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.

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.

Tectonic evolution of two greenstone belts from the Superior Province in Manitoba

1978 ◽  
Vol 15 (11) ◽  
pp. 1808-1816 ◽  
Author(s):  
R. G. Park ◽  
I. F. Ermanovics
Keyword(s):  
Tectonic Evolution ◽  
Superior Province ◽  
The North ◽  
Crenulation Cleavage ◽  
Facies Metamorphism ◽  
Tonalitic Gneiss ◽  
Uniform Stress Field ◽  
Greenstone Belts ◽  
East West ◽  
Lower Group

The Bigstone Lake and Stevenson Lake greenstone belts are two areas of supracrustal rocks surrounded by quartz diorite to granodiorite plutons and by small patches of tonalitic gneiss interpreted as basement to the greenstone belts. The supracrustal sequence is divided into a lower, mainly volcanic, group correlated with the Hayes River Group of Island Lake and an unconformable upper group with roughly equal proportions of sediments and volcanics correlated with the Island Lake 'Series'. The lower group consists of about 4600 m of basaltic and andesitic pillow lavas with minor greywackes and dacitic volcanics. It is partly replaced at the base by the bordering plutons and cut out at the top by the unconformable upper group, which consists of about 2300 m of greywackes, arkoses, and mudstones above a basal conglomerate containing boulders derived from the lower group and from the basement. A further 2100 m of volcanics overlies these sediments.The supracrustal rocks show three phases of deformation. The first, F1, produced major northeast–southwest and east–west synclines. S1 foliation was developed under greenschist facies to low amphibolite facies metamorphism. F2 produced smaller scale steep east–west folds with a crenulation cleavage. Subsequent deformation resulted in chevron folds and conjugate shear belts.The intrusion of the plutons commenced before the F1 deformation and partly controlled it, but a further period of plutonic intrusion occurred after F1 and before F2.The north–south compressive stress prevailing during F2 and later deformation under waning metamorphism implies that the batholiths in the vicinity of the greenstone belts had completely solidified and that the crust was rigid enough to transmit a uniform stress field. The dominance of east–west structural grain in this part of the Superior Province indicates that these conditions were general.

THE SODA CREEK FISH CREEK SHEAR ZONE: USING MULTIPLE GEOCHRONOLOGIC METHODS TO UNRAVEL THE PROTEROZOIC STRUCTURAL HISTORY OF POLYPHASE DEFORMATION IN HIGHLY DEFORMED ROCKS

2016 ◽  
Author(s):  
Bart T. Cubrich ◽  
◽  
Kevin R. Chamberlain ◽  
Ernest Duebendorfer ◽  
Michael L. Williams ◽  
...  
Keyword(s):  
Shear Zone ◽  
Polyphase Deformation ◽  
Structural History ◽  
History Of

HADEAN TO NEOARCHEAN CRUSTAL EVOLUTION IN A SINGLE SAMPLE OF THE CEDAR LAKE GNEISS, WESTERN SUPERIOR PROVINCE, CANADA

2020 ◽  
Author(s):  
J.W.D. Strong ◽  
◽  
P. Cawood ◽  
A.R. Cruden ◽  
O. Nebel ◽  
...  
Keyword(s):  
Single Sample ◽  
Superior Province ◽  
Crustal Evolution

UNDEFINING THE SNOWY SHEAR ZONE --- A TECTONOMETAMORPHIC APPROACH TO UNDERSTANDING POLYPHASE DEFORMATION WITHIN THE WESTERN ABSAROKA-BEARTOOTH MOUNTAINS OF MONTANA

2019 ◽  
Author(s):  
Jeffrey R. Webber ◽  
◽  
Alex Avelar Flores ◽  
Andrew Del Turco ◽  
Thomas Kalakay ◽  
...  
Keyword(s):  
Shear Zone ◽  
Polyphase Deformation

scholarly journals METAMORPHISM OF THE CANADIAN SHIELD, ONTARIO, CANADA. I. THE SUPERIOR PROVINCE

2000 ◽  
Vol 38 (2) ◽  
pp. 287-317 ◽  
Author(s):  
R. M. Easton
Keyword(s):  
Canadian Shield ◽  
Superior Province

Some new measurements of heat flow in the Superior Province of the Canadian Shield

1987 ◽  
Vol 24 (7) ◽  
pp. 1486-1489 ◽  
Author(s):  
Malcolm Drury ◽  
Alan Taylor
Keyword(s):  
Standard Deviation ◽  
Heat Flow ◽  
Canadian Shield ◽  
Superior Province ◽  
Flow Measurements ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Climatic Variations ◽  
The Mean ◽  
A Site

Borehole heat-flow measurements are reported from six new sites in the Superior Province of the Canadian Shield. Values adjusted for glaciation effects, but not for Holocene climatic variations, range from 42 to 56 mW/m2. When these new values are combined with 21 previously published borehole values the mean is 42 mW/m2 with a standard deviation of 11 mW/m2. The data for a site on the Lac du Bonnet batholith suggest that the batholith has a thin veneer, less than 3 km, of rock of high radiogenic heat production at the surface.

Thermometry and barometry of some amphibolite–granulite facies rocks from the Otter Lake area, southern Quebec

1982 ◽  
Vol 19 (9) ◽  
pp. 1759-1774 ◽  
Author(s):  
Dexter Perkins III ◽  
Eric J. Essene ◽  
Louise Annette Marcotty
Keyword(s):  
New York ◽  
Thermal Gradient ◽  
Granulite Facies ◽  
Metamorphic Grade ◽  
Lake Area ◽  
Temperature And Pressure ◽  
East West

Grenville rocks from a 2500 km2 area centered on Otter Lake, Quebec (some 75 km northwest of Ottawa) are in the uppermost amphibolite to lower granulite facies; orthopyroxene occurs occasionally in both metabasic and charnockitic rocks. The temperature of metapmorphism was approximately 675 °C, based upon oxide, feldspar, and garnet–clinopyroxene thermometry. Little thermal gradient could be detected across the area. Carbonate thermometry, using reintegrated calcite compositions, yielded lower temperatures of 600 °C (maximum), while garnet–biotite and other Kd thermometers yielded scattered and for the most part unreasonable results. Metamorphic pressure, calculated from the reaction anorthite = grossular + sillimanite + quartz, was 5.0 ± 0.5 kbar(500 ± 50 MPa). Similar calculations based upon the reactions garnet + quartz = anorthite + orthopyroxene and garnet + quartz = anorthite + clinopyroxene yielded pressures of 5.5–7.0 kbar (550–700 MPa). Pressure calculations based upon assemblages of cordierite–garnet–sillimanite–quartz were less precise, but agreed with the outer estimates. Similar metamorphic temperatures and slightly lower pressures have been estimated for the Adirondack Lowlands of New York. In the Morin Highlands, 100 km east of Otter Lake, and in the Adirondack Highlands, 100 km east of the Adirondack Lowlands, temperatures of metamorphism (700–800 °C) and pressures of metamorphism (6–9 kbar (600–900 MPa)) are both higher. Thus it appears that over an approximate 300 km north–south direction nearly constant metamorphic conditions prevailed at Grenville time. In the east–west direction significant variations in metamorphic grade are recorded; both temperature and pressure markedly increase to the east.

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