Guidebook 11. Field Trip Guidebook for the Keweenawan (Upper Precambrian) North Shore Volcanic Group, Minnesota

Loading...
Thumbnail Image

View/Download File

Persistent link to this item

Statistics
View Statistics

Journal Title

Journal ISSN

Volume Title

Title

Guidebook 11. Field Trip Guidebook for the Keweenawan (Upper Precambrian) North Shore Volcanic Group, Minnesota

Published Date

1979

Publisher

Minnesota Geological Survey

Type

Map
Report

Abstract

The Upper Precambrian plateau lavas of the Lake Superior region were produced in response to tensional rifting of North America roughly 12001120 x 106 years ago (White, 1972a). Geological and geophysical evidence shows that they consist of a group of about eight separate volcanic accumulations which partly overlap in time and space as the locus and activity of rifting changed along what is now the Midcontinent Gravity High (Green, 1977). Nearly all of these lava accumulations ("plateaus") contain preserved sections which range in thickness from 2.5 to 7 km and are made of hundreds of individual flows. They have subsided centrally during and/or after eruption. Basalt of various compositions predominates; the most common type is nonporphyritic olivine tholeiite with unusually high Al content and ophitic texture. Transitional to weakly alkaline basalt is also common. Quartz tholeiite, basaltic andesite and rhyolite are moderately abundant in most of the plateaus, and icelandite (intermediate quartz latite) is found in some.

Description

Prepared for the Annual Meeting of THE GEOLOGICAL SOCIETY OF AMERICA, NORTH-CENTRAL SECTION and THE INSTITUTE ON LAKE SUPERIOR GEOLOGY Duluth, Minnesota, 1979, 22 p.

Related to

Replaces

License

Collections

Series/Report Number

Guidebook
11

Funding information

Isbn identifier

Doi identifier

Previously Published Citation

Other identifiers

Suggested citation

Green, John C.. (1979). Guidebook 11. Field Trip Guidebook for the Keweenawan (Upper Precambrian) North Shore Volcanic Group, Minnesota. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/58966.

Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.