Earth History GEOL 2110 The Cryptozoic (Precambrian) SuperEon Part 2: The Paleoproterozoic Era Major Concepts • After the formation of the Archean continental landmass (Kenoraland), Minnesota.
Download ReportTranscript Earth History GEOL 2110 The Cryptozoic (Precambrian) SuperEon Part 2: The Paleoproterozoic Era Major Concepts • After the formation of the Archean continental landmass (Kenoraland), Minnesota.
Earth History GEOL 2110 The Cryptozoic (Precambrian) SuperEon Part 2: The Paleoproterozoic Era Major Concepts • After the formation of the Archean continental landmass (Kenoraland), Minnesota lay at a passive margin where sedimentary rocks accumulated including Snowball Earth tillites and the great Lake Superior banded iron formations. • These sedimentary rocks were deformed ~1.85 Ga by the collision of volcanic arc terrane with Kenoraland, an event called the Penokean orogeny. This event sutured several Archean terrains together to form a larger continent called Laurentia. • Laurentia continued grow in the Paleoproterozic by adding more terrains to the south at 1.7Ga (Yavapi orogen) and 1.6Ga (Mazatzal orogen). Today’s Lecture Kenoraland Paleoproterozoic Rocks of Minnesota Sedimentary rock accumulated in the Animikie Sea then deformed in the Penokean Orogeny Creating the Animikie Basin by Continental Rifting Paleoproterozoic Sedimentary Rocks of the Lake Superior Region Animikie Group Menominee Group Huronian Supergroup Archean Huronian Supergroup Sedimentary Rocks TILLITES U-bearing Matinenda Fm Ramsey Lake Fm Carbonates of the Espanola Fm Gowganda Fm Bruce Fm Limestone Tillite Paul Hoffman MESABI-TYPE IRON FORMATION Geologic Marker of a Major Evolutionary Event STROMATOLITES (Fossilized Algal Mats) Evidence of Early Life The 1.85 Ga Sudbury Impact The First Major Extinction Event ?? Hibbing, MN Ishpeming, MI Paleoproterozoic Iron Ranges of the Lake Superior Region Rocheleau Pit Dunka Pit Peter Mitchell Pit Progressive Deformation across the Penokean Orogen Eveleth – Flat-lying Biwabik Fe-Fm Jay Cooke Park – Deformed Thomson Fm St. Cloud – Granite intrusions St. Cloud Eveleth Jay Cooke Continental Shelf Suture –Niagara Fault Volcanic Arc DENUDATION OF A MOUNTAIN BELT SIOUX QUARTZITE ~1.7 Ga Mature Sandstone Flambeau Blue Mounds State Park Rib Mtn Sioux Baraboo Pipestone National Monument More Paleoproterzoic Mountain-building Events Yavapai Orogeny: 1770-1730 Ma Mazatzal Orogeny: 1650-1600 Ma Holm et al., 2007 Summary of Paleoproterozoic Tectonic Events in the Upper Midwest Holm et al., 2007 PALEOPROTEROZOIC ACCRETED TERRANES Creation and Growth of LAURENTIA Next Lecture The Final Chapter of the Precambrian The Meso- and NeoProterozoic