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Keweenawan extrusives metamorphosed

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Journal Article
Journal: AAPG Bulletin
Published: 01 December 1967
AAPG Bulletin (1967) 51 (12): 2351–2380.
... position. Dash-double dot lines = generalized orogenic trends lines. Note truncation of older trends by younger ones. Figure 13D also shows unmetamorphosed or slightly metamorphosed Precambrian supracrustal rocks regardless of age. Solid black = Keweenawan basalt and associated sedimentary rocks; dots...
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Journal Article
Journal: AAPG Bulletin
Published: 01 September 1975
AAPG Bulletin (1975) 59 (9): 1562–1584.
... intrusive and extrusive rocks and mafic and felsic gneisses of the Grenville province. The Grenville front strikes south-southwest from Saginaw Boy to west of the Howell anticline and from there due south to the AAichigan Ohio boundary. A Keweenawan rift zone choracterized by mafic intrusive and extrusive...
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Journal Article
Published: 01 August 1969
Canadian Journal of Earth Sciences (1969) 6 (4): 555–568.
... at depths of about 10 km beneath Lake Superior. Amphibole-bearing volcanics, hitherto unreported, were sampled in the basal parts of the Keweenawan extrusive sequence, and represent a higher grade of regional metamorphism than commonly found in the Portage Lake Series. Since metamorphic grade appears...
Journal Article
Journal: AAPG Bulletin
Published: 01 August 1932
AAPG Bulletin (1932) 16 (8): 737–740.
... of a large part of the Nonesuch formation, which is distinctive because of its dark gray to black color, the sedimentary rocks of the Keweenawan are red. The middle and lower divisions of the Keweenawan include ferromagnesian types of lava flows, intrusive and extrusive felsites, and other igneous rocks...
FIGURES
Journal Article
Published: 18 January 2018
Canadian Journal of Earth Sciences (2019) 56 (1): 1–15.
... event also created the major northwest-dipping Keweenaw thrust fault along the middle of the peninsula ( Fig. 2 ) and extensive co-eval block faulting throughout the Keweenawan strata ( Bornhorst 1997 ). Cannon et al. (1993) reported 16 Rb–Sr biotite dates for metamorphosed Archean to Middle...
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Journal Article
Journal: AAPG Bulletin
Published: 01 August 1985
AAPG Bulletin (1985) 69 (8): 1208–1216.
... , Radiometric ages of Keweenawan intrusions and extrusions in Michigan and adjacent areas (abs.) : GSA Abstracts with Programs , v. 4 , p. 470 – 471 . Chaudhuri , S. , 1975 , Geochronology of upper and middle Keweenawan rocks of Michigan (abs.) : Marquette, Northern Michigan University...
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Journal Article
Published: 14 August 2019
Canadian Journal of Earth Sciences (2019) 56 (9): 932–947.
... ) has an arcuate subsurface trace northward from Arkansas through Lake Superior and back southward to Tennessee ( Stein et al. 2016 ) ( Fig. 1 ). However, extensive exposures of the Keweenawan rocks occur only around Lake Superior where the main stage of rift extension and volcanic extrusion spanned...
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Journal Article
Journal: AAPG Bulletin
Published: 01 February 1926
AAPG Bulletin (1926) 10 (2): 190–196.
... on the northeast-to-southwest-trending axis of part of the old Laurentian Mountains of pre-Cambrian age. Since their original folding these mountains have been subjected to base-leveling, folding, faulting, various types of intrusions, and extrusive vulcanism, all antedating the Cambrian, and the whole area has...
FIGURES
Journal Article
Published: 03 May 2007
Canadian Journal of Earth Sciences (2007) 44 (3): 389–412.
... of the basin. Not only can the geochemical stratigraphy of the volcanics and its causative factors be derived from this sequence, but also the sedimentary units furnish information on the paleogeography at the time of extrusion and, by extension, the style of subsidence. Together these have the capacity...
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Journal Article
Journal: Geology
Published: 01 December 2015
Geology (2015) 43 (12): 1051–1054.
... thrusts dipping at shallow angles to the southeast. One, known as the Allochthon Boundary thrust (ABT), extends the full length of the Grenville Province ( Fig. 1 ) and separates metamorphosed Laurentian rocks within the parautochthon to the northwest from gneissic, granitic, anorthositic...
