Timing constraints on deformation history of the Sudbury Impact Structure

1994 ◽  
Vol 31 (11) ◽  
pp. 1654-1660 ◽  
Author(s):  
Jianjun Wu ◽  
Bernd Milkereit ◽  
David Boerner
Keyword(s):  
Timing Constraints ◽  
Impact Structure ◽  
Relative Timing ◽  
Deformation History ◽  
Initial Shape ◽  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Sudbury Structure ◽  
History Of ◽  
Seismic Images

Herein, we present new high-resolution seismic images of the Sudbury Impact Structure, acquired across the Sudbury Igneous Complex and its environs, which provide evidence for the relative timing of the deformation events that reshaped the initial Sudbury Structure. The seismic images show that the lower unit of the Sudbury basinal fill sediments, the Onwatin argillite, is penetrated by a set of blind, imbricated thrusts, whereas the overlying Chelmsford turbidites are unaffected by faulting. We interpret this observation to mean that the deposition of the Chelmsford sediments postdates the latest major deformation of the Sudbury Structure, suggesting that the uniform paleocurrent trends observed in the Chelmsford turbidites are not related to the initial shape of the Sudbury Structure.

Geoscience impact: a synthesis of studies of the Sudbury Structure

2000 ◽  
Vol 37 (2-3) ◽  
pp. 477-501 ◽  
Author(s):  
D E Boerner ◽  
B Milkereit ◽  
A Davidson
Keyword(s):  
Three Dimensional ◽  
Timing Constraints ◽  
Igneous Complex ◽  
Crustal Rocks ◽  
Sudbury Igneous Complex ◽  
Sudbury Structure ◽  
Genetic Interpretation ◽  
History Of ◽  
Post Impact ◽  
Proper Context

Geophysical probing results are synthesized into a three-dimensional framework necessary for understanding the genesis of the Sudbury Structure, based primarily on seismic reflection results centred on the Sudbury Igneous Complex. Remnants of crustal melting from a catastrophic meteorite impact are superimposed on the juxtaposition of mid-crustal rocks exhumed during the Archean against deformed Paleoproterozoic sedimentary rocks. Sedimentation, metamorphism, deformation, and metasomatic overprints are all part of the post-impact history of Sudbury and tend to dominate the geophysical response of the structure. Pre-impact deformation, although certainly preserved in some aspects of Sudbury geology, is not clearly expressed in the geophysical data, nor are any elements of impact-induced deformation. Geophysical views of the Sudbury Igneous Complex are thus somewhat biased in representing mostly the post-impact, but pre-Grenvillian history of the region, with the exception of igneous events. Establishing the proper context for integrating these geophysical results in the genetic interpretation of the Sudbury Structure depends crucially upon timing constraints.

Origin and formation of Metabreccia in the Parkin Offset Dike, Sudbury impact structure, Canada

2020 ◽  
Vol 57 (11) ◽  
pp. 1324-1336
Author(s):  
D. Anders ◽  
G.R. Osinski ◽  
R.A.F. Grieve ◽  
E.A. Pilles ◽  
A. Pentek ◽  
...  
Keyword(s):  
Genetic Relationship ◽  
Analytical Investigation ◽  
Quartz Diorite ◽  
Impact Structure ◽  
Igneous Complex ◽  
Main Mass ◽  
Sudbury Igneous Complex ◽  
The North ◽  
Sudbury Structure ◽  
Geochemical Analyses

The 1.85 Ga Sudbury impact structure is considered a remnant of a peak-ring or multi-ring basin with an estimated original diameter of 150 to 200 km. The Offset Dikes are radial and concentric dikes around the Sudbury Igneous Complex (SIC) and are composed of the so-called inclusion-rich Quartz Diorite (IQD) and inclusion-poor Quartz Diorite (QD), and in some Offset Dikes, Metabreccia (MTBX). We carried out a detailed field and analytical investigation of MTBX from the Parkin Offset Dike in the North Range of the Sudbury structure. Our observations suggest that MTBX represents impact breccia that originally formed underneath the Main Mass of the SIC and that was subsequently contact-metamorphosed and entrained during the emplacement of the Parkin Offset Dike. The MTBX bears no resemblance to the QD and IQD in which it is hosted, but it does share many similarities with Footwall Breccia (FWBX), suggesting that the two shared a similar initial origin. A genetic relationship between MTBX and FWBX is also supported by whole rock geochemical analyses.

Zircon Microstructures Record Deformation History of Shock- and Tectonically-generated Pseudotachylites: a Case Study from the Vredefort Impact Structure, South Africa

2019 ◽  
Vol 60 (12) ◽  
pp. 2529-2546 ◽  
Author(s):  
E Kovaleva ◽  
M S Huber ◽  
G Habler ◽  
D A Zamyatin
Keyword(s):  
Tectonic Deformation ◽  
Impact Structure ◽  
Deformation Bands ◽  
Deformation History ◽  
Meteorite Impacts ◽  
History Of ◽  
Tectonic Settings ◽  
New Criterion

Abstract High-strain rate deformation can cause in situ melting of rocks, resulting in the formation of dark, micro- to nanocrystalline pseudotachylite veins. On Earth, pseudotachylite veins form during meteorite impacts, large landslides, and earthquakes. Within the Vredefort impact structure, both impact-generated and (pre-impact) tectonically-generated pseudotachylite veins have been described, but are challenging to distinguish. Here, we demonstrate a genetic distinction between two pseudotachylite veins from Vredefort by studying their petrography, degree of recrystallization and deformation, cross-cutting relationships and the deformation microstructures in associated zircon. We conclude that Vein 1 is pre-impact and tectonically-generated, and Vein 2 is impact-generated. In agreement, zircon microstructures in Vein 1 contain planar deformation bands (PDBs), attributed to tectonic deformation, whereas zircon microstructures in Vein 2 reveal microtwin lamellae, indisputable evidence of shock metamorphism. Thus, deformation microstructures in zircon may provide a new criterion for distinguishing the genetic origin of pseudotachylite veins. Zircons that have been removed from their context (i.e., alluvial or detrital zircon, zircon from Lunar breccia) should be interpreted with caution in terms of their deformation history. For example, zircon with PDBs cannot reliably be used as a marker for shock deformation, because this feature has been shown to form in purely tectonic settings.

