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Geologic Map Series 1. Bedrock Geology of Duluth and Vicinity St. Louis County, Minnesota
Taylor, Richard B. (Minnesota Geological Survey, 1963)
 

Title 
Geologic Map Series 1. Bedrock Geology of Duluth and Vicinity St. Louis County, Minnesota

Author(s)

Issue Date
1963

Publisher
Minnesota Geological Survey

Type
Report

Abstract
Duluth, Minnesota, is on the northwest limb of the Lake Superior syncline, a northeast-trending structure of Precambrian age. The north- west limb of the syncline dips 10-20 degrees S.E. toward Lake Superior and is dominated by the Duluth Gabbro Complex, a huge sill-like mass with crescentic outcrop that extends almost 150 miles from Duluth to near Hovland. At Duluth the gabbro complex lies on the Thomson Formation, and apparently was intruded along the surface of unconformity below the Keweenawan rocks. The gabbro complex was formed by multiple intrusion, and consists of an older anorthositic gabbro and a younger layered gabbro and related intrusions. Keweenawan flows above the gabbro mass are cut by diabase sills. The basalt flows at one locality currently are being quarried as a source of crushed rock for concrete aggregate.

Appears in Collection(s)

Series/Report Number
Geologic Map Series
1

Description
Text 12 p., 1 map plate. Scale 1:24,000.

Suggested Citation
Taylor, Richard B.. (1963). Geologic Map Series 1. Bedrock Geology of Duluth and Vicinity St. Louis County, Minnesota. Minnesota Geological Survey. Retrieved from the University of Minnesota Digital Conservancy, http://purl.umn.edu/57303.


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