Geometry and controls on the development of igneous sill-related forced folds: A 2-D seismic reflection case study from offshore southern Australia

Jackson, Christopher; Schofield, Nick; Golenkov, Bogdan

doi:10.1130/b30833.1

Cited by 137 publications

(211 citation statements)

References 39 publications

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“…It is difficult to link Early Pliocene sill emplacement (5-4 Ma) to other magmatic events that occurred in and around the Canterbury Basin, although it may relate the~2.6 Myr old basaltic Geraldine and Timaru lavas [Timm et al 2010]. Jackson et al 2013;Magee et al 2013]. To date, however, the vast majority of seismic-based studies examining intrusion-induced forced folds adopt an interpretation framework that assumes magma emplacement and fold growth occurred instantaneously [e.g.…”

Section: Tectono-magmatic Contextmentioning

confidence: 99%

“…Whilst many previous seismic-based studies have not recognised reverse faults associated with forced folding [e.g. 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].…”

Section: Fold Amplitude As a Proxy For Sill Thicknessmentioning

confidence: 99%

“…fluidisation and porosity reduction), fold amplitude will be less than the thickness of the intrusion [e.g. Jackson et al 2013;Magee et al 2013;Magee et al 2017b]. …”

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%

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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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Section: Tectono-magmatic Contextmentioning

confidence: 99%

Section: Fold Amplitude As a Proxy For Sill Thicknessmentioning

confidence: 99%

“…fluidisation and porosity reduction), fold amplitude will be less than the thickness of the intrusion [e.g. Jackson et al 2013;Magee et al 2013;Magee et al 2017b]. …”

Section: Fold Amplitude As a Proxy For Sill Thicknessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2018

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“…Since this work, new seismic datasets have been acquired and improvements in techniques and understanding of volcanic geometries have increased our understanding of igneous rocks in hydrocarbon systems (e.g. Jackson et al (2013), , Schofield et al (2012)). …”

Section: Introductionmentioning

confidence: 99%

Characterising extrusive and intrusive magmatism at the Kipper Field, Gippsland Basin, using 3D seismic data

Meeuws

Reynolds

Holford

et al. 2016

ASEG Extended Abstracts

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SUMMARYIncreased hydrocarbon exploration along rifted continental margins indicates the need of a better understanding of the impact and influence of igneous rocks on hydrocarbon systems as they are often present in these tectonic settings. The southern Australian margin contains several petroliferous sedimentary basins which contain Cretaceous-Cenozoic igneous rocks and is therefore an ideal study area to investigate both the positive and negative effects on hydrocarbon systems. In particular, the Kipper Field in the offshore Gippsland Basin forms an excellent example of a volcanic play, as it holds a 328 m gas column and 14 m oil leg sealed by a >100 m thick basaltic lava flow juxtaposed against a sealing fault. The basin also contains a number of cross-cutting and layer-parallel type intrusions, although their impact on the petroleum system is as-yet unclear. Seismic interpretation techniques such as spectral decomposition and opacity rendering combined with electrical log signatures allowed us to identify the lava flow and intrusions down dip from the fault. Whether this fault has acted as a conduit for the magma responsible for the lava flow is still unclear. Future work will aim to further delineate and constrain flow paths of the intrusive and extrusive rocks near the Kipper Field and their influence on the Kipper play. This study highlights the importance of volcanic rocks in hydrocarbon basins and the possible effect they can have on hydrocarbon systems.

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Inelastic deformation during sill and laccolith emplacement: Insights from an analytic elastoplastic model

2017

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Numerous geological observations evidence that inelastic deformation occurs during sills and laccoliths emplacement. However, most models of sill and laccolith emplacement neglect inelastic processes by assuming purely elastic deformation of the host rock. This assumption has never been tested so that the role of inelastic deformation on the growth dynamics of magma intrusions remains poorly understood. In this paper, we introduce the first analytical model of shallow sill and laccolith emplacement that accounts for elastoplastic deformation of the host rock. It considers the intrusion's overburden as a thin elastic bending plate attached to an elastic‐perfectly plastic foundation. We find that, for geologically realistic values of the model parameters, the horizontal extent of the plastic zone lp is much smaller than the radius of the intrusion a. By modeling the quasi‐static growth of a sill, we find that the ratio lp/a decreases during propagation, as 1/a4ΔP, with ΔP the magma overpressure. The model also shows that the extent of the plastic zone decreases with the intrusion's depth, while it increases if the host rock is weaker. Comparison between our elastoplastic model and existing purely elastic models shows that plasticity can have a significant effect on intrusion propagation dynamics, with, e.g., up to a doubling of the overpressure necessary for the sill to grow. Our results suggest that plasticity effects might be small for large sills but conversely that they might be substantial for early sill propagation.

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Geometry and controls on the development of igneous sill-related forced folds: A 2-D seismic reflection case study from offshore southern Australia

Cited by 137 publications

References 39 publications

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

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

Characterising extrusive and intrusive magmatism at the Kipper Field, Gippsland Basin, using 3D seismic data

Inelastic deformation during sill and laccolith emplacement: Insights from an analytic elastoplastic model

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