scholarly journals Structure and tectonics of the Manitouwadge greenstone belt and Wawa-Quetico subprovince boundary, Superior Province, northwestern Ontario

1994 ◽  
Author(s):  
V L Peterson ◽  
E Zaleski
Keyword(s):  
Greenstone Belt ◽  
Superior Province ◽  
Northwestern Ontario

Orthoquartzite pebbles in Archean conglomerate, North Spirit Lake, northwestern Ontario

1977 ◽  
Vol 14 (9) ◽  
pp. 1980-1990 ◽  
Author(s):  
J. A. Donaldson ◽  
Richard W. Ojakangas
Keyword(s):  
Greenstone Belt ◽  
Sedimentary Rocks ◽  
Canadian Shield ◽  
Superior Province ◽  
Lake Area ◽  
Definite Evidence ◽  
The North ◽  
Northwestern Ontario ◽  
Form Part ◽  
Quartz Grains

An Archean conglomerate in the North Spirit Lake area of northwestern Ontario contains rare orthoquartzite pebbles. Detailed study of these pebbles shows that mineralogically they are very mature, consisting of as much as 99.8 percent quartz and a heavy mineral suite of zircon, tourmaline, and apatite. Textures are typically bimodal, characterized by rounded sand-sized quartz grains set in a 'matrix-cement' of thoroughly recrystallized finer quartz grains. These orthoquartzite pebbles provide the first definite evidence for local tectonic stability of the Canadian Shield before deposition of the immature sedimentary rocks that form part of an Archean (>2.6 Ga) greenstone belt of the Superior Province.

Age structure and orogenic significance of the Berens River composite batholiths, western Superior Province

1998 ◽  
Vol 35 (10) ◽  
pp. 1089-1109 ◽  
Author(s):  
Fernando Corfu ◽  
Denver Stone
Keyword(s):  
Age Structure ◽  
Greenstone Belt ◽  
Biotite Granite ◽  
Superior Province ◽  
Northwestern Ontario ◽  
Peraluminous Granites ◽  
Granitic Intrusions ◽  
Age Patterns ◽  
Greenstone Belts ◽  
Intrusive Activity

The Berens River area of northwestern Ontario is underlain mainly by Archean felsic plutonic rocks, which enclose minor supracrustal and gneissic enclaves and merge with the greenstone-belt-rich Uchi Subprovince to the south. U-Pb geochronology using zircon and monazite shows that the batholiths evolved mainly between 2750 and 2690 Ma by sequential and essentially continuous intrusive activity into an older substratum composed of 3000-2800 Ma volcanic and tonalitic crust. There is a broad, but not strict, compositional transition from early biotite tonalite and hornblende tonalite, progressing with time towards a greater abundance of hornblende granodiorite to granite, and finally to late biotite granite, rare peraluminous granites, and sanukitoid (dioritic, monzodioritic to granitic) plutons. The tonalite suites were predominantly synvolcanic. The late granitic intrusions postdated volcanism, but were largely synchronous with the main compressional events that caused widespread sedimentation, deformation, and metamorphism in other parts of the region. The age patterns and compositional features of the batholiths and the spatial and temporal links between their evolution and those of the supracrustal sequences in the greenstone belts of the region are consistent with mechanisms of magma generation and emplacement at converging plate margins.

Two hundred and twenty million years of Archean evolution: a zircon U–Pb age stratigraphic study of the Uchi–Confederation Lakes greenstone belt, northwestern Ontario

1980 ◽  
Vol 17 (6) ◽  
pp. 710-721 ◽  
Author(s):  
P. D. Nunes ◽  
P. C. Thurston
Keyword(s):  
Greenstone Belt ◽  
Indirect Evidence ◽  
The Other ◽  
Superior Province ◽  
Time Interval ◽  
Northwestern Ontario ◽  
Quartz Monzonite

Three metavolcanic units in the Uchi–Confederation Lakes greenstone belt have been dated by the zircon U–Pb method. Ages obtained reveal a time interval of [Formula: see text] separating the cycle I crystal tuff (2958.6 ± 1.7 Ma) from the cycle III rhyolite ([Formula: see text]). A cycle II rhyolite about 2794 Ma old lies between the other two units. Uranium-rich xenocrystic cores occur in the cycle I zircons and are indirect evidence of preexisting sialic material.A metamorphosed granodiorite, intrusive into the cycle III rhyolite, is about the same age as the rhyolite. A post-metamorphic quartz monzonite pluton is dated at 2729.6 ± 1.3 Ma. A period of dynamothermal metamorphism in this portion of the Superior Province indirectly dated at [Formula: see text] reflects the Kenoran orogeny.

