The Great Lakes tectonic zone — A major crustal structure in central North America

Sims, P.K.; Card, K. D.; Morey, G.B.; Peterman, Zell E.

doi:10.1130/0016-7606(1980)91<690:tgltza>2.0.co;2

Cited by 114 publications

(26 citation statements)

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“…It is apparent that at the southern end (in Kansas), crustal separation must become negligible. Chandler (1983) has recently analyzed offsets magnetic anomalies in the western Lake Superior region and concludes that crustal separation was about 60 km, consistent with earlier estimates of 65-75 km (Chase & Gilmer 1973) and 70 km (Sims et al 1980). The width the anomaly in these areas is comparable with or slightly wider than the rest of the rift system (excluding the Lake Superior basin), which indicates that the rift never opened more than about 60-75 km.…”

Section: Deep Structuresupporting

confidence: 62%

“…In this region the Archean rocks are generally divided into a northern granite-greenstone terrane that has remained relatively stable since it formed 2.62.8 Gyr ago and a southern gneiss-migmatite terrane that formed 2.6-3.6 Gyr ago but was subjected to extensive deformation during Early Proterozoic orogenies (Morey & Sims 1976). The Lake Superior basin occurs within the granite-greenstone terrane, just to the north of the boundary (Great Lakes Tectonic Zone; Sims et al 1980) between the terranes. The rift system broadens within the Lake Superior basin, it becomes much wider, and the regional trend changes from NE-SW (MGA) to NW-SE (mid-Michigan segment).…”

Section: Re~tional Geolo~tic Setting7mentioning

confidence: 99%

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The Midcontinent Rift System

Schmus¹

1985

Annual Review of Earth and Planetary Sciences

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Section: Deep Structuresupporting

confidence: 62%

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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“…2). Correlation of the Murray Fault System with the Great Lakes tectonic zone to the W (Sims et al 1980) indicates that, during the later stages of the Penokean orogeny, the Murray Fault acted as a dextral transpressive system in its western sector and, to a lesser degree, with the same sense in its eastern sector. The extent to which the Penokean orogeny distorted the Sudbury structure and changed the original shape of the SIC is a debatable point.…”

Section: The Penokean Orogenymentioning

confidence: 98%

Tectonic influences on the morphometry of the Sudbury impact structure: Implications for terrestrial cratering and modeling

Spray

Butler²,

Thompson

2004

Meteorit & Planetary Scien

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Abstract-Impact structures developed on active terrestrial planets (Earth and Venus) are susceptible to pre-impact tectonic influences on their formation. This means that we cannot expect them to conform to ideal cratering models, which are commonly based on the response of a homogeneous target devoid of pre-existing flaws. In the case of the 1.85 Ga Sudbury impact structure of Ontario, Canada, considerable influence has been exerted on modification stage processes by late Archean to early Proterozoic basement faults. Two trends are dominant: 1) the NNW-striking Onaping Fault System, which is parallel to the 2.47 Ga Matachewan dyke swarm, and 2) the ENE-striking Murray Fault System, which acted as a major Paleoproterozoic suture zone that contributed to the development of the Huronian sedimentary basin between 2.45-2.2 Ga. Sudbury has also been affected by syn-to post-impact regional deformation and metamorphism: the 1.9-1.8 Ga Penokean orogeny, which involved NNW-directed reverse faulting, uplift, and transpression at mainly greenschist facies grade, and the 1.16-0.99 Ga Grenville orogeny, which overprinted the SE sector of the impact structure to yield a polydeformed upper amphibolite facies terrain. The pre-, syn-, and post-impact tectonics of the region have rendered the Sudbury structure a complicated feature. Careful reconstruction is required before its original morphometry can be established. This is likely to be true for many impact structures developed on active terrestrial planets.Based on extensive field work, combined with remote sensing and geophysical data, four ring systems have been identified at Sudbury. The inner three rings broadly correlate with pseudotachylyte (friction melt) -rich fault systems. The first ring has a diameter of ~90 km and defines what is interpreted to be the remains of the central uplift. The second ring delimits the collapsed transient cavity diameter at ~130 km and broadly corresponds to the original melt sheet diameter. The third ring has a diameter of ~180 km. The fourth ring defines the suggested apparent crater diameter at ~260 km. This approximates the final rim diameter, given that erosion in the North Range is <6 km and the ring faults are steeply dipping. Impact damage beyond Ring 4 may occur, but has not yet been identified in the field. One or more rings within the central uplift (Ring 1) may also exist. This form and concentric structure indicates that Sudbury is a peak ring or, more probably, a multi-ring basin. These parameters provide the foundation for modeling the formation of this relatively large terrestrial impact structure.

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“…The alteration of quartz (after Van Schmus et al, 1987). (b) Geologic map of the Lake Superior region showing the southern limit of the Great Lakes tectonic zone (Sims et al, 1980). The Powder Mill Group includes the Siemens Creek Formation and the overlying Kallander Creek Formation.…”

Section: Country Rocksmentioning

confidence: 99%