Determining magma flow in sills, dykes and laccoliths and their implications for sill emplacement mechanisms

Thomson, Katie

doi:10.1007/s00445-007-0131-8

Cited by 112 publications

(72 citation statements)

References 53 publications

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“…We avoided interpreting as sills 80 pronounced "smiles" that could be artifacts due to migration of off-plane seafloor 81 scattering. Some of our interpreted sills have a moderate "smile" shape, which could be 82 due to overmigration because of uncertainties in the velocity model, or a true geological 83 shape, as concave-up or saucer-shaped magmatic sills are common in a variety of 84 geological settings (e.g., Schofield et al, 2010; Thomson, 2007). 85…”

Section: Data Repository 1 ) 124mentioning

confidence: 96%

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Canales

Dunn

Arai

et al. 2017

Geology

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10Hydrothermal circulation at mid-ocean ridge volcanic segments extracts heat from 11 crustal magma bodies. However, the heat source driving hydrothermal circulation in 12 ultramafic outcrops, where mantle rocks are exhumed in low-magma supply 13 environments, has remained enigmatic. Here we use a three-dimensional P-wave velocity 14 model derived from active-source wide-angle refraction/reflection ocean bottom 15 seismometer data and pre-stack depth-migrated images derived from multichannel 16 seismic reflection data to investigate the internal structure of the Rainbow ultramafic 17 massif, which is located in a non-transform discontinuity of the Mid-Atlantic Ridge. 18Seismic imaging reveals that the ultramafic rocks composing the Rainbow massif have 19 been intruded by a large number of magmatic sills, distributed throughout the massif at 20 depths of ~2-10 km. These sills, which appear to be at varying stages of crystallization, 21can supply the heat needed to drive high-temperature hydrothermal circulation, and thus 22

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Section: Data Repository 1 ) 124mentioning

confidence: 96%

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Canales

Dunn

Arai

et al. 2017

Geology

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“…One limitation of seismic data is that subvertical dikes are rarely imaged (e.g., Thomson, 2007). The lack of dike imaging, which is attributed to the low amount of acoustic energy that reflects back to the surface off the subvertical wall of a dike, therefore biases seismic-based interpretations of plumbing systems.…”

Section: Application Of Seismic Reflection Data To Understanding Plummentioning

confidence: 99%

“…Dolerite dikes are typically 5-30 m wide, 50-300 km long, and trend mainly east to northeast, while sills recognized at the surface are as much as 50 m thick and 300 km in length . The Widgie mooltha and Marnda Moorn LIPs are generally characterized by dike suites that are not evident in the seismic data due to their steeper dips (Thomson, 2007), and thus the intrusions identified in the Youanmi seismic lines are interpreted to belong to the ca. 1070 Ma Warakurna LIP .…”

Section: Northern Yilgarn Craton Western Australiamentioning

confidence: 99%

“…The lack of dike imaging, which is attributed to the low amount of acoustic energy that reflects back to the surface off the subvertical wall of a dike, therefore biases seismic-based interpretations of plumbing systems. The role of dikes within sill complexes can, however, be investigated from (1) field analyses (e.g., Muirhead et al, 2014); (2) the interpretation of subvertical chaotic zones of reflection in seismic data as dikes (Thomson, 2007;Wall et al, 2010); and (3) the mapping of magma flow patterns in sills to identify potential dike feeders (see following). Through the careful application of these techniques and by comparison to field observations, seismic data can be used to delimit magma plumbing systems in more detail than field or other geophysical techniques.…”

Section: Application Of Seismic Reflection Data To Understanding Plummentioning

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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“…The field examples recorded within this study, however, comprise, to our knowledge, the first documented occurrences of hydrothermal vents, closely linked to the intrusions responsible for their formation, breaching an overlying volcanic sequence. Given the challenges associated with imaging features and structures beneath the volcanic cover from offshore (Thompson [2007] provides some examples), (Planke et al, 2005).…”

Section: Hydrothermal Vent Formation Processmentioning

confidence: 99%

Mafic intrusions, hydrothermal venting, and the basalt-sediment transition: Linking onshore and offshore examples from the North Atlantic igneous province

et al. 2017

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The emplacement of large intrusive complexes into sedimentary basins can have profound effects on host sedimentary rocks including deformation, thermal aureole metamorphic reactions, alteration of fluid-flow pathways, and the formation of associated hydrothermal vent complexes (HVCs). These processes can in turn have major implications for petroleum systems on the local and regional scale, and can contribute to global climate change due to the production and outgassing of greenhouse gases, such as CH 4 and CO 2 . Imaging these features and assessing their implications from seismic data beneath extrusive volcanic cover is challenging due to heterogeneities in the volcanic pile and at the basalt-sediment transition. We have evaluated combined field and laboratory petrophysical data from the Isle of Skye, Scotland, where we identify a seismic-scale example of extensive intrusions interacting with the base-basalt transition. We have also evaluated a unique onshore example of a linked sill and associated HVC cutting up through the lava sequence. We compare these field results with HVCs from reflection seismic data across the Vøring Marginal High, offshore Norway, where subbasalt saucer-shaped intrusions are also seen associated with HVCs cutting the lava sequence. Seismic imaging problems associated with the velocity heterogeneity of volcanic sequences, along with a historical lack of highquality 3D data in volcanic regions worldwide, is suggested as having largely precluded the identification of these features in the past. The under-representation of these hydrothermal vents in the literature has key implications for the future appraisal of intrusion-related outgassing effects on the global climate such as those related to the Palaeocene Eocene Thermal Maximum, along with subbasalt petroleum prospectivity where they may alter maturation and migration pathways.

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Determining magma flow in sills, dykes and laccoliths and their implications for sill emplacement mechanisms

Cited by 112 publications

References 53 publications

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Lateral Magma Flow in Mafic Sill‐complexes

Mafic intrusions, hydrothermal venting, and the basalt-sediment transition: Linking onshore and offshore examples from the North Atlantic igneous province

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