Rubidium–strontium ages from the Oxford Lake – Knee Lake greenstone belt, northern Manitoba

1980 ◽  
Vol 17 (5) ◽  
pp. 560-568 ◽  
Author(s):  
G. S. Clark ◽  
S.-P. Cheung
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Superior Province ◽  
Granitic Intrusion ◽  
Greenstone Belts ◽  
Archean Greenstone Belts

Rb–Sr whole-rock ages have been determined for rocks from the Oxford Lake – Knee Lake – Gods Lake greenstone belt, in the Superior Province of northeastern Manitoba.The age of the Magill Lake Pluton is 2455 ± 35 Ma (λ87Rb = 1.42 × 10−11 yr−1), with an initial 87Sr/86Sr ratio of 0.7078 ± 0.0043. This granitic stock intrudes the Oxford Lake Group, so it is post-tectonic and probably related to the second, weaker stage of metamorphism.The age of the Bayly Lake Pluton is 2424 ± 74 Ma, with an initial 87Sr/86Sr ratio of 0.7029 ± 0.0001. This granodioritic batholith complex does not intrude the Oxford Lake Group. It is syn-tectonic and metamorphosed.The age of volcanic rocks of the Hayes River Group, from Goose Lake (30 km south of Gods Lake Narrows), is 2680 ± 125 Ma, with an initial 87Sr/86Sr ratio of 0.7014 ± 0.0009.The age for the Magill Lake and Bayly Lake Plutons can be interpreted as the minimum ages of granitic intrusion in the area.The age for the Hayes River Group volcanic rocks is consistent with Rb–Sr ages of volcanic rocks from other Archean greenstone belts within the northwestern Superior Province.

Overview of regional geophysical studies in Manitoba and northwestern Ontario

1982 ◽  
Vol 19 (11) ◽  
pp. 2049-2059 ◽  
Author(s):  
D. H. Hall ◽  
W. C. Brisbin
Keyword(s):  
Greenstone Belt ◽  
Seismic Velocities ◽  
Crustal Layer ◽  
Northwestern Ontario ◽  
Reflection And Refraction ◽  
Gravity And Magnetic ◽  
Winnipeg River ◽  
Lower Crustal ◽  
Gravity And Magnetic Anomaly

This paper presents an overview of six geophysical projects (seismic reflection and refraction, gravity and magnetic anomaly interpretation, specific gravity and magnetic property measurements) carried out in an area in Manitoba and northwestern Ontario bounded by 93 and 96°W longitude, and 49 and 51°N latitude.The purpose of the surveys was to define crustal structure in the Kenora–Wabigoon greenstone belt, the Winnipeg River batholithic belt, the Ear Falls – Manigotagan gneiss belt, and the Uchi greenstone belt. The following conclusions emerge.In all of the belts, a major discontinuity divides the crust into the commonly found upper and lower crustal sections. At the top of the lower crust, a seismically distinct layer (the mid-crustal layer) occurs. Seismic velocities in this layer suggest either intermediate to basic igneous rocks or metamorphic rocks of the amphibolite facies.Crustal geophysical characteristics vary sufficiently among the four belts to justify the classification of all four as distinct subprovinces of the Superior Province.Cet article présente une vue générale sur six projets de géophysique (réflexion et réfraction sismique, interprétation d'anomalies de gravité et magnétiques, déterminations de densité et de propriétés magnétiques) réalisés dans une région du Manitoba et du nord-ouest de l'Ontario encadrée par les longitudes 93 et 96°O et les latitudes 49 et 51°N.

scholarly journals Geology, Red Lake greenstone belt, western Superior Province, Ontario

2004 ◽  
Author(s):  
M Sanborn-Barrie ◽  
T Skulski ◽  
J Parker
Keyword(s):  
Greenstone Belt ◽  
Superior Province ◽  
Red Lake

scholarly journals Geology, Sturgeon Lake greenstone belt, western Superior Province, Ontario

2005 ◽  
Author(s):  
M Sanborn-Barrie ◽  
T Skulski
Keyword(s):  
Greenstone Belt ◽  
Superior Province
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