4: The pre-Keweenawan tectonic history of southern Canadian Shield and its influence on formation of the Midcontinent Rift

Klasner, J.S.; Cannon, William F.; Schmus, W. R. Van

doi:10.1130/mem156-p27

Cited by 41 publications

(15 citation statements)

References 26 publications

(39 reference statements)

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“…, however, found no compelling evidence for the existence of a triple junction in the Lake Superior region. If no triple junction was formed, there exists the alternative: the complex was emplaced where a late transverse fracture intersected the rift, e.g., the Trans Superior Tectonic Zone of Klasner et al (1982). Halls (1978) and have noted that the southwest arm of the Keeweenawan rift in the Lake Superior region is an extension of the Mid Continental Gravity High, and is a linear axial positive gravity anomaly.…”

Section: Regional Tectonic-petrogenetic Settingmentioning

confidence: 97%

A gravity study of the Coldwell Complex, northwestern Ontario and its petrological significance

Mitchell¹,

Platt²,

Cheadle³

1983

Can. J. Earth Sci.

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Gravity studies of the Coldwell alkaline complex show that the complex is associated with a positive gravity anomaly. The anomaly indicates that a significant volume of dense material occurs below the current levels of exposure of principally felsic rocks. A new high-resolution gravity profile used to model the infrastructure of the complex shows that the felsic rocks form a 3-5 km thick layer over a differentiated basic intrusion. This intrusion is interpreted to consist of a layer of gabbro 3-5 km in thickness underlain by 3 km of peridotite and (or) pyroxenite. Intrusion of the basic magma was associated with Keeweenawan continental rifting. The presence of large volumes of basic magma supports the hypothesis that some of the Coldwell felsic rocks were derived by differentiation of a basic parent.Une ktude gravimktrique du complexe alcalin de Coldwell dkmontre l'association de ce complexe avec une anomalie de gravitk positive. Cette anomalie indique qu'un volume considkrable de matkriaux denses est sous-jacent aux niveaux habituellement exposks des principales roches felsitiques. Un profil de gravitk rkcent de grande prkcision est utilisk pour modkliser l'infrastructure de ce complexe form6 d'une couche de 3-5 krn d'kpaisseur de roches felsitiques reposant sur une intrusion basique diffkrencike. Cette intrusion est possiblement composke d'une couche de gabbro de 3-5 km d'kpaisseur sus-jacente a 3 km de pkridotite et (ou) pyroxknite. L'intrusion du magma basique est relike au rifting continental keweenavien. La prksence d'un grand volume de magma basique appuie l'hypothkse qu'une portion des roches felsitiques de Coldwell provient de la diffkrenciation d'un magma basique apparentke.[Traduit par le journal]Can.

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Section: Regional Tectonic-petrogenetic Settingmentioning

confidence: 97%

A gravity study of the Coldwell Complex, northwestern Ontario and its petrological significance

Mitchell¹,

Platt²,

Cheadle³

1983

Can. J. Earth Sci.

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“…The Proterozoic crustal basement rocks in the midcontinent region formed 1300-1900 Myr ago and consist of 1600-1900-Myr-old new crust [which probably formed as orogenic continental margin assemblages (Van Schmus & Bickford 1981)] and 1300-1500-Myr-old anorogenic plutonic and volcanic rocks that formed by remelting of the older Proterozoic crust (Thomas et al 1984, Nelson DePaolo 1985, Anderson 1983). According to Klasner et al (1982), orientation of various segments of the rift system may be controlled by www.annualreviews.org/aronline Annual Reviews structures within the Early Proterozoic basement. However, knowledge of structures in the basement is very limited, and other factors could be dominant.…”

Section: Re~tional Geolo~tic Setting7mentioning

confidence: 99%

The Midcontinent Rift System

Schmus¹

1985

Annual Review of Earth and Planetary Sciences

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“…The correspondence of the trends of the rift segments with older tectonic zones has been noted by several authors including Klasner et al (1982), Carlson (1988a), and Sims (1990; Fig. 1).…”

Section: Rift Frameworkmentioning

confidence: 85%

Tectonic implications and influence of the Midcontinent Rift System in Nebraska and adjoining areas

Carlson¹

1997

Middle Proterozoic to Cambrian Rifting, Central North America

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Southeastern Nebraska is underlain by EarlyProterozoic rocks of the Central Plains (1,600 to 1,800 Ma) and Penokean (1,830 to 1,890 Ma) Provinces. The Midcontinent Rift System was imposed upon and reflects the preexisting tectonic grain of the older basement. During Paleozoic time several periods of structural change occurred related to the Midcontinent Rift System. In the same geographic area, there was successive development of the Southeast Nebraska arch, the North Kansas basin, the Nemaha uplift, and the Table Rock arch. The locations of these regional features were controlled by the patterns established by rift tectonics. Features such as the Eastern Nebraska high, the Abilene Anticline, the Union fault, and the Burchard fault are reactivations of specific rift features.

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4: The pre-Keweenawan tectonic history of southern Canadian Shield and its influence on formation of the Midcontinent Rift

Cited by 41 publications

References 26 publications

A gravity study of the Coldwell Complex, northwestern Ontario and its petrological significance

A gravity study of the Coldwell Complex, northwestern Ontario and its petrological significance

The Midcontinent Rift System

Tectonic implications and influence of the Midcontinent Rift System in Nebraska and adjoining areas

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