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Keweenawan extrusives by basic intrusives

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Journal Article
Journal: GSA Bulletin
Published: 01 August 1943
GSA Bulletin (1943) 54 (8): 1211–1226.
...GEORGE M. SCHWARTZ Abstract The basalts and rhyolites of the Keweenawan of Minnesota have been invaded by the huge mass of the Duluth gabbro as well as by a great number of smaller sills, dikes, and irregular intrusives, mainly diabase. Close to the contact the flows are generally altered to fine...
Journal Article
Journal: GSA Bulletin
Published: 01 May 1954
GSA Bulletin (1954) 65 (5): 401–442.
... belt of basic extrusives, Keweenawan in age, with flows the oldest, gabbro next, and granophyre the youngest. Still younger are basic dikes that show preferred orientation. The complex is on the steeply dipping south limb of the Lake Superior geosyncline. The gabbro was intruded between flow units...
Journal Article
Journal: AAPG Bulletin
Published: 01 December 1967
AAPG Bulletin (1967) 51 (12): 2351–2380.
... the basement for younger extensive volcanic-intrusive complexes. Keweenawan basalt and associated sedimentary rock units are nearly continuous from northeastern Kansas to the outcrop belt around Lake Superior. An offset in trend and a break in continuity near the Nebraska-Kansas border have been postulated...
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Journal Article
Published: 18 January 2018
Canadian Journal of Earth Sciences (2019) 56 (1): 1–15.
... of the Keweenaw peninsula’s copper deposits are diverse and poorly constrained in time. Table 1. Stratigraphy of the Keweenaw Peninsula, modified from Bornhorst and Barron (2011) . In this paper, we use the estimated rates of volcanic extrusion, of clastic gray beds deposition and of Keweenawan...
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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
Published: 01 September 2001
The Journal of Geology (2001) 109 (5): 585–601.
... Jurassic Palisades sill. Each of these three formations consists of multiple flows of quartz normative tholeiitic flood basalt that extruded over a widespread eastern North American terrain (Puffer 1992 ; McHone and Puffer, in press ). They are, in general, subaerial extrusions, but local pillow texture...
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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.
... from Shirey et al. ( 1994 ). Keweenawan volcanics data from Paces ( 1988 ). As discussed, the majority of intrusive rocks in the Nipigon Embayment are characterized by depleted incompatible element abundances and negative Nb anomalies that are not typical of modern OIB but common to many CFB...
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Journal Article
Journal: Lithosphere
Publisher: GSW
Published: 27 February 2021
Lithosphere (2021) 2021 (1): 8836546.
... of celadonite is recorded in the lower part of the NSVG and occurred ca. 30 myrs after the emplacement of the Silver Bay aplite intrusion in the upper part of the NSVG. Burial rates are determined to be 0.04 km·Ma -1 and 0.10 km·Ma -1 . The hydrothermal alteration under low-temperature burial conditions clearly...
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Journal Article
Journal: GSA Bulletin
Published: 25 May 2022
GSA Bulletin (2023) 135 (1-2): 449–466.
... or be onlapped by them. This feature is expressed in bathymetry as Fisherman Reef ( Fig. 4 at F) and lies along strike of the northern half of Isle Royale. We interpret this discordant unit as a late Keweenawan igneous intrusion and we note that it shows no sign of deformation or offset by a major fault...
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Journal Article
Published: 01 September 1989
Journal of the Geological Society (1989) 146 (5): 799–808.
... in the magnetic properties of the basic intrusions across the metamorphic boundary at Loch Torridon. To illustrate this (Table 1) we have separated those sites (21-28) from the Scourian relict terrane at Rhuadh Mheallan from nine sites (12-20) occupying the transition zone in which only dyke margins have been...
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: 10 November 2016
Canadian Journal of Earth Sciences (2016) 53 (11): 1121–1141.
... ). Geochemical and isotopic compositions of the Triassic Shuiquangou ( Fig. 1A ) volcanic rocks and basic-ultrabasic complex and granitic intrusive rocks from the northern margin of the NCC shows that the asthenosphere was involved in the formation of these rocks ( Zhang et al. 2010 ). However, no mid-ocean...
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Journal Article
Journal: AAPG Bulletin
Published: 01 October 1944
AAPG Bulletin (1944) 28 (10): 1417–1429.
... sedimentary beginning with arkosic elastics below and passing upward into enormous bodies of more or less cherty limestone containing obscure algal bodies as its only fossils. It also contains economically important sedimentary iron ores, a widespread tillite, and local extrusive basic lavas. The Sinian...
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Journal Article
Journal: Interpretation
Published: 26 October 2020
Interpretation (2020) 8 (4): SS63–SS85.
...V. J. S. Grauch; Eric D. Anderson; Samuel J. Heller; Esther K. Stewart; Laurel G. Woodruff Abstract The Midcontinent Rift System (MRS) is a 1.1 Ga sequence of voluminous basaltic eruptions and multiple intrusions followed by widespread sedimentation that extends across the Midcontinent and northern...
Journal Article
Journal: AAPG Bulletin
Published: 01 September 1992
AAPG Bulletin (1992) 76 (9): 1384–1401.
... stratigraphic test. The strata of the McArthur basin are middle Proterozoic (1.4-1.8 Ga), as are the sequences described here. The presence of large quantities of both intrusive and extrusive igneous rocks in the North American mid-continent suggest that any middle Proterozoic sedimentary strata...
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Journal Article
Published: 01 January 1999
Rocky Mountain Geology (1999) 34 (2): 183–194.
... include the similar time-lag of emplacement after orogenesis (50–60 m.y.), the close association in both time and space between post-orogenic uplift and intrusion, the depth of emplacement, and the long-lived tectonic quiescence (crustal stabilization) that followed magma emplacement. Post-tectonic...
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Journal Article
Journal: Economic Geology
Published: 01 May 2016
Economic Geology (2016) 111 (3): 783–794.
... Copper commonly occurs as sulfide and oxide minerals in nature. Native copper, zero-valance state copper mineral, is less common and occurs in a diversity of environments such as basaltic lava flows, mafic and ultramafic intrusions, clastic sediments, oxidized copper ores, and modern swamps ( Cornwall...
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Journal Article
Published: 14 June 2010
Canadian Journal of Earth Sciences (2010) 47 (5): 695–739.
..., with broad lines marking dyke swarms, and generalized polygons marking other units (sills, volcanics, layered intrusions). Stars mark plume centres identified as the convergence point of radiating dyke swarms. Blue lines mark the inferred portion of a breakup margin that is potentially linked to the given...
Journal Article
Journal: Interpretation
Published: 09 February 2018
Interpretation (2018) 6 (2): T257–T270.
... trend, could have formed as part of the intrusion process, as tectonic faults, or a combination of both processes. Our preferred interpretation is that discontinuities are small faults with varying senses of offset. The most prominent of these is a narrow, well-defined northwest-striking crest...