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New model of the midcontinent rift in eastern Minnesota and western Wisconsin
Author(s) -
McSwiggen Peter L.,
Morey G. B.,
Chandler Val W.
Publication year - 1987
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/tc006i006p00677
Subject(s) - geology , rift , graben , volcano , mafic , clastic rock , volcanic rock , sedimentary rock , rift valley , rift zone , geomorphology , geochemistry , igneous rock , block (permutation group theory) , paleontology , structural basin , geometry , mathematics
The Midcontinent rift contains a central zone of mostly volcanic and associated intrusive rocks. Flanking, and in places overlying, these mafic igneous rocks are clastic sedimentary basins which range in thickness from less than 1.5 km southwest of the west end of Lake Superior to more than 3.0 km near the Minnesota‐Iowa border. New gravity and magnetic modeling of the rift has shown that most of the volcanic and intrusive rocks are contained within a central block, which in Minnesota and Wisconsin extends to a depth of at least 10 to 20 km. The geometry of this central block, which ranges from fairly symmetric to very asymmetric, appears to reflect a change from predominantly a graben to only a half‐graben development. The modeling has also suggested the presence of a major prerift intrusive body along the Minnesota‐Iowa border which could have locally controlled the rift’s development.