Sudbury Breccia distribution and orientation in an embayment environment

Fedorowich, John S.; Rousell, D. H.; Peredery, Walter V.

doi:10.1130/0-8137-2339-6.305

Cited by 10 publications

(8 citation statements)

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“…This Cu-rich sulfide liquid then settled into zones of brecciated gneissic rock (Sudbury Breccia) in the footwall to the SIC (i.e., Li 1992, Li & Naldrett 1993. The zones of Sudbury Breccia that host footwall-style Cu-Ni-PGE mineralization occur below the Strathcona embayment, subparallel to the embayment axis, which plunges ap-proximately 21° SSW (Fedorowich et al 1999) (Fig. 1b).…”

Section: Geological Setting and Location Of Studymentioning

confidence: 99%

“…The matrix encloses angular to rounded clasts of local host-rocks. The greatest volumes of Sudbury Breccia are found surrounding and along the surfaces of the structurally complex depressions of the footwall contact beneath the SIC known as embayments, hosting the sulfide mineralization described above (Cowan 1968, Fedorowich et al 1999.…”

Section: Characteristics Of the Sudbury (Levack) Brecciamentioning

confidence: 99%

“…Samples collected from each of the study areas were classified according to their proximity to known foot- Fig. 2c), whereas the adjacent hanging-wall of this Sudbury Breccia zone is weakly brecciated and contains less than 18 vol.% matrix and clasts (Fedorowich et al 1999). The limits of this breccia zone to the east of the haulage drift between Zones 38 and 37 and in the hanging wall of Zone 38 are unknown owing to limited data derived from drilling in that area.…”

Section: Sampling and Classification Of Samples Of Sudbury Breccia Mamentioning

confidence: 99%

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CHLORINE ENRICHMENT AND HYDROUS ALTERATION OF THE SUDBURY BRECCIA HOSTING FOOTWALL Cu Ni PGE MINERALIZATION AT THE FRASER MINE, SUDBURY, ONTARIO, CANADA

Hanley

Mungall

2003

The Canadian Mineralogist

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An assemblage of hydrous, Cl-bearing alteration-induced minerals is present within 150 m of footwall-style Cu-Ni-PGE sulfide mineralization hosted by the Sudbury Breccia at the Fraser Copper zone, Fraser mine, Onaping-Levack area, Ontario. The pyroxene hornfels to hornblende hornfels contact-metamorphic aureole of the Sudbury Igneous Complex (SIC) contains less than 15 modal % hydroxysilicates. Near the mineralized areas, a diagnostic assemblage of secondary minerals of the albite-epidote hornfels facies is present in the matrix of the Sudbury Breccia; it contains 25 to 80% actinolite + chamosite as well as epidote + sodic plagioclase (An 2.8-42 ) + quartz ± titaniferous magnetite ± biotite ± K-feldspar ± titanite. The Cl content and Cl/(Cl + F) values of amphibole and biotite in this matrix are elevated within 150 m of mineralization, and increase toward known occurrences of sulfides. Parameters of K, Na, and A-site occupancy correlate with Cl content in actinolite in such matrix material. The value of Mg# is lower in biotite in the matrix near mineralized areas and is inversely correlated with Cl/(Cl + F) in the biotite, reflecting Mg-Cl or Fe-F avoidance. Calculated temperatures of amphibole-plagioclase equilibration for the diagnostic hydrous assemblage are between 442 to 540 ± 75°C. The assemblage formed during a retrograde metamorphic event during or after footwall Cu-Ni-PGE mineralization, and after passage of peak conditions of contact metamorphism at the base of the SIC. The enrichment of Cl in this assemblage was the result of the increased amounts of free Cl relative to F in the equilibrating fluid, and favorable cation proportions for incorporation of Cl into the structure of hydroxysilicate minerals. The Cl-bearing assemblage accounts for a significant portion of the bulk halogen content of Sudbury Breccia matrix. It is unique to zones of Sudbury Breccia that host mineralization, and hence may be used to identify prospective areas. SOMMAIRENous décrivons un assemblage de minéraux d'altération hydratés et contenant du chlore dans une auréole de 150 m autour des indices minéralisés (Cu-Ni-EGP, sulfures) dans le socle bréchifié sous le complexe igné de Sudbury, à la zone dite de Fraser Copper, exploitée à la mine Fraser, région de Onaping-Levack, en Ontario. Les hornfels à pyroxène et à hornblende de l'auréole de contact autour de ce complexe contiennent moins de 15% de ces silicates hydroxylés. Près des indices imnéralisés, en revanche, nous trouvons un assemblage distinctif de minéraux secondaires équilibrés dans le faciès des hornfels à albite-épidote, développés dans la matrice de la Brèche de Sudbury; sont présents de 25 à 80% d'un assemblage à actinolite + chamosite, de même que épidote + plagioclase sodique (An 2.8-42 ) + quartz ± magnétite titanifère ± biotite ± feldspath potassique ± titanite. La teneur en Cl et les valeurs du rapport Cl/(Cl + F) de l'amphibole et de la biotite dans cette matrice sont élevées à l'intérieur de cette auréole de 150 m autour des zones minéralisées, et augmentent d...