Vitric Compositions in the Onaping Formation and Their Relationship to the Sudbury Igneous Complex, Sudbury Structure

2002 ◽  
Vol 97 (7) ◽  
pp. 1541-1562 ◽  
Author(s):  
D. E. Ames ◽  
J. P. Golightly ◽  
P. C. Lightfoot ◽  
H. L. Gibson
Keyword(s):  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Sudbury Structure

Variation in plagioclase clouding intensity in Matachewan dykes: evidence for the exhumation history of the northern margin of the Sudbury Igneous Complex

2002 ◽  
Vol 39 (6) ◽  
pp. 933-942 ◽  
Author(s):  
J P Siddorn ◽  
H C Halls
Keyword(s):  
Impact Crater ◽  
Regional Metamorphism ◽  
Thin Sections ◽  
Igneous Complex ◽  
Northern Margin ◽  
Sudbury Igneous Complex ◽  
Gneiss Complex ◽  
History Of ◽  
Archean Basement ◽  
Exhumation History

Early Proterozoic Matachewan mafic dykes that cut the Archean Cartier granite – Levack Gneiss Complex north of the Sudbury Igneous Complex (SIC), Canada, are generally metamorphosed to lower amphibolite facies but exhibit locally unaltered plagioclase. These plagioclase feldspars display a clouding similar to that found in the same swarm in the vicinity of the Kapuskasing uplift, about 200 km to the northwest, where the clouding intensity is due to magnetite exsolution and displays a positive correlation with the depth of dyke emplacement. In the Sudbury area, the clouding intensity, obtained by image analysis of thin sections, increases away from the SIC, opposite to the direction of increasing regional metamorphism in the Archean basement. This suggests that the Levack Gneiss Complex north of the SIC was exhumed prior to the intrusion of 2.47 Ga Matachewan dykes and therefore predates the formation of the SIC and associated impact event. The southward tilting of the crust inferred from the plagioclase-clouding data appears to have involved uplift along the Benny Deformation Zone, but the exact age of this deformation is unknown. It may be associated with the 1.8–1.9 Penokean Orogen, 1.85 Ga Sudbury impact crater, or 2.2–2.4 Ga Blezardian Orogen.

Geophysical evidence for a pre-impact Sudbury dome, southern Superior Province, Canada

2005 ◽  
Vol 42 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Stephen A Prevec ◽  
Duncan R Cowan ◽  
Gordon RJ Cooper
Keyword(s):  
Thermal Regime ◽  
Superior Province ◽  
Geochronological Data ◽  
Subsequent Evolution ◽  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Gneiss Complex ◽  
Sudbury Structure ◽  
Abitibi Subprovince

New filtering of aeromagnetic images of the Sudbury area indicates the existence of a large, elliptical feature that appears to underlie the deformed Sudbury Structure in the region of the exposed Levack Gneiss Complex, such that the two features have long axes which are significantly orthogonal to one another. A north–south-oriented ellipse appears to be crosscut by that of the Sudbury Structure and does not correspond to known local lithological or structural trends. The magnetic images, combined with existing tectonic, petrological, geothermometric and geobarometric, and geochronological data, are used to suggest the existence of a pre-impact crustal dome in the southernmost Abitibi subprovince, probably related to ca. 2450 Ma rifting and magmatism in the area. This is consistent with existing petrological and tectonic evidence from a variety of sources. Although the doming is itself unrelated to the ca. 1850 Ma Sudbury event, it may have affected the thermal regime existing at the time of impact, which would have profound implications for the subsequent evolution of the Sudbury Igneous Complex.

scholarly journals The Pele Offset Dykes, Sudbury impact structure, Canada

2018 ◽  
Vol 55 (3) ◽  
pp. 230-240 ◽  
Author(s):  
Eric A. Pilles ◽  
Gordon R. Osinski ◽  
Richard A.F. Grieve ◽  
Adam B. Coulter ◽  
David Smith ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Optical Microscopy ◽  
Electron Microprobe ◽  
The Other ◽  
Impact Structure ◽  
Igneous Complex ◽  
Impact Melt ◽  
Sudbury Igneous Complex ◽  
Geochemical Analyses ◽  
First Time

The Offset Dykes are impact melt-bearing dykes related to the 1.85 Ga Sudbury impact structure. Currently, the dykes extend radially outward from—or occur concentrically around—the Sudbury Igneous Complex, which is the remnant of a differentiated impact melt sheet and the source of the dykes. The recently identified three Pele Offset Dykes intrude into the Archean rocks north of the Sudbury Igneous Complex. In this study, the Pele dykes are characterized for the first time by a combination of fieldwork, optical microscopy, electron microprobe analyses, and bulk geochemical analyses. The Pele Offset Dykes stand out from the other Offset Dykes at Sudbury in two significant ways: (i) All other known Offset Dykes consist of an inclusion-rich lithology in the center of the dyke and an inclusion-poor lithology along the margins. The Pele dykes, however, are only composed of the inclusion-poor phase. (ii) The Pele dykes—particularly the Central and Eastern dykes—have a more evolved chemical composition relative to the other Offset Dykes. These observations suggest that the Pele dykes were emplaced after the other known Offset Dykes during two injection events: the Western followed by the Central and Eastern Pele dykes.

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