New Insights into Archean Crustal Development from Geochronology in the Rainy Lake Area, Superior Province, Canada

1989 ◽  
Vol 97 (4) ◽  
pp. 379-398 ◽  
Author(s):  
D. W. Davis ◽  
K. H. Poulsen ◽  
S. L. Kamo
Keyword(s):  
Superior Province ◽  
Lake Area

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.

Relative age of Otto stock and Matachewan dykes from paleomagnetism and implications for the Precambrian polar wander path

1990 ◽  
Vol 27 (7) ◽  
pp. 915-922 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Douglas J. Neilson ◽  
Christopher J. Hale
Keyword(s):  
North America ◽  
Superior Province ◽  
Contact Aureole ◽  
Lake Area ◽  
Polar Wander ◽  
Relative Age ◽  
Contact Test ◽  
Magnetic Remanence

North-trending diabase dykes within and near the Otto syenite stock of the Kirkland Lake area of the Superior Province carry a stable paleomagnetic remanence identical to that of 2454 ± 2 Ma Matachewan dykes far from the stock. A positive baked contact test for the remanence of a dyke within the stock demonstrates that the remanence is primary. Thus, (1) these dykes belong to the Matachewan swarm, (2) the Otto stock has not magnetically overprinted Matachewan dykes in its contact aureole as previously reported, and (3) the stock must be older than 2454 Ma.The magnetic remanence associated with the Otto stock, previously thought to be primary, must now be considered of uncertain age. Nevertheless, the positive baked contact test for the remanence of the Matachewan dyke within the stock demonstrates that the remanence associated with the stock predates intrusion of the Matachewan swarm.The conventional polar wander path for Precambrian North America decreases in age from the Matachewan paleopole to the Otto stock paleopole. Since this study demonstrates that the Otto stock pole is older than the Matachewan pole, there is a serious problem with the conventional path.

Trace-element geochemistry of ore-associated and barren, felsic metavolcanic rocks in the Superior Province, Canada

1986 ◽  
Vol 23 (2) ◽  
pp. 222-237 ◽  
Author(s):  
C. M. Lesher ◽  
A. M. Goodwin ◽  
I. H. Campbell ◽  
M. P. Gorton
Keyword(s):  
Base Metal ◽  
Superior Province ◽  
Lake Area ◽  
Magma Chambers ◽  
Base Metal Sulphide ◽  
Metal Sulphide ◽  
Metavolcanic Rocks ◽  
Sulphide Deposits ◽  
High Level ◽  
Ree Patterns

Archaean felsic metavolcanic rocks in the Superior Province of the Canadian Shield may be divided into three major groups on the basis of trace-element abundances and ratios. (1) FI felsic metavolcanic rocks are dacites and rhyodacites characterized by steep REE patterns with weakly negative to moderately positive Eu anomalies, high Zr/Y, low abundances of high-field-strength elements (e.g., HREE, Y, Zr, Hf), and high abundances of Sr. Examples occur in the Bowman Subgroup and Skead Group in the Abitibi Belt, in the Kakagi Lake, Lake of the Woods, Shoal Lake, and Sturgeon Lake areas of the Wabigoon Belt, and in the Confederation Lake area of the Uchi Belt. None of these horizons, as known, hosts base-metal sulphide deposits. (2) FII felsic metavolcanic rocks are rhyodacites and rhyolites characterized by gently sloping REE patterns with variable Eu anomalies, moderate Zr/Y, and intermediate abundances of HFS elements and Sr. Examples occur in the Misema Subgroup of the Abitibi Belt, in the Wabigoon Lake and Sturgeon Lake areas of the Wabigoon Belt, and in the Confederation Lake area of the Uchi Belt. Of these horizons, only those in the Sturgeon Lake area host base-metal sulphide deposits, and they exhibit the most pronounced negative Eu anomalies of this group. (3) FIII felsic metavolcanic rocks are rhyolites and high-silica rhyolites characterized by relatively flat REE patterns, which may be subdivided into two types. FIIIa felsic metavolcanic rocks exhibit variable negative Eu anomalies, low Zr/Y, and intermediate abundances of HFS elements and Sr. Examples occur in the Noranda mining district of the Abitibi Belt. FIIIb felsic metavolcanic rocks exhibit pronounced negative Eu anomalies, low Zr/Y, high abundances of HFS elements, and low abundances of Sr. Examples occur in the Kamiskotia, Kidd Creek, Matagami, and Noranda mining districts, the Garrison Subgroup in the Abitibi Belt, and at the South Bay mine in the Confederation Lake area of the Uchi Belt. All of these FIII horizons, with the exception of Garrison, host important base-metal sulphide deposits.These geochemical variations are interpreted to reflect differences in the petrogenesis of the felsic magmas, specifically, their formation or degree of modification in high-level magma chambers, which also influenced the formation of massive base-metal sulphide deposits. Most massive base-metal sulphide deposits in the Superior Province are underlain by subvolcanic magma chambers, which have been interpreted to have supplied heat to drive the ore-forming hydrothermal systems. FIII and some FII felsic volcanic rocks are interpreted to have been derived from these high-level magma chambers, accounting for their distinctive geochemical signatures and their association with massive base-metal sulphide mineralization. In contrast, FI felsic volcanic rocks are interpreted to have been derived from a deeper source and are considered to have escaped significant high-level modification, accounting for their distinctive geochemical signatures and the lack of associated base-metal sulphide mineralization. With certain limitations, the geochemistry of felsic metavolcanic rocks therefore may be used as a guide to identify prospective horizons for massive base-metal sulphide exploration in the Superior Province.

