Geologic and geochemical relationships between the contact sublayer, inclusions, and the main mass of the Sudbury Igneous Complex; a case study of the Whistle Mine Embayment

Lightfoot, Peter C.; Keays, Reid R.; Morrison, Gordon G.; Bite, Andy; Farrell, Keith P.

doi:10.2113/gsecongeo.92.6.647

Cited by 68 publications

(58 citation statements)

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“…The REE data for the quartz diorite, disseminated sulphides in Sudbury Breccia, and biotite-hornblende tonalite indicate derivation from bulk SIC melt, as has been suggested for the Offset Dyke quartz diorites elsewhere in the Sudbury Structure (Grant and Bite, 1984), and are not differentiates of the felsic norite phase of the SIC, as has been suggested for quartz diorite dykes in previous studies (Lightfoot et al, 1997;Wood and Spray, 1998). The emplacement of these lithologies into the SRBB must have occurred when the SRBB was still unconsolidated and therefore capable of being injected with quartz diorite, tonalite, and sulphide magmas.…”

Section: Creighton Muukay Pisjtons Huronansupporting

confidence: 70%

The South Range Breccia Belt of the Sudbury Impact Structure: A possible terrace collapse feature

Scott

Spray

2000

Meteorit & Planetary Scien

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Abstract-The South Range Breccia Belt (SRBB) is an arcuate, 45 km long zone of Sudbury Breccia in the South Range of the 1.85 Ga Sudbury Impact Structure. The belt varies in thickness between tens of meters to hundreds of meters and is composed of a polymict assemblage of Huronian Supergroup (2.49-2.20 Ga), Nipissing Diabase (2.2 Ga), and Proterozoic granitoid breccia fragments ranging in size from a few millimeters to tens of meters. The SRBB matrix is composed of a tine-grained (-100 p m ) assemblage of biotite, quartz, and ilmenite, with trace amounts of plagioclase, zircon, titanite, epidote, pyrite, chalcopyrite, pyrrhotite, and occasionally chlorite. The SRBB hosts the Frood-Stobie, Vermilion, and Kirkwood quartz diorite offset dykes, the former being associated with one of the largest Ni-Cu-PGE sulphide deposits in the world.Optical petrography and whole-rock geochemistry concur with previous studies that have suggested that the matrix of the SRBB is derived from comminution and at least partial fiictional melting of the wall rock We suggest that the SRBB was formed by high strain-rate (>1 m/s), gravity-driven seismogenic slip of the inner ring of the Sudbury Impact Structure during postimpact crustal readjustment (crater modification stage). Failure of the hanging wall may have facilitated the injection of bulk SIC melt into the SRBB, along with the Ni-Cu-PGE sulphides of the Frood-Stobie deposit. Postimpact Penokean (1.9-1.7 Ga) tectonism, particularly northwest-directed shearing along the South Range Shear Zone and associated thrust faulting, could account for the present subvertical orientation of the SRBB, and the apparent lack of a connection at depth with the SIC.

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Section: Creighton Muukay Pisjtons Huronansupporting

confidence: 70%

The South Range Breccia Belt of the Sudbury Impact Structure: A possible terrace collapse feature

Scott

Spray

2000

Meteorit & Planetary Scien

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“…The source of the ultramafic material has therefore been interpreted as crucial to the understanding of the origin and development of the sulphide ores. Recent petrological, geochemical, and isotopic work [Lightfoot et al, 1997;Prevec, 2000;Prevec et al, 2000] has demonstrated that the ultramafic material is consistent with derivation by crystallization from within the SIC and not from an external source.…”

Section: Contact Sublayermentioning

confidence: 83%

“…The contact sublayer has been described in detail by numerous workers [e.g., Pattison, 1979;Lightfoot et al, 1997] and comprises a magmatictextured noritic groundmass, hosting inclusions of sulphide, felsic gneiss, basaltic to gabbroic hornfelses, and coarsegrained biotite-rich igneous-textured ultramafic material, and has elevated water and halogen contents relative to the rest of the SIC [e.g., Farrow et al, 1994;Farrow and Watkinson, 1996].…”

