Forced folding above shallow magma intrusions: Insights on supercritical fluid flow from analogue modelling

Montanari, Domenico; Bonini, Marco; Corti, Giacomo; Agostini, Andrea; Ventisette, Chiara Del

doi:10.1016/j.jvolgeores.2017.07.022

Cited by 63 publications

(87 citation statements)

References 64 publications

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“…Shear damage associated with the emplacement of sills and laccoliths has been observed in the field, both in sedimentary settings (e.g., de Saint‐Blanquat et al, ; Pollard, ; Spacapan et al, ; Wilson et al, ) and in basaltic volcanoes (e.g., Berthod et al, ; Got et al, ). In addition, laboratory models of sill emplacement in the Coulomb brittle crust strongly suggest that plastic shear damage is likely controlling the emplacement of magma (Galland, ; Galland et al, ; Galland et al, ; Montanari et al, ; Guldstrand et al, ; Schmiedel, Galland, & Breitkreuz, ). However, most models of sills and laccolith emplacement assume that plastic failure is restricted to small process zones at the close vicinity of sill's tips and can be neglected (e.g., Bunger & Cruden, ; Cruden et al, ; Kavanagh et al, ; Michaut, ; Rivalta et al, ; Rubin, ; Thorey & Michaut, ); this assumption is the main foundation for the majority of the state‐of‐the‐art mechanical models of sheet intrusion emplacement, which account for purely elastic host rock deformation.…”

Section: Discussionmentioning

confidence: 99%

Shear Versus Tensile Failure Mechanisms Induced by Sill Intrusions: Implications for Emplacement of Conical and Saucer‐Shaped Intrusions

et al. 2018

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Sills, saucer‐shaped sills, and cone sheets are fundamental magma conduits in many sedimentary basins worldwide. Models of their emplacement usually approximate the host rock properties as purely elastic and consider the plastic deformation to be negligible. However, many field observations suggest that inelastic damage and shear fracturing play a significant role during sill emplacement. Here we use a rigid plasticity approach, through limit analysis modeling, to study the conditions required for inelastic deformation of sill overburdens. Our models produce distinct shear failure structures that resemble intrusive bodies, such as cone sheets and saucer‐shaped sills. This suggests that shear damage greatly controls the transition from flat sill to inclined sheets. We derive an empirical scaling law of the critical overpressure required for shear failure of the sill's overburden. This scaling law allows to predict the critical sill diameter at which shear failure of the overburden occurs, which matches the diameters of natural saucer‐shaped intrusions' inner sills. A quantitative comparison between our shear failure model and the established sill's tensile propagation mechanism suggests that sills initially propagate as tensile fractures, until reaching a critical diameter at which shear failure of the overburden controls the subsequent emplacement of the magma. This comparison also allows us to predict, for the first time, the conditions of emplacement of both conical intrusions, saucer‐shaped intrusions, and large concordant sills. Beyond the application to sills, our study suggests that shear failure significantly controls the emplacement of igneous sheet intrusions in the Earth's brittle crust.

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Section: Discussionmentioning

confidence: 99%

Shear Versus Tensile Failure Mechanisms Induced by Sill Intrusions: Implications for Emplacement of Conical and Saucer‐Shaped Intrusions

et al. 2018

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“…Trude et al 2003;Hansen et al 2008;Jackson et al 2013;Magee et al 2013], analogue modelling experiments show that reverse faults can accompany forced fold formation [e.g. Galetto et al 2017;Montanari et al 2017]. With inflation and bending of the overburden, eventual tensile fracturing of the host rock immediately overlying the lateral terminations of the tabular sill allows magma to transgress upwards and form the inclined limbs of a widening saucer-shaped sill ( Figure 12B; Time 1).…”

Section: Fold Amplitude As a Proxy For Sill Thicknessmentioning

confidence: 99%

“…faulting, fluidisation, and pore collapse) can accommodate magma emplacement [e.g. Pollard and Johnson 1973;Johnson 1987;Galland and Scheibert 2013;Jackson et al 2013;Magee et al 2013;van Wyk de Vries et al 2014;Montanari et al 2017]. The likely occurrence of inelastic deformation processes implies that traditional inversion of ground deformation data Corresponding author: c.magee@imperial.ac.uk assuming pure elastic bending of the host rock will underestimate magma volumes [e.g.…”

Section: Introductionmentioning

confidence: 99%

Unravelling intrusion-induced forced fold kinematics and ground deformation using 3D seismic reflection data

