Post-tectonic mafic intrusions (MNAmi;0)

Post-tectonic mafic intrusions - Gabbro, peridotite, pyroxenite, and their metamorphic equivalents. Unit also includes small intrusive complexes of anorthosite, gabbroic anorthosite, and anorthositic gabbro. Generally characterized by pronounced magnetic signatures.

State	Minnesota
Name	Post-tectonic mafic intrusions
Geologic age	Late Archean
Original map label	Ami
Primary rock type	gabbro
Secondary rock type	peridotite
Other rock types	pyroxenite; anorthosite
Lithologic constituents	Major Igneous > Plutonic > Gabbroic > Gabbro Igneous > Plutonic > Ultramafic > Pyroxenite Igneous > Plutonic > Ultramafic > Peridotite Minor Igneous > Plutonic > Anorthosite
Map references	Morey, G.B., and Meints, Joyce, 2000, Geologic map of Minnesota - Bedrock Geology: Minnesota Geological Survey, State Map Series, S-20, 3rd edition, scale 1:1,000,000. available online at: http://www.geo.umn.edu/mgs/currentpubs.htm [http://www.geo.umn.edu/mgs/currentpubs.htm]
Unit references	Morey, G.B., and Meints, Joyce, 2000, Geologic map of Minnesota - Bedrock Geology: Minnesota Geological Survey, State Map Series, S-20, 3rd edition, scale 1:1,000,000. available online at: http://www.geo.umn.edu/mgs/currentpubs.htm [http://www.geo.umn.edu/mgs/currentpubs.htm]
Geographic coverage	Beltrami - Clay - Clearwater - Kittson - Koochiching - Lake of the Woods - Marshall - Norman - Pennington - Polk - Red Lake - Roseau