Large igneous provinces (LIPs), giant dyke swarms, and mantle plumes: significance for breakup events within Canada and adjacent regions from 2.5 Ga to the  PresentThis article is one of a selection of papers published in this Special Issue on the the theme <i>Lithoprobe—parameters, processes, and the evolution of a continent</i>.Lithoprobe Contribution 1482. Geological Survey of Canada Contribution 20100072.

Ernst, Richard E.; Bleeker, Wouter

doi:10.1139/e10-025

Cited by 355 publications

(53 citation statements)

References 215 publications

(318 reference statements)

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“…Baptiste et al [2012] also speculated that metasomatism would occur episodically, which would induce lateral heterogeneities within affected areas. The Superior Craton is pervaded by multiple dyke swarms that record magmatic pulses at 2.5, 2.2, and 2.1 Ga, linked with episodes of extension at the paleocratonic margins [Ernst and Bleeker, 2010] or the arrival of mantle plume heads [Ernst and Bleeker, 2001], providing possible metasomatic sources. Geochemical data in the Slave Craton [Griffin et al, 2004] suggest the presence of a second uniform Archean mantle layer, with the top located between 140 and 160 km depth.…”

Section: Hypotheses Of Formation and Age Of The Lower Lithospherementioning

confidence: 99%

Seismic anisotropy of Precambrian lithosphere: Insights from Rayleigh wave tomography of the eastern Superior Craton

et al. 2017

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The thick, seismically fast lithospheric keels underlying continental cores (cratons) are thought to have formed in the Precambrian and resisted subsequent tectonic destruction. A consensus is emerging from a variety of disciplines that keels are vertically stratified, but the processes that led to their development remain uncertain. Eastern Canada is a natural laboratory to study Precambrian lithospheric formation and evolution. It comprises the largest Archean craton in the world, the Superior Craton, surrounded by multiple Proterozoic orogenic belts. To investigate its lithospheric structure, we construct a frequency‐dependent anisotropic seismic model of the region using Rayleigh waves from teleseismic earthquakes recorded at broadband seismic stations across eastern Canada. The joint interpretation of phase velocity heterogeneity and azimuthal anisotropy patterns reveals a seismically fast and anisotropically complex Superior Craton. The upper lithosphere records fossilized Archean tectonic deformation: anisotropic patterns align with the orientation of the main tectonic boundaries at periods ≤110 s. This implies that cratonic blocks were strong enough to sustain plate‐scale deformation during collision at 2.5 Ga. Cratonic lithosphere with fossil anisotropy partially extends beneath adjacent Proterozoic belts. At periods sensitive to the lower lithosphere, we detect fast, more homogenous, and weakly anisotropic material, documenting postassembly lithospheric growth, possibly in a slow or stagnant convection regime. A heterogeneous, anisotropic transitional zone may also be present at the base of the keel. The detection of multiple lithospheric fabrics at different periods with distinct tectonic origins supports growing evidence that cratonization processes may be episodic and are not exclusively an Archean phenomenon.

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Section: Hypotheses Of Formation and Age Of The Lower Lithospherementioning

confidence: 99%

Seismic anisotropy of Precambrian lithosphere: Insights from Rayleigh wave tomography of the eastern Superior Craton

et al. 2017

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“…Also, multiple dyke swarms of different ages pervade the Superior Craton. Dyke complexes record magmatic pulses at 2.5, 2.2, and 2.1 Ga that are linked with many episodes of extension at the paleocratonic margins of Laurentia [Ernst and Bleeker, 2010]. However, no indication of recent tectonism has been detected within the subprovinces La Grande, Nemiscau, and the metaplutonic Opatica.…”

Section: Precambrian Crustal Properties: Original or Reset Signatures?mentioning

confidence: 99%

“…It could represent stacked volcanic sequences, erupted on top of a now buried homogeneous Archean basement. The CHGQ structure might be evidence for intense magmatic activity at the cratonic margin, which is the locus for several attempted rifting episodes [Ernst and Bleeker, 2010] and preexisting zones of weakness, reactivated during multiple Wilson cycles [e.g., Martignole and Calvert, 1996].…”

