Sudbury Breccia (Canada): a product of the 1850 Ma Sudbury Event and host to footwall Cu–Ni–PGE deposits

Rousell, D. H.; Fedorowich, John S.; Dressler, B. O.

doi:10.1016/s0012-8252(02)00091-0

Cited by 58 publications

(30 citation statements)

References 36 publications

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“…Lithic fragments in these bodies may be up to many meters in diameter, are generally well-rounded, elliptical in plan view, and chiefly derived from adjacent lithological units (Dressler 1984a). The matrix of pseudotachylite veins and clast-rich pseudotachylite bodies is fine-grained to aphanitic and often shows evidence for ductile flow during brecciation (Rousell et al 2003;Legault et al 2003). Collectively, this points to in situ formation of these impactites due to the passage of a shock wave (cf.…”

Section: Major Structural and Lithological Characteristics Of The Sudmentioning

confidence: 99%

Structural characteristics of the Sudbury impact structure, Canada: Impact-induced versus orogenic deformation-A review

Riller

2005

Meteoritics &Amp; Planetary Science

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Abstract-Orogenic deformation, both preceding and following the impact event at Sudbury, strongly hinders a straightforward assessment of impact-induced geological processes that generated the Sudbury impact structure. Central to understanding these processes is the state of strain of the Sudbury Igneous Complex, the solidified impact melt sheet, its underlying target rocks, overlying impact breccias and post-impact sedimentary rocks. This review addresses (1) major structural, metamorphic and magmatic characteristics of the impact melt sheet and associated dikes, (2) attempts that have been made to constrain the primary geometry of the igneous complex, (3) modes of impactinduced deformation as well as (4) mechanisms of pre-and post-impact orogenic deformation. The latter have important consequences for estimating parameters such as magnitude of structural uplift, tilting of pre-impact (Huronian) strata and displacement on major discontinuities which, collectively,have not yet been considered in impact models. In this regard, a mechanism for the emplacement of Offset Dikes is suggested, that accounts for the geometry of the dikes and magmatic characteristics, as well as the occurrence of sulfides in the dikes. Moreover, re-interpretation of published paleomagnetic data suggests that orogenic folding of the solidified melt sheet commenced shortly after the impact. Uncertainties still exist as to whether the Sudbury impact structure was a peak-ring or a multi-ring basin and the deformation mechanisms of rock flow during transient cavity formation and crater modification.

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Section: Major Structural and Lithological Characteristics Of The Sudmentioning

confidence: 99%

Structural characteristics of the Sudbury impact structure, Canada: Impact-induced versus orogenic deformation-A review

Riller

2005

Meteoritics &Amp; Planetary Science

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“…Pseudotachylyte at Sudbury occurs in a number of different forms and settings (Dressler 1984;Rousell et al 2003). It has been suggested that pseudotachylytes in impact structures are generated by two main processes (Spray 1998b): 1) shock wave-rock interaction with the formation of the so called S-(shock) type pseudotachylyte, and 2) tectonic activity (e.g., gravity driven faulting, wrench faulting, thrust faulting) with the formation of the so called E-(endogenic) type pseudotachylyte.…”

Section: Pseudotachylyte (Sudbury Breccia)mentioning

confidence: 99%

Tectonic influences on the morphometry of the Sudbury impact structure: Implications for terrestrial cratering and modeling

