their internal flow dynamics.

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Saucers, Fingers, and Lobes: New Insights on Sill Emplacement From Scaled Laboratory Experiments

Cited by 8 publications

References 82 publications

Wall Fracturing Versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights From Laboratory Experiments

Wall Fracturing Versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights From Laboratory Experiments

Inversions of Surface Displacements in Scaled Experiments of Analog Magma Intrusion

Magma solidification effects during sill emplacement: insights from laboratory experiments

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