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Section: Geological Setting and Location Of Studymentioning

confidence: 99%

Section: Characteristics Of the Sudbury (Levack) Brecciamentioning

confidence: 99%

Section: Sampling and Classification Of Samples Of Sudbury Breccia Mamentioning

confidence: 99%

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CHLORINE ENRICHMENT AND HYDROUS ALTERATION OF THE SUDBURY BRECCIA HOSTING FOOTWALL Cu Ni PGE MINERALIZATION AT THE FRASER MINE, SUDBURY, ONTARIO, CANADA

Hanley

Mungall

2003

The Canadian Mineralogist

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“…The impact struck metasedimentary rocks of the Huronian Supergroup, including quartzites, shales, and also carbonates, in addition to the Archean crystalline basement (e.g., Fedorowich et al. ), locally intruded by granitic plutons and the East Bull Lake suite, which also included noritic dikes and layered mafic intrusions (e.g., Vogel et al. ).…”

Section: Introductionmentioning

confidence: 99%

“…The SIC is cut by a complex series of large-scale faults that are related to both original emplacement and later deformation, and include the economically important offset dikes. The impact struck metasedimentary rocks of the Huronian Supergroup, including quartzites, shales, and also carbonates, in addition to the Archean crystalline basement (e.g., Fedorowich et al 1999), locally intruded by granitic plutons and the East Bull Lake suite, which also included noritic dikes and layered mafic intrusions (e.g., Vogel et al 1998).…”

Section: Introduction Sudbury Structurementioning

confidence: 99%

Petrography and geochemistry of ejecta from the Sudbury impact event

Huber

McDonald

Koeberl

2014

Meteorit & Planetary Scien

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Ejecta from the Connors Creek site in Michigan (500 km from the Sudbury Igneous Complex [SIC]), the Pine River site in western Ontario (650 km from the SIC), and the Coleraine site in Minnesota (980 km from the SIC) were petrographically and geochemically analyzed. Connors Creek was found to have approximately 2 m of ejecta, including shocked quartz, melt droplets, and accretionary lapilli; Pine River has similar deposits about 1 m in thickness, although with smaller lapilli; Coleraine contains only impact spherules in a 20 cm‐thick layer (impact spherules being similar to microkrystites or microtektites). The ejecta transition from chaotic deposits of massively bedded impactoclastic material with locally derived detritus at Connors Creek to a deposit with apparently very little detrital material that is primarily composed of melt droplets at Pine River to a deposit that is almost entirely composed of melt spherules at Coleraine. The major and trace element compositions of the ejecta confirm the previously observed similarity of the ejecta deposits to the Onaping Formation in the SIC. Platinum‐group element (PGE) concentrations from each of the sites were also measured, revealing significantly elevated PGE contents in the spherule samples compared with background values. PGE abundances in samples from the Pine River site can be reproduced by addition of approximately 0.2 wt% CI chondrite to the background composition of the underlying sediments in the core. PGE interelement ratios indicate that the Sudbury impact event was probably caused by a chondritic impactor.

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2017

Nickel Sulfide Ores and Impact Melts

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Sudbury Breccia distribution and orientation in an embayment environment

Cited by 10 publications

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CHLORINE ENRICHMENT AND HYDROUS ALTERATION OF THE SUDBURY BRECCIA HOSTING FOOTWALL Cu Ni PGE MINERALIZATION AT THE FRASER MINE, SUDBURY, ONTARIO, CANADA

CHLORINE ENRICHMENT AND HYDROUS ALTERATION OF THE SUDBURY BRECCIA HOSTING FOOTWALL Cu Ni PGE MINERALIZATION AT THE FRASER MINE, SUDBURY, ONTARIO, CANADA

Petrography and geochemistry of ejecta from the Sudbury impact event

References and Sudbury Bibliography

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