Polyphase deformation and crustal evolution in the Pipestone Lake area of the Archean Wabigoon Subprovince, Superior Province, Canada

1999 ◽  
Vol 36 (3) ◽  
pp. 459-477 ◽  
Author(s):  
Garth R Edwards ◽  
Mel R Stauffer
Keyword(s):  
Shear Zone ◽  
Canadian Shield ◽  
Superior Province ◽  
Crustal Evolution ◽  
Lake Area ◽  
Polyphase Deformation ◽  
Crenulation Cleavage ◽  
East West

Archean supracrustal rocks in the western Wabigoon Subprovince, Superior Province, Canadian Shield, have undergone four phases of deformation, D1-D4. D1, confined to the oldest rocks, includes a large, refolded, reclined, isoclinal anticline (F1) with moderately developed axial-planar cleavage (S1). Rocks affected by D1 are overlain by a regional unconformity. D2 includes post-unconformity, steeply plunging, north-northeast-south-southwest-striking, isoclinal folds (F2) that are approximately coaxial with F1, but have contorted the F1 axial trace. D3 is represented by east-west-striking, steeply plunging folds at various scales (F3) which occur mainly in rocks near the regional Manitou Stretch - Pipestone Lake Shear Zone, also interpreted to be a D3 structure. D4 is represented by pervasive cleavage (S4), locally penetrative but mainly spaced, including crenulation cleavage, fractures, small faults, and brittle-ductile shears. S4 is parallel to the margin of the Jackfish Lake Pluton. D1-D3 are ascribed to convergence of the Wabigoon Subprovince with adjacent subprovinces, ending with formation of the Manitou Stretch - Pipestone Lake Shear Zone as a (presently) steep thrust and oblique-ramp structure. D4 is the result of either diapiric emplacement of the Jackfish Lake Pluton, or marginal strain intensification due to the rigidity of the older Ash Bay Dome during late north-south compression. Previously available zircon U-Pb geochronology provides a maximum age for D1 of 2728 Ma, and an approximate age for D4 of 2698 Ma. The unconformity developed between D1 and D2, 2725-2713 Ma.

Plume magmatism and crustal growth at 2.9 to 3.0 Ga in the Steep Rock and Lumby Lake area, Western Superior Province

Lithos ◽  
1999 ◽  
Vol 46 (1) ◽  
pp. 103-136 ◽  
Author(s):  
K.Y Tomlinson ◽  
D.J Hughes ◽  
P.C Thurston ◽  
R.P Hall
Keyword(s):  
Superior Province ◽  
Lake Area ◽  
Crustal Growth ◽  
Plume Magmatism

Bedrock geology of the Grand Lake area, Maine

1964 ◽  
Author(s):  
David Marcel Larrabee ◽  
Donald J.P. Swift
Keyword(s):  
Lake Area ◽  
Bedrock Geology

Preliminary geologic report on the Harris Lake area, northeastern Minnesota

1978 ◽  
Author(s):  
M.P. Foose ◽  
Roger W. Cooper
Keyword(s):  
Lake Area
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