3D relationships between sills and their feeders: evidence from the Golden Valley Sill Complex (Karoo Basin) and experimental modelling

Galerne, Christophe; Galland, Olivier; Neumann, Else-Ragnhild; Planke, Sverre

doi:10.1016/j.jvolgeores.2011.02.006

Cited by 84 publications

(55 citation statements)

References 46 publications

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“…Elongation of Alu parallel to the rift Table DR1 (sill and laccolith measurements) and Table DR2 (forced fold measurements) with the intrusion and forced fold lengths and thicknesses/amplitudes obtained from the literature and used in Figure 4, is available online at http://www.geosociety.org/datarepository/2017/ or on request from editing@geosociety.org. axis implies that the saucer-shaped sill could be dike fed (Galerne et al, 2011).…”

Section: Origin and Growth Of The Alu Dome And Surrounding Lava Fieldmentioning

confidence: 99%

Structure and dynamics of surface uplift induced by incremental sill emplacement

Magee

Bastow

Vries

et al. 2017

Geology

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Shallow-level sill emplacement can uplift Earth's surface via forced folding, providing insight into the location and size of potential volcanic eruptions. Linking the structure and dynamics of ground deformation to sill intrusion is thus critical in volcanic hazard assessment. This is challenging, however, because (1) active intrusions cannot be directly observed, meaning that we rely on transient host-rock deformation patterns to model their structure; and (2) where ancient sill-fold structure can be observed, magmatism and deformation has long since ceased. To address this problem, we combine structural and dynamic analyses of the Alu dome, Ethiopia, a 3.5-km-long, 346-m-high, elliptical dome of outward-dipping, tilted lava flows cross-cut by a series of normal faults. Vents distributed around Alu feed lava flows of different ages that radiate out from or deflect around its periphery. These observations, coupled with the absence of bounding faults or a central vent, imply that Alu is not a horst or a volcano, as previously thought, but is instead a forced fold. Interferometric synthetic aperture radar data captured a dynamic growth phase of Alu during a nearby eruption in A.D. 2008, with periods of uplift and subsidence previously attributed to intrusion of a tabular sill at 1 km depth. To localize volcanism beyond its periphery, we contend that Alu is the first forced fold to be recognized to be developing above an incrementally emplaced saucershaped sill, as opposed to a tabular sill or laccolith.

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Section: Origin and Growth Of The Alu Dome And Surrounding Lava Fieldmentioning

confidence: 99%

Structure and dynamics of surface uplift induced by incremental sill emplacement

Magee

Bastow

Vries

et al. 2017

Geology

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“…The extensive distribution of sill-sill junctions, which are a proxy for feeder relationships, implies that interconnected sills form efficient magma migration pathways (Cartwright and Hansen, 2006;Muirhead et al, 2012;Magee et al, 2014;Schofield et al, 2015). While sill-sill junctions may form via sill-sill abutment or crosscutting (Hansen et al, 2004;Galerne et al, 2011), as opposed to a feeding relationship, the mapping of flow patterns can help to constrain intrusion connectivity within sill complexes.…”

Section: Constraining Magma Flow Patterns In Outcrop and Seismic Datamentioning

confidence: 99%

“…While the source of numerous sill complexes remains poorly constrained, commonly due a paucity of seismic and/or borehole data in relevant areas, several studies have proposed that sill complexes may (1) originate from underlying melt zones (high-velocity bodies in seismic data) via dikes, fault-hosted intrusions, or transgressive sills (e.g., Figs. 10A, 10B, and 11C; e.g., Cartwright and Hansen, 2006;Galerne et al, 2011;Rohrman, 2013;Schofield et al, 2015); (2) be fed by laterally propagating dike swarms that emanate from volcanic centers or mantle plume heads (e.g., Hyndman and Alt, 1987;Ernst et al, 1995); (3) propagate directly away from volcanic centers (Magee et al, 2014;Neres et al, 2014); or (4) be sourced directly from a plume head, with lateral movement promoted by emplacement into an area of topographic uplift above the plume head and the generation of a hydraulic gradient sufficient enough to allow sills (<10 m thick) to flow laterally for thousands of kilometers without freezing (Fialko and Rubin, 1999;Aspler et al, 2002;Leat, 2008).…”

