The Bedrock Geology of a Portion of the Cramer 15' Quadrangle, Lake County, Minnesota
1980-01
Title
The Bedrock Geology of a Portion of the Cramer 15' Quadrangle, Lake County, Minnesota
Authors
Published Date
1980-01
Publisher
Type
Thesis or Dissertation
Abstract
The area studied consists of sections 20 - 29 and 32 - 36 of T60N, R6W of the Cramer, Minnesota 15' quadrangle. Units exposed include the anorthositic "series," troctolitic "series," and felsic "series" of the Duluth Complex, volcanic rocks of the North Shore Volcanic Group, melagabbroic-gabbroic intrusive rocks, diabasic rocks, and a hypabysal intrusive. Bedrock units are locally covered by a variety of glacial deposits related to the Rainy Glacial Lobe of the Wisconsin Ice Age. Troctolites and gabbros of the troctolitic series of the Duluth Complex display cummulate textures and regular cryptic (chemical) variation in the anorthite content of plagioclase (An78 to An58), the forsterite content of olivine (Fo70 to Fo50), and in the FeO/FeO+MgO ratio in augite (22 - 40). Orientations of igneous laminations as well as the areal distribution of rock types and cryptic variations strongly suggest the troctolitic series is a sill-like intrusion which differentiated in place as the result of crystal settling.
Description
A Thesis submitted to the faculty of the Graduate School of the University of Minnesota by George Albert Lehman in partial fulfillment of the requirements for the degree of Master of Science, January 1980. Plates 1 and 2 referenced in the thesis are also attached to this record, along with the Plate 1 Key.
Related to
Replaces
License
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
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.