1-20 OF 107 RESULTS FOR

Keweenawan extrusives

Results shown limited to content with bounding coordinates.
Follow your search
Access your saved searches in your account

Would you like to receive an alert when new items match your search?
Close Modal
Sort by
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
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 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...
FIGURES | View All (14)
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...
FIGURES | View All (16)
Series: GSA Memoirs
Published: 01 January 1982
DOI: 10.1130/MEM156-p5
... The Lake Superior Basin and the Lake Superior syncline are differentiated as tectonic elements; the syncline is locally defined within and adjacent to the southwestern and southern portions of the basin. Formation of the basin apparently commenced with the extrusion of lava in sub-basins...
Journal Article
Published: 01 April 1994
Canadian Journal of Earth Sciences (1994) 31 (4): 698–708.
.... The data define two very clear features. One is a trough of low heat-flow values, which runs continuously for 650 km along the northern edge of the lake, with values ranging between 0.46 and 0.98 heat-flow units (HFU) (19.2–41.0 mW/m 2 ). This feature correlates with surface exposure of Keweenawan mafic...
Journal Article
Journal: Geology
Published: 01 December 1982
Geology (1982) 10 (12): 645–649.
... a structural trough within the Precambrian beneath the Michigan Basin. These deep reflections, which correlate spatially with the mid-Michigan gravity and magnetic high, are interpreted to be a pile of basaltic extrusive rocks intercalated with clastic rocks and correlative with Keweenawan volcanics exposed...
Journal Article
Journal: GSA Bulletin
Published: 01 November 1971
GSA Bulletin (1971) 82 (11): 3221–3226.
... (~ 1,100 m.y.) to other intrusive and extrusive middle Keweenawan rocks of the Lake Superior region. 21 6 1971 Copyright © 1971, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. 1971 ...
Journal Article
Journal: Economic Geology
Published: 01 May 1942
Economic Geology (1942) 37 (3): 173–187.
... on the deeply eroded surface of a basement complex is a great thickness of Keewatin lavas. After their extrusion they were folded, faulted, and intruded by peridotite. A long period of alteration and erosion followed, before the final intrusion of many small Keweenawan dikes. It is concluded that the Keweenawan...
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...
FIGURES | View All (12)
Series: Geological Society, London, Special Publications
Published: 09 March 2022
DOI: 10.1144/SP518-2020-221
EISBN: 9781786205810
... Abstract Continental flood basalt provinces (CFBPs) are large igneous features formed by the extrusion of massive amounts of lavas that require significant evolution within the lithosphere. Although sequential lava flows are effective probes of magmatic systems, CFBPs are typically poorly...
FIGURES | View All (14)
Journal Article
Journal: Geology
Published: 01 June 2014
Geology (2014) 42 (6): 475–478.
...Nicholas L. Swanson-Hysell; Seth D. Burgess; Adam C. Maloof; Samuel A. Bowring Abstract The Keweenawan Midcontinent Rift of North America records significant continental rifting between ca. 1110 and 1085 Ma, and preserves the most detailed paleomagnetic record of plate motion of any continent...
FIGURES
Series: Special Publications of the Society of Economic Geologists
Published: 01 January 2010
DOI: 10.5382/SP.15.2.06
EISBN: 9781629490403
... large volumes of mafic magma and crustal rocks in either intrusive or extrusive settings may have resulted in contamination that triggered sulfide saturation or melting of sulfides within country rocks. Staging chambers and conduits in the subvolcanic environment and embayments associated with channels...
FIGURES | View All (13)
Journal Article
Published: 01 April 1997
Canadian Journal of Earth Sciences (1997) 34 (4): 464–475.
...Robert S. White Abstract The tectono-magmatic history of the Midcontinent rift system can be explained by the presence of a mantle plume bringing elevated-temperature mantle beneath the rift system at about 1110 Ma. Huge volumes of extrusive and intrusive igneous rocks were generated as abnormally...
Journal Article
Journal: Geophysics
Published: 01 February 1997
Geophysics (1997) 62 (1): 365–380.
... as a possible source of volcanic rocks in southwestern Ohio, and numerous mafic bodies related presumably to Keweenawan rifting and Grenville tectonics. Correlative anomaly minima include several isolated features that may define felsic terranes of the upper crust, and ringed features around some of the larger...
Journal Article
Journal: Economic Geology
Published: 01 December 1992
Economic Geology (1992) 87 (8): 1945–1962.
... of the Noril'sk region are (1) a hot region in the mantle giving rise to vast amounts of basalt, (2) continental-scale rifting, (3) major faults serving as controls for extrusive and intrusive magmatism, (4) crustal contamination of magma, (5) chalcophile element depletion of contaminated magma, (6) intrusion...
Journal Article
Journal: AAPG Bulletin
Published: 01 August 1983
AAPG Bulletin (1983) 67 (8): 1325.
... the surface exposure of the Keweenawan Supergroup in the Lake Superior basin southwest in the subsurface through Wisconsin, Minnesota, Iowa, Nebraska, and Kansas. The Mid-Continent gravity high, which includes the highest gravity values within the continental United States, has been interpreted historically...
Journal Article
Journal: Economic Geology
Published: 01 August 1969
Economic Geology (1969) 64 (5): 551–563.
...George A. Armbrust Abstract Precambrian host rock, possible middle Keweenawan hydrothermal alteration-magmatic extrusion association GeoRef, Copyright 2008, American Geological Institute. 1969 ...
Journal Article
Journal: Economic Geology
Published: 01 November 1959
Economic Geology (1959) 54 (7): 1250–1277.
... of the Keweenawan series throughout the Lake Superior basin is like that of Keweenaw Peninsula, indicating that the mineral zones have regional extent. Cu concentrations are commonly near the boundary of the quartz zone, but may lie well within the quartz zone where quartz is not abundant. Most barren areas...
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...