Occurrences of pseudotachylyte at the East Bull Lake and Shakespeare–Dunlop intrusions, Ontario, Canada

1994 ◽  
Vol 31 (12) ◽  
pp. 1744-1748 ◽  
Author(s):  
P. T. Chubb ◽  
D. C. Vogel ◽  
D. C. Peck ◽  
R. S. James ◽  
R. R. Keays
Keyword(s):  
Radial Distance ◽  
Western Margin ◽  
Igneous Complex ◽  
Fine Grained ◽  
Rock Fragments ◽  
Sudbury Igneous Complex ◽  
The North ◽  
Granitoid Rocks ◽  
Frictional Melting ◽  
Crystalline Matrix

Pseudotachylyte bodies were recently identified within and adjacent to the Early Proterozoic East Bull Lake and Shakespeare–Dunlop intrusions, located approximately 25–40 km west-southwest of the western margin of the Sudbury Igneous Complex. These breccia-like bodies locally form extensive vein networks and are preferentially developed along the contact between the intrusions and older Archean granitoid rocks. The pseudotachylyte veins comprise variable proportions of locally derived rock fragments and an aphanitic to fine-grained crystalline matrix that commonly displays flow textures. The veins appear to have formed by intense cataclasis and (or) frictional melting. These occurrences are very similar in appearance to Sudbury Breccia dykes that are observed at a radial distance of up to 80 km from the Sudbury Igneous Complex. Sudbury Breccia is widely believed to have formed as a result of the Sudbury event—a cataclysmic explosion that occurred at 1.85 Ga. The location of the pseudotachylyte veins described herein may coincide with one of the concentric bands of relatively intense Sudbury Breccia development observed to the north of the Sudbury Igneous Complex.

scholarly journals The Basal Onaping Intrusion in the North Range: Roof rocks of the Sudbury Igneous Complex

2015 ◽  
Vol 50 (9) ◽  
pp. 1577-1594 ◽  
Author(s):  
Denise Anders ◽  
Gordon R. Osinski ◽  
Richard A. F. Grieve ◽  
Derek T. M. Brillinger
Keyword(s):  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
The North ◽  
Roof Rocks

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.

New U–Pb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 619-637 ◽  
Author(s):  
R M Friedman ◽  
L J Diakow ◽  
R A Lane ◽  
J K Mortensen
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Western Margin ◽  
Fine Grained ◽  
The North ◽  
Continental Arc ◽  
Igneous Activity ◽  
Minimum Age ◽  
Plateau Central ◽  
Cretaceous Magmatism

New U–Pb ages and K–Ar dates, primarily for rocks proximal to mineral occurrences in the Fawnie Range of central British Columbia, document latest Cretaceous (ca. 74–66 Ma) continental-arc igneous activity and date associated base and precious metal mineralization. U–Pb ages of ca. 73–69 Ma for the Capoose pluton and hypabyssal to extrusive garnet rhyolites at the Capoose prospect demonstrate a latest Cretaceous age for mineralization and a likely plutonic source for mineralizing fluids. A U–Pb age of ca. 67 Ma for a late mineralized felsic dyke and two K–Ar dates (ca. 70 and 68 Ma) for hornfelsed Jurassic volcanic rocks at the Blackwater–Davidson prospect constrain a latest Cretaceous age for mineralization. A U–Pb age of ca. 74 Ma for a fine grained diorite sill that cuts a significant epithermal gold vein at the Tsacha prospect places a minimum age on mineralization at this probable Jura-Cretaceous deposit and documents latest Cretaceous magmatism. Latest Cretaceous K–Ar dates are reported for an andesite flow adjacent to the Eocene Holy Cross deposit (ca. 66 Ma), about 35 km north of the Fawnie Range, and a Kasalka Group rhyolite (ca. 68 Ma) exposed near the western margin of the Nechako Plateau. Latest Cretaceous magmatism and mineralization in the Fawnie Range represent the waning stages of Bulkley suite magmatism and porphyry-style mineralization, which was concentrated along the western margin of the Nechako Plateau at circa 88–70 Ma. The distribution of latest Cretaceous arc igneous rocks along the North American Cordilleran is reviewed and tectonic implications discussed.

Petrology and Sedimentation of Huronian Arenites, South of Espanola, Ontario

1971 ◽  
Vol 8 (1) ◽  
pp. 20-49 ◽  
Author(s):  
S. M. Casshyap
Keyword(s):  
Depositional Environment ◽  
Source Rocks ◽  
Coarse Grained ◽  
Integrated Analysis ◽  
Rock Fragments ◽  
The North ◽  
Potassic Feldspar ◽  
Lithostratigraphic Units ◽  
Near Shore ◽  
Granitoid Rocks

