with laminations or varves: fine laminations indicating seasonal Mudstones deposition in adjacent to ice sheets. dropstones (dropped from melting icebergs) in varved sedimentary rocks. Glacial or glacial diamictites (poorly sorted conglomerates of glacial debris). Tillites and faceted cobbles and boulders in tillite, due to abrasion as ice Scratched moved. WIDESPREAD GLACIATION of global glaciations = 2.6–2.1 b.y. ago (2600–2100 m.y.). Age glaciation at this time as indicated by glacial deposits in: Widespread Europe Africa Southern India BANDED IRON FORMATIONS AND PROKARYOTE FOSSILS Extensive banded iron formations (BIF's) on the western shores of Lake Superior, indicate that photosynthesis was occurring and oxygen was being produced. BANDED IRON FORMATIONS AND PROKARYOTE FOSSILS  BIF deposits are >1000 m thick, and extend over 100 km. Some Gunflint Chert, within the BIF sequence, contains fossil remains of prokaryotic The organisms, including cyanobacteria. Age = 1.9 b.y. LABRADOR TROUGH of the Superior province are rocks deposited on a continental shelf, slope, and East rise. are similar to those of the Wopmay orogenic belt. Rocks rocks were folded, metamorphosed, and thrust-faulted during the Hudsonian These orogeny, which separates the Paleoproterozoic from the Mesoproterozoic. HIGHLIGHTS OF THE MESOPROTEROZOIC Mesoproterozoic (or middle Proterozoic) ranges from about 1.6 b.y.–1.0 b.y. The Midcontinent rift, an abandoned oceanic rift in the Lake Superior region with The massive basaltic lava flows mineralization in the Lake Superior region Copper collisions producing the Grenville orogeny in eastern North America Continental assembly of continents to form the supercontinent, Rodinia. The MIDCONTINENT RIFT AND THE KEWEENAWAN SEQUENCE rift extends southward from Lake Superior region. Midcontinent Archean crystalline basement rocks and Paleoproterozoic Animikian Overlies MIDCONTINENT RIFT AND THE KEWEENAWAN SEQUENCE volumes of basaltic rock indicate presence of an abandoned rift zone called Large the Midcontinent rift. was the stage of a Wilson Cycle. This
Mudstones with laminations or varves: fine laminations indicating seasonal deposition in adjacent to ice sheets. Glacial dropstones (dropped from melting icebergs) in varved sedimentary rocks. Tillites or glacial diamictites (poorly sorted conglomerates of glacial debris). Scratched and faceted cobbles and boulders in tillite, due to abrasion as ice moved. WIDESPREAD GLACIATION Age of global glaciations = 2.6–2.1 b.y. ago (2600–2100 m.y.). Widespread glaciation at this time as indicated by glacial deposits in: Europe Southern Africa India BANDED IRON FORMATIONS AND PROKARYOTE FOSSILS Extensive banded iron formations (BIF's) on the western shores of Lake Superior, indicate that photosynthesis was occurring and oxygen was being produced. BANDED IRON FORMATIONS AND PROKARYOTE FOSSILS  Some BIF deposits are >1000 m thick, and extend over 100 km. The Gunflint Chert, within the BIF sequence, contains fossil remains of prokaryotic organisms, including cyanobacteria. Age = 1.9 b.y. LABRADOR TROUGH East of the Superior province are rocks deposited on a continental shelf, slope, and rise. Rocks are similar to those of the Wopmay orogenic belt. These rocks were folded, metamorphosed, and thrust-faulted during the Hudsonian orogeny, which separates the Paleoproterozoic from the Mesoproterozoic. HIGHLIGHTS OF THE MESOPROTEROZOIC The Mesoproterozoic (or middle Proterozoic) ranges from about 1.6 b.y.–1.0 b.y. The Midcontinent rift, an abandoned oceanic rift in the Lake Superior region with massive basaltic lava flows Copper mineralization in the Lake Superior region Continental collisions producing the Grenville orogeny in eastern North America The assembly of continents to form the supercontinent, Rodinia. MIDCONTINENT RIFT AND THE KEWEENAWAN SEQUENCE Midcontinent rift extends southward from Lake Superior region. Overlies Archean crystalline basement rocks and Paleoproterozoic Animikian MIDCONTINENT RIFT AND THE KEWEENAWAN SEQUENCE Large volumes of basaltic rock indicate presence of an abandoned rift zone called the Midcontinent rift. This was the stage of a Wilson Cycle.
Ch09%20The%20Proterozoic%20Dawn%20of%20a%20more%20modern%20World%20Notes.docx