Section: Contact Sublayermentioning

confidence: 99%

“…[6] The basaltic nature of the contact sublayer matrix [e.g., has led to the development of various models for the emplacement of the contact sublayer as a discrete, basaltic component, including a separate mantle-derived basaltic magma , a residue of assimilation-fractional crystallization [Lightfoot et al, 1997], and a country rock melt [Prevec, 2000]. These studies have also demonstrated that the geochemical composition of the contact sublayer could be constituted of a tholeiitic basaltic composition contaminated by between 30% and 70% felsic crust (i.e., average Archaean crust, homogenized by impact).…”

Section: Contact Sublayermentioning

confidence: 99%

“…Although the main mass is relatively homogeneous, it also contains fragments varying from several meters to xenocrystic in size [e.g., Peredery and Naldrett, 1975], which are compositionally similar but texturally distinct to the target rocks. The main mass is underlain by a discontinuous breccia-, inclusion-, and sulphide-enriched layer known as contact sublayer, which may comprise up to 30% inclusions of various compositions [e.g., Lightfoot et al, 1997].…”

Section: Physical Parameters Of the Model: The Sudbury Igneous Complexmentioning

confidence: 99%

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Thermal evolution and interaction between impact melt sheet and footwall: A genetic model for the contact sublayer of the Sudbury Igneous Complex, Canada

Prevec

Cawthorn

2002

J. Geophys. Res.

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[1] The Sudbury Igneous Complex (SIC) and associated Ni-Cu-PGE mineralization has been interpreted in terms of a large meteorite impact event. In this study, the thermal relationship between the large cooling melt sheet and the surrounding country rock is examined in terms of its role in an evolving thermal gradient rather than as a passive receptacle for the melt sheet above. Thermal modeling of this environment is undertaken using physical and thermal constraints appropriate to the SIC and assuming heat dissipation from the 2.5-km-thick superheated melt sheet (!1800°C) by either diffusion with zero convection or by rapid convection within the melt sheet. With zero convection, basal cooling produces a solid base, which lowers conductivity such that the immediate footwall rocks reach 1000°C, producing partial melting that extends 200 m into the footwall. In a rapidly convecting melt sheet the initial footwall chill is remelted and high temperatures maintained within the sheet close to the contact. This results in higher temperatures being attained in the immediate footwall (1100-1200°C), inducing complete melting of proximal footwall and partial melting to depths of 500 m below the melt sheet. Proximal footwall consists of Paleoproterozoic Huronian basalts, granitoids and sediments, exposed in the south range, overlying Archaean gneisses and granitoids. Total and partial melting of this material early in the cooling history of the melt sheet and the subsequent gravitational accommodation of these melts according to density would produce a basalt-dominated basal liquid corresponding to the so-called contact sublayer. The thermal aureole predicted by our models is consistent with that preserved around the north range of the SIC assuming $800 m of thermally induced erosion at the contact.

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Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

Huang

Strati

Mantovani

et al. 2014

Geochem. Geophys. Geosyst.

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The SNO1 detector that is currently under construction in Ontario, Canada, will be a new kilotonscale liquid scintillation detector with the capability of recording geoneutrino events that can be used to constrain the strength of the Earth's radiogenic power, and in turn, to test compositional models of the bulk silicate Earth (BSE). We constructed a detailed 3-D model of the regional crust centered at SNO1 from compiled geological, geophysical, and geochemical information. Crustal cross sections obtained from refraction and reflection seismic surveys were used to characterize the crust and assign uncertainties to its structure. The average Moho depth in the study area is 42.3 6 2.6 km. The upper crust was divided into seven dominant lithologic units on the basis of regional geology. The abundances of U and Th and their uncertainties in each upper crustal lithologic unit were determined from analyses of representative outcrop samples. The average chemical compositions of the middle and lower crust beneath the SNO1 region were determined by coupling local seismic velocity profiles with a global compilation of the chemical compositions of amphibolite and granulite facies rocks. Monte Carlo simulations were used to predict the geoneutrino signal originating from the regional crust at SNO1 and to track asymmetrical uncertainties of U and Th abundances. The total regional crust

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Geologic and geochemical relationships between the contact sublayer, inclusions, and the main mass of the Sudbury Igneous Complex; a case study of the Whistle Mine Embayment

Cited by 68 publications

References 0 publications

The South Range Breccia Belt of the Sudbury Impact Structure: A possible terrace collapse feature

The South Range Breccia Belt of the Sudbury Impact Structure: A possible terrace collapse feature

Thermal evolution and interaction between impact melt sheet and footwall: A genetic model for the contact sublayer of the Sudbury Igneous Complex, Canada

Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

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