North Range Group; Trommald Formation (MNPRent;0)

North Range Group; Trommald Formation - Carbonate-silicate iron-formation overlain by hematite iron-formation and associated manganese oxide deposits. Also contains substantial quantities of volcanic and hypabyssal rocks of generally mafic composition. Metamorphosed to greenschist facies.

State	Minnesota
Name	North Range Group; Trommald Formation
Geologic age	Early Proterozoic
Original map label	Pent
Primary rock type	iron formation
Secondary rock type	metavolcanic rock
Other rock types
Lithologic constituents	Major Sedimentary > Chemical > Banded-iron-formationcarbonate-silicate iron-formation overlain by hematite iron-formation Minor Metamorphic > Metaigneous > Metavolcaniccarbonate-silicate iron-formation overlain by hematite iron-formation
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	Crow Wing