Section: 1002/2015jb012348mentioning

confidence: 99%

Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions

et al. 2016

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The geological record of SE Canada spans more than 2.5 Ga, making it a natural laboratory for the study of crustal formation and evolution over time. We estimate the crustal thickness, Poisson's ratio, a proxy for bulk crustal composition, and shear velocity (Vs) structure from receiver functions at a network of seismograph stations recently deployed across the Archean Superior Craton, the Proterozoic Grenville, and the Phanerozoic Appalachian provinces. The bulk seismic crustal properties and shear velocity structure reveal a correlation with tectonic provinces of different ages: the post‐Archean crust becomes thicker, faster, more heterogeneous, and more compositionally evolved. This secular variation pattern is consistent with a growing consensus that crustal growth efficiency increased at the end of the Archean. A lack of correlation among elevation, Moho topography, and gravity anomalies within the Proterozoic belt is better explained by buoyant mantle support rather than by compositional variations driven by lower crustal metamorphic reactions. A ubiquitous ∼20 km thick high‐Vs lower crustal layer is imaged beneath the Proterozoic belt. The strong discontinuity at 20 km may represent the signature of extensional collapse of an orogenic plateau, accommodated by lateral crustal flow. Wide anorthosite massifs inferred to fractionate from a mafic mantle source are abundant in Proterozoic geology and are underlain by high‐Vs lower crust and a gradational Moho. Mafic underplating may have provided a source for these intrusions and could have been an important post‐Archean process stimulating mafic crustal growth in a vertical sense.

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“…Bryan et al 2010;Self et al 2015), in thick packages spread over areas frequently in excess of a 1 × 10 6 km 2 (Self et al 2015), with very short time spans of emplacement (~1 Ma; Bryan et al 2010). They present challenges to understanding the sources of their magmas, temporal and spatial relationship to supercontinents (Svensen et al 2017), continental rifting and possible mantle plumes (Burke and Torsvik 2004;Ernst and Bleeker 2010), magma supply and distribution systems such as dyke and sill complexes, and not least lava flow emplacement and lava pile construction (Walker 1971;Jay et al 2009). The latter is important and raises a number of questions.…”

Section: Introductionmentioning

confidence: 99%

Emplacement of inflated Pāhoehoe flows in the Naude’s Nek Pass, Lesotho remnant, Karoo continental flood basalt province: use of flow-lobe tumuli in understanding flood basalt emplacement

et al. 2018

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Physical volcanological features are presented for a 710-m-thick section, of the Naude's Nek Pass, within the lower part of the Lesotho remnant of the Karoo Large Igneous Province. The section consists of inflated pāhoehoe lava with thin, impersistent sedimentary interbeds towards the base. There are seven discreet packages of compound and hummocky pāhoehoe lobes containing flow-lobe tumuli, making up approximately 50% of the section. Approximately 45% of the sequence consists of 14 sheet lobes, between 10 and 52-m-thick. The majority of the sheet lobes are in two packages indicating prolonged periods of lava supply capable of producing thick sheet lobes. The other sheet lobes are as individual lobes or pairs, within compound flows, suggesting brief increases in lava supply rate. We suggest, contrary to current belief, that there is no evidence that compound flows are proximal to source and sheet lobes (simple flows) are distal to source and we propose that the presence of flow-lobe tumuli in compound flows could be an indicator that a flow is distal to source. We use detailed, previously published, studies of the Thakurvadi Formation (Deccan Traps) as an example. We show that the length of a lobe and therefore the sections that are 'medial or distal to source' are specific to each individual lobe and are dependent on the lava supply of each eruptive event, and as such flow lobe tumuli can be used as an indicator of relative distance from source.

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Cited by 355 publications

References 215 publications

Seismic anisotropy of Precambrian lithosphere: Insights from Rayleigh wave tomography of the eastern Superior Craton

Seismic anisotropy of Precambrian lithosphere: Insights from Rayleigh wave tomography of the eastern Superior Craton

Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions

Emplacement of inflated Pāhoehoe flows in the Naude’s Nek Pass, Lesotho remnant, Karoo continental flood basalt province: use of flow-lobe tumuli in understanding flood basalt emplacement

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