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Journal Article
Journal: AAPG Bulletin
Published: 01 April 1974
AAPG Bulletin (1974) 58 (4): 674–684.
... formed at deeper crustal levels, subsequently have been upwarped to the basement surface, and may be part of an earlier orogenic period. They include lenses of infolded metamorphosed sediments, as well as intrusive granite and basic plutonic rocks. It is assumed that the crustal complex is older than...
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Journal Article
Published: 28 August 2007
Canadian Journal of Earth Sciences (2007) 44 (8): 1087–1110.
... are highly metamorphosed, to a degree generally associated with the mafic to ultramafic intrusions rather than the diabase sills. The Jackfish sill consists of medium-grained, intergranular to subophitic-textured olivine gabbro with locally 15% to 25% olivine near the contacts and medium- to coarse-grained...
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Journal Article
Journal: AAPG Bulletin
Published: 01 September 1992
AAPG Bulletin (1992) 76 (9): 1384–1401.
... and predate or are contemporaneous with the 1.3-1.5 Ga crystallization ages of the granites and rhyolites. Though these layered rocks have a spatial association with igneous rocks and thus have likely been metamorphosed, the possibility that they contain Precambrian hydrocarbons that escaped heating is as yet...
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Journal Article
Published: 01 January 1999
Rocky Mountain Geology (1999) 34 (2): 183–194.
... of its more restricted exposures there. Because of this, greater attention will be paid here to the western Penokean orogen. The plutonic terrane in central Minnesota consists dominantly of little-deformed late- and post-Penokean plutons intruded into metamorphosed Archean and Paleoproterozoic...
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Journal Article
Journal: Economic Geology
Published: 01 June 2015
Economic Geology (2015) 110 (4): 983–1008.
... and metavolcanic flows that was surrounded and metamorphosed during emplacement of the Duluth Complex ( Patelke, 1996 ). The incompatible trace element ratios Ce/Y and Nb/Zr for the Fine-Grained Series are within the range of values for the tholeiitic intrusive and extrusive rocks of the Nipigon sills...
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Journal Article
Published: 01 August 2010
The Canadian Mineralogist (2010) 48 (4): 711–728.
... Archean greenstone belts, where they are associated with mafic intrusive and extrusive rocks ( Ashwal 1993 , Ashwal & Myers 1995 ). Where preserved, their primary textures are distinctive, being characterized by equidimensional megacrysts (up to 30 cm diameter) of calcic (usually >An 80...
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Journal Article
Published: 08 August 2007
Canadian Journal of Earth Sciences (2007) 44 (8): 1041–1053.
... portions of the area are underlain by the Wabigoon, Quetico, and Wawa subprovinces, respectively. The Wabigoon and Wawa (ca. 3.0 to 2.7 Ga) are volcano-plutonic subprovinces, containing several greenstone belts. The intervening Quetico subprovince (ca. 2.7 Ga) consists of metamorphosed clastic sedimentary...
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Journal Article
Published: 10 November 2016
Canadian Journal of Earth Sciences (2016) 53 (11): 1121–1141.
... and Ernst 2004 ∼2.0 Ga Tectonic regime change Hoffman 1988 ; Ernst et al. 1995 ; Ernst 2014 ∼1.9–1.6 Ga Penokean orogeny Away from the Superior Craton Schulz and Cannon 2007 ∼1.8 Ga Trans-Hudson orogeny Eaton and Darbyshire 2010 ∼1.1 Ga Keweenawan Mid-continent rift...
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Journal Article
Journal: Economic Geology
Published: 01 May 2016
Economic Geology (2016) 111 (3): 783–794.
...-4 Fine-grained altered basalt – In veins Hekinian (1974) , von der Borch et al. (1974) 38-1 Fine-grained medium gray basalt – In thin veins 29-282 Off the Tasmanian west coast 18-3 Fine-grained extrusive pillow basalt As specks In calcite veins Ovenshine et al. (1975...
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Journal Article
Published: 01 January 2003
Journal of the Geological Society (2003) 160 (1): 29–37.
... and pelites in the Mount Barren Group that have been metamorphosed to mid- to upper-amphibolite grade. Metamorphic conditions of 625–560 °C and 6–11 kbar were estimated from garnet–biotite geothermometry and garnet–staurolite–kyanite–biotite geothermobarometry by Wetherley (1998) . 15 7 2002 31 8...
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