The five arenaceous lithostratigraphic units of the Huronian sequence recognized in the Espanola–Willisville area are the Mississagi, Espanola, Serpent, and the Lorrain Formation, as also the intercalated zone which forms the uppermost subdivision of the Gowganda Formation.The bulk of the Huronian arenites is a mixed assemblage of fine, medium, and coarse subarkose, and arkose which are either poorly sorted, muddy fine-to-medium grained (Mississagi, calcareous Espanola, lower Serpent) and muddy medium-to-coarse grained (lower and middle Lorrain), or, moderately well-sorted, medium-to-coarse grained (middle and upper Serpent and intercalated zone). There is, however, one unit in the upper part of the Huronian sequence (uppermost Lorrain) which is a brilliant white supermature quartzarenite. Among the notable petrographic features are a lower quartz – feldspar ratio, rock fragments of metasedimentary and metavolcanic origin, and occasionally occurring rounded quartz. The feldspathic debris for these arenites was derived largely from the older granitoid rocks similar to the 'Algoman granite' of the Canadian Shield to the north of the study area and partly from the supracrustal rocks infolded in the granitoid terrain. Dominance of plagioclase (oligoclase ?) over potassic feldspar and their overall freshness in the arenites may suggest that the source rocks by and large were not deeply weathered,An integrated analysis of lithologie association and sedimentary characters, including texture and mineralogy of the arenites, possibly indicates a near-shore depositional environment (? fluviatile-deltaic) for several Huronian arenites (Mississagi, Serpent, intercalated zone, and middle and upper Lorrain); some may be deltaic-marine (lower part of lower Lorrain). Calcareous Espanola was perhaps deposited beyond the shoreline partly in deeper waters and partly in shallow turbulent environment. Likewise, clean white quartzarenite of top Lorrain may represent deposition in the turbulent fore-shore zone (beach or shelf).

scholarly journals Geochemistry and Petrogenesis of Mafic and Ultramafic Inclusions in Sublayer and Offset Dikes, Sudbury Igneous Complex, Canada

2020 ◽  
Vol 61 (6) ◽  
Author(s):  
Yujian Wang ◽  
C Michael Lesher ◽  
Peter C Lightfoot ◽  
Edward F Pattison ◽  
J Paul Golightly
Keyword(s):  
Matrix Group ◽  
Igneous Complex ◽  
Middle Crust ◽  
Group Iii ◽  
Impact Melt ◽  
Sudbury Igneous Complex ◽  
The North ◽  
Group I ◽  
Group Ii ◽  
The Impact

Abstract The c. 1·85 Ga Sudbury Igneous Complex (SIC) is the igneous remnant of one of the oldest, largest and best-preserved impact structures on Earth and contains some of the world’s largest magmatic Ni–Cu–PGE sulfide deposits. Most of the mineralization occurs in Sublayer, Footwall Breccia and inclusion-bearing quartz diorite (IQD), all of which contain significant (Sublayer and IQD) to minor (Footwall Breccia) amounts of olivine-bearing mafic–ultramafic inclusions. These inclusions have only rare equivalents in the country rocks and are closely associated with the Ni–Cu–PGE sulfide mineralization. They can be divided into three groups on the basis of petrography and geochemical characteristics. Group I (n = 47) includes igneous-textured olivine melanorite and olivine melagabbronorite inclusions in the Whistle and Levack embayments on the North Range with Zr/Y, Zr/Nb, Nb/U and Zr/Hf similar to igneous-textured Sublayer matrix. Group I inclusions are interpreted to be anteliths that crystallized from a mixture of SIC impact melt and a more mafic melt, probably derived by melting of ultramafic footwall rocks. Group II includes Group IIA (n = 17) shock metamorphosed wehrlite and olivine clinopyroxenite inclusions in the Levack embayment and Group IIB (n = 2) shock metamorphosed olivine melanorite inclusions in the Foy Offset on the North Range. Group II inclusions have similar trace element patterns [e.g. negative Th–U, Nb–Ta–(Ti), Sr and Zr–Hf anomalies] and overlapping Nb/U to a layered mafic–ultramafic intrusion in the footwall of the Levack and Fraser deposits, which together with their limited distribution suggests that Group II inclusions are locally-derived xenoliths. Group III (n = 21) includes phlogopite lherzolite and feldspar lherzolite inclusions with igneous, recrystallized and shock-metamorphic textures in the Trill, Levack and Bowell embayments, and the Foy Offset dike on the North Range. They have no equivalents in the exposed country rocks. The calculated parental magma is similar to continental arc basalt formed by approximately 5% partial melting of garnet peridotite. Ol–Cpx–Pl thermobarometry of several Group III inclusions indicate equilibration at 900–1120 ºC and 210 ± 166 MPa to 300 ± 178 MPa, suggesting crystallization in the upper-middle crust (7·7 ± 6·6 to 10·9 ± 6·5 km), prior to being incorporated into the lower parts of the impact melt sheet during impact excavation. The exotic xenoliths provide information about the depth of impact and composition of upper-middle crust in the Sudbury region at 1850 Ma, the local xenoliths provide information about the thermomechanical erosion process that followed generation of the impact melt, the anteliths provide information about the early crystallization history of the SIC, and all of the inclusions provide constraints on the genesis of Sublayer, IQD, footwall breccia, and associated Ni–Cu–PGE mineralization.

Surficial geochemical and mineralogical signatures of Ni-Cu-PGE deposits in glaciated terrain: examples from the South Range of the Sudbury Igneous Complex, Ontario, Canada

2021 ◽  
pp. 104301
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Daniel Layton-Matthews ◽  
Stewart Hamilton ◽  
M. Beth McClenaghan ◽  
...  
Keyword(s):  
The South ◽  
Igneous Complex ◽  
Sudbury Igneous Complex

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

Sign in / Sign up

Export Citation Format

Share Document