Members of the Keweenawan Supergroup are exposed at the surface only in the Lake Superior region, particularly at the perimeter of the Midcontinent Rift System. To the southeast and southwest, they are covered by sedimentary rocks of Paleozoic age. At its thickest, the supergroup consists of about 20 kilometers (12 mi) of volcanic rocks overlain by about 10 kilometers (6.2 mi) of sedimentary rocks.[1]
The supergroup consists of the following members:[2]
The Powder Mill Group is reversely polarized except for intervals at the base and top of the upper Kallander Creek Volcanics.[4] The Portage Lake Volcanics and all younger formations have normal magnetic polarity.[5]
Nicholson, W.; Shirey, Steven B.; Schulz, Klaus J.; Green, John C. (1997). "Rift-wide correlation of 1.1 Ga Midcontinent rift system basalts: implications for multiple mantle sources during rift development" (PDF). Canadian Journal of Earth Sciences. 34 (4). NRC Research Press: 504–520. Bibcode:1997CaJES..34..504N. doi:10.1139/e17-041. Retrieved June 19, 2012.
January 01, 1970
keweenawan, supergroup, supergroup, volcanic, sedimentary, rocks, that, fill, midcontinent, rift, system, states, michigan, wisconsin, minnesota, about, kilometers, thick, formed, about, billion, years, contents, stratigraphy, magnetism, references, bibliograp. The Keweenawan Supergroup is a supergroup of volcanic and sedimentary rocks that fill the Midcontinent Rift System in the U S states of Michigan Wisconsin and Minnesota 1 2 It is about 30 kilometers 19 mi thick and it formed about 1 1 billion years ago 3 Contents 1 Stratigraphy 2 Magnetism 3 References 3 1 BibliographyStratigraphy editMembers of the Keweenawan Supergroup are exposed at the surface only in the Lake Superior region particularly at the perimeter of the Midcontinent Rift System To the southeast and southwest they are covered by sedimentary rocks of Paleozoic age At its thickest the supergroup consists of about 20 kilometers 12 mi of volcanic rocks overlain by about 10 kilometers 6 2 mi of sedimentary rocks 1 The supergroup consists of the following members 2 State Members Michigan Bergland Group Bessemer Quartzite Jacobsville Sandstone Oronto Group Powder Mill Group Wisconsin Bergland Group Bessemer Quartzite Oronto Group Powder Mill Group Bayfield Group Chengwatana Volcanic Group Minnesota Oronto Group Beaver Bay Complex Duluth Complex Fond du Lac Formation Hinckley Sandstone Hovland Diabase Complex North Shore Volcanic Group Puckwunge Formation Reservation River Diabase Complex Solor Church FormationMagnetism editThe Powder Mill Group is reversely polarized except for intervals at the base and top of the upper Kallander Creek Volcanics 4 The Portage Lake Volcanics and all younger formations have normal magnetic polarity 5 References edit a b Nicholson p 505 a b Geologic Unit Keweenawan GEOLEX Database United States Geological Survey Retrieved June 20 2012 Geology of the Porcupine Mountains PDF Michigan Department of Natural Resources p 1 Archived from the original PDF on January 18 2012 Retrieved June 19 2012 Nicholson pp 507 8 Nicholson p 508 Bibliography edit Nicholson W Shirey Steven B Schulz Klaus J Green John C 1997 Rift wide correlation of 1 1 Ga Midcontinent rift system basalts implications for multiple mantle sources during rift development PDF Canadian Journal of Earth Sciences 34 4 NRC Research Press 504 520 Bibcode 1997CaJES 34 504N doi 10 1139 e17 041 Retrieved June 19 2012 Retrieved from https en wikipedia org w index php title Keweenawan Supergroup amp oldid 1152757870, wikipedia, wiki, book, books, library,