Spray

Butler²,

Thompson

2004

Meteorit & Planetary Scien

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Abstract-Impact structures developed on active terrestrial planets (Earth and Venus) are susceptible to pre-impact tectonic influences on their formation. This means that we cannot expect them to conform to ideal cratering models, which are commonly based on the response of a homogeneous target devoid of pre-existing flaws. In the case of the 1.85 Ga Sudbury impact structure of Ontario, Canada, considerable influence has been exerted on modification stage processes by late Archean to early Proterozoic basement faults. Two trends are dominant: 1) the NNW-striking Onaping Fault System, which is parallel to the 2.47 Ga Matachewan dyke swarm, and 2) the ENE-striking Murray Fault System, which acted as a major Paleoproterozoic suture zone that contributed to the development of the Huronian sedimentary basin between 2.45-2.2 Ga. Sudbury has also been affected by syn-to post-impact regional deformation and metamorphism: the 1.9-1.8 Ga Penokean orogeny, which involved NNW-directed reverse faulting, uplift, and transpression at mainly greenschist facies grade, and the 1.16-0.99 Ga Grenville orogeny, which overprinted the SE sector of the impact structure to yield a polydeformed upper amphibolite facies terrain. The pre-, syn-, and post-impact tectonics of the region have rendered the Sudbury structure a complicated feature. Careful reconstruction is required before its original morphometry can be established. This is likely to be true for many impact structures developed on active terrestrial planets.Based on extensive field work, combined with remote sensing and geophysical data, four ring systems have been identified at Sudbury. The inner three rings broadly correlate with pseudotachylyte (friction melt) -rich fault systems. The first ring has a diameter of ~90 km and defines what is interpreted to be the remains of the central uplift. The second ring delimits the collapsed transient cavity diameter at ~130 km and broadly corresponds to the original melt sheet diameter. The third ring has a diameter of ~180 km. The fourth ring defines the suggested apparent crater diameter at ~260 km. This approximates the final rim diameter, given that erosion in the North Range is <6 km and the ring faults are steeply dipping. Impact damage beyond Ring 4 may occur, but has not yet been identified in the field. One or more rings within the central uplift (Ring 1) may also exist. This form and concentric structure indicates that Sudbury is a peak ring or, more probably, a multi-ring basin. These parameters provide the foundation for modeling the formation of this relatively large terrestrial impact structure.

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“…In Sudbury, the term 'Sudbury Breccia' has been used to describe a variety of breccia types that may have different origins (e.g., Dressler, 1984;Mü ller-Mohr, 1992). These melt breccias are generally characterized by rounded wall rock fragments set in a dark, aphanitic to microcrystalline matrix (Shand, 1916;Rousell et al, 2003;Dressler and Reimold, 2004). The term "pseudotachylyte" was coined first by Shand (1916) who described the widespread occurrences of this lithology in the Vredefort Dome of South Africa.…”

Section: Introductionmentioning

confidence: 99%

“…This pseudotachylite melt origin is essentially based on the compositional similarity between pseudotachylite matrix and adjacent wall rock, unless melt relocation within target rock is invoked (Dressler and Reimold, 2004;Gibson and Reimold, 2005;Melosh, 2005). Indeed, many geochemical studies report that compositions of pseudotachylite matrix and adjacent wall rock are largely similar, although distinct differences between the two have been noted as well (e.g., Speers, 1957;Dressler, 1984;Reimold, 1991;Rousell et al, 2003). Compositional similarity between matrix and wall rock as seen in whole-rock analyses may, however, be of limited significance if the matrix contains a high content of small wall rock fragments.…”

Section: Introductionmentioning

confidence: 99%

Petrographic and geochemical evidence for an allochthonous, possibly impact melt, origin of pseudotachylite from the Vredefort Dome, South Africa

Lieger

Riller

Gibson

2011

Geochimica et Cosmochimica Acta

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Sudbury Breccia (Canada): a product of the 1850 Ma Sudbury Event and host to footwall Cu–Ni–PGE deposits

Cited by 58 publications

References 36 publications

Structural characteristics of the Sudbury impact structure, Canada: Impact-induced versus orogenic deformation-A review

Structural characteristics of the Sudbury impact structure, Canada: Impact-induced versus orogenic deformation-A review

Tectonic influences on the morphometry of the Sudbury impact structure: Implications for terrestrial cratering and modeling

Petrographic and geochemical evidence for an allochthonous, possibly impact melt, origin of pseudotachylite from the Vredefort Dome, South Africa

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