Section: Lateral Magma Flowmentioning

confidence: 99%

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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“…In addition, they are explored for hydrocarbons all over the world (e.g., Senger et al, forthcoming), onshore and offshore, e.g., the Rockall Basin (e.g., Magee et al, 2014), the Faroe-Shetland Basin (e.g., Smallwood and Maresh, 2002), the Møre and Vøring Basins (e.g., Planke et al, 2005;Cartwright and Hansen, 2006), and the Neuquén Basin (e.g., Kay et al, 2006). The magma plumbing systems in these basins are primarily dominated by interconnected networks of sill intrusions, the emplacement of which can significantly deform the host rock and influence petroleum system development (Kontorovich et al, 1997;Thomson and Hutton, 2004;Cartwright and Hansen, 2006;de Saint-Blanquat et al, 2006;Morgan et al, 2008;Galerne et al, 2011;Schofield et al, 2015;Magee et al, 2016;Wilson et al, 2016). For example, numerous studies have demonstrated that sill intrusions may (1) locally heat and mature organic matter within the host rock, generating oil and/or gas (e.g., Rodriguez Monreal et al, 2009), (2) be associated with 1 overlying dome structures that can be described as four-way dip closures Jackson et al, 2013;Magee et al, 2014Magee et al, , 2015, and (3) promote the development of local intense fracture networks that locally increase host rock permeability (Witte et al, 2012;Agirrezabala, 2015;Senger et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, distinct mechanisms controlling the formation of sill-associated doming have been proposed. The most common mechanism involves synemplacement uplift accommodating sill intrusion (e.g., Pollard and Johnson, 1973;Roman-Berdiel et al, 1995;Malthe-Sørenssen et al, 2004;Hansen and Cartwright, 2006;Kavanagh et al, 2006;Menand, 2008;Bunger and Cruden, 2011;Galerne et al, 2011;Galland, 2012;Galland et al, 2014Galland et al, , 2015. These models typically assume that uplift occurs via elastic bending, and sometimes failure, of the overburden, causing forced folding and fracturing due to the intrusion.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

et al. 2017

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The emplacement of igneous intrusions into sedimentary basins mechanically deforms the host rocks and causes hydrocarbon maturation. Existing models of host-rock deformation are investigated using high-quality 3D seismic and industry well data in the western Møre Basin offshore mid-Norway. The models include synemplacement (e.g., elastic bending-related active uplift and volume reduction of metamorphic aureoles) and postemplacement (e.g., differential compaction) mechanisms. We use the seismic interpretations of five horizons in the Cretaceous-Paleogene sequence (Springar, Tang, and Tare Formations) to analyze the host rock deformation induced by the emplacement of the underlying saucer-shaped Tulipan sill. The results show that the sill, emplaced between 55.8 and 54.9 Ma, is responsible for the overlying dome structure observed in the seismic data. Isochron maps of the deformed sediments, as well as deformation of the younger postemplacement sediments, document a good match between the spatial distribution of the dome and the periphery of the sill. The thickness t of the Tulipan is less than 100 m, whereas the amplitude f of the overlying dome ranges between 30 and 70 m. Spectral decomposition maps highlight the distribution of fractures in the upper part of the dome. These fractures are observed in between hydrothermal vent complexes in the outer parts of the dome structure. The 3D seismic horizon interpretation and volume rendering visualization of the Tulipan sill reveal fingers and an overall saucer-shaped geometry. We conclude that a combination of different mechanisms of overburden deformation, including (1) elastic bending, (2) shear failure, and (3) differential compaction, is responsible for the synemplacement formation and the postemplacement modification of the observed dome structure in the Tulipan area.

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3D relationships between sills and their feeders: evidence from the Golden Valley Sill Complex (Karoo Basin) and experimental modelling

Cited by 84 publications

References 46 publications

Structure and dynamics of surface uplift induced by incremental sill emplacement

Structure and dynamics of surface uplift induced by incremental sill emplacement

Lateral Magma Flow in Mafic Sill‐complexes

Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

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