2018

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Sills emplaced at shallow-levels are commonly accommodated by overburden uplift, producing forced folds. We examine ancient forced folds developed above saucer-shaped sills using 3D seismic reflection data from the Canterbury Basin, offshore SE New Zealand. Seismic-stratigraphic relationships indicate sill emplacement occurred incrementally over~31 Myr between the Oligocene (~35-32 Ma) and Early Pliocene (~5-4 Ma). Two folds display flat-topped geometries and amplitudes that decrease upwards, conforming to expected models of forced fold growth. Conversely, two folds display amplitudes that locally increase upwards, coincident with a transition from flat-topped to dome-shaped morphologies and an across-fold thickening of strata. We suggest these discrepancies between observed and expected forced fold geometry reflect uplift and subsidence cycles driven by sill inflation and deflation. Unravelling these forced fold kinematic histories shows complex intrusion geometries can produce relatively simple ground deformation patterns, where magma transgression corresponds to localisation of uplift.

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“…These interpretations are supported by observations from sedimentary basins elsewhere (e.g. Planke et al, 2005;Hansen and Cartwright, 2006;Blanke, 2012;Holford et al, 2012;Muirhead et al, 2016;Barrier et al, 2017;McLean et al, 2017;Schmiedel et al, 2017;Senger et al, 2017) and by laboratory experiments (Montanari et al, 2017).…”

Section: Mvs Plumbing-typesmentioning

confidence: 58%

Stratigraphy of Architectural Elements of a Buried Monogenetic Volcanic System and Implications for Geoenergy Exploration

Bischoff¹,

Nicol²,

Cole³

et al. 2019

Preprint

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Large volumes of magma emplaced and deposited within sedimentary basins can have an impact on their architectural style and geological evolution. Over the last decade, continuous improvement in techniques such as seismic volcano-stratigraphy and 3D seismic visualization of igneous rocks buried in sedimentary basins has helped increase knowledge about these “volcanic basins”. Here, we unravel the complete architecture of the Maahunui Volcanic System (MVS), a middle Miocene monogenetic volcanic field now buried in the offshore Canterbury Basin, South Island of New Zealand. We show the location, geometry, size, and stratigraphic relationships between 25 main intrusive, eruptive, and sedimentary architectural elements in a comprehensive volcano-stratigraphic framework that explains the evolution of the MVS from emplacement to complete burial. The plumbing system of the MVS comprises of seven main architectural elements, including saucer-shaped sills, dikes and sills swarms, minor stocks and laccoliths, and pre-eruptive strata deformed by intrusions. These endogenous elements occur in five distinctive plumbing-types, controlled by the emplacement depth, and by the geometric relationships between the intrusions and the enclosing strata. The exogenous volcanic architecture is defined by a combination of eruptive and associated sedimentary architectural elements, with minor and localized shallow intrusions. Characteristic volcano-types of the MVS are interpreted as the deep-water equivalents of crater and cone-type volcanoes. Crater-type volcanoes have eight main architectural elements (i.e. root zone, lower and upper diatreme, tephra ring, tephra plain, intra-crater cones, overspill wedge and tephra fallow carpet). Cone-type volcanoes have five main architectural elements (i.e. basal cone, central crater, tephra flank, cone apron and tephra fallout carpet). After volcanism has ceased, the process of degradation and burial of the volcanic edifices produces five main sedimentary architectural elements (i.e. inter-cone plains, epiclastic plumes, canyons and gullies, burial domes and seamount-edge fans). Understanding the relationships between these diverse architectural elements allow us to reconstruct the complete architecture of the MVS, and to recognize the main volcano-stratigraphic trends in the study area. The characterisation of architectural elements of the MVS can be applied to explore opportunities to find valuable geoenergy resources such as oil, gas and geothermal energy with buried and active monogenetic volcanic systems.

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Forced folding above shallow magma intrusions: Insights on supercritical fluid flow from analogue modelling

Cited by 63 publications

References 64 publications

Shear Versus Tensile Failure Mechanisms Induced by Sill Intrusions: Implications for Emplacement of Conical and Saucer‐Shaped Intrusions

Shear Versus Tensile Failure Mechanisms Induced by Sill Intrusions: Implications for Emplacement of Conical and Saucer‐Shaped Intrusions

Unravelling intrusion-induced forced fold kinematics and ground deformation using 3D seismic reflection data

Stratigraphy of Architectural Elements of a Buried Monogenetic Volcanic System and Implications for Geoenergy Exploration

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