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Earth History GEOL 2110

Earth History GEOL 2110. The Cryptozoic (Precambrian) SuperEon Part 3: The Meso - and Neoproterozoic Eras. Major Concepts. After the formation of the Paleoproterzoic continent of Laurentia , new marginal terranes continued to be added to the “south” in the Mesoproterzoic .

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Earth History GEOL 2110

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  1. Earth History GEOL 2110 The Cryptozoic (Precambrian) SuperEon Part 3: The Meso- and Neoproterozoic Eras

  2. Major Concepts • After the formation of the Paleoproterzoic continent of Laurentia, new marginal terranes continued to be added to the “south” in the Mesoproterzoic. • The most significant of these terranes was the Grenville which was a mobile belt formed by the collision of Amazonia and Laurentia between 1.2 and 0.9 Ga • A major starting plume event at 1.1 Ga impacted the lithosphere under what would become Lake Superior. This brought on the development of the Midcontinent Rift – an aborted attempt at continental rifting. • Toward the end of the Proterozoic Eon (~1.0 Ga), one of the largest supercontinents in earth history formed, Rodinia, which had Laurentia at its core.

  3. PALEOPROTEROZOIC ACCRETED TERRANES Creation and Growth of LAURENTIA

  4. _______________ THE MIDCONTINENT RIFT _______________ An attempt at continental rifting 1.1 billion years ago

  5. The Evolution of the Midcontinent Rift 1,109-1,086 Ma 1,090-900 Ma 1,000-900 Ma

  6. Fissure Eruption

  7. Massive Basalt Amygdaloidal Basalt

  8. Amygdules – Gas bubble fillings Chlorite & Zeolite Zeolite Epidote & Feldspar Thompsonite

  9. LAKE SUPERIOR AGATES Gemstone of Minnesota

  10. Formation of Lake Superior Agates

  11. BASALT FLOW SURFACES AA AA Pahoehoe HAWAII Pahoehoe NORTH SHORE

  12. High Falls on the Baptism River Palisade Head Rhyolite RHYOLITE The other volcanic rock type Palisade Head

  13. INTRUSIVE IGNEOUS ROCKS Gabbro Magmas trapped in the Crust Duluth Complex Layered Gabbro Beaver Bay Complex Granite

  14. Origin of MCR Igneous Rocks

  15. SEDIMENTARY ROCKS of the Midcontinent Rift Cutface Creek Sandstone Freda Sandstone

  16. LATE-STAGE FAULTING The Douglas Fault at Amnicon Falls State Park Basalt Fault Sandstone

  17. Why isn’t Duluth a Sea-side Resort? Blame it on Grenville & Rodinia

  18. Assembly of Rodinia 1200 – 750 Ma Li et al., 2008

  19. Li et al., 2008

  20. Deconstruction ofRodinia by a Superplume 750 Ma Li et al., 2008

  21. Next Lecture Early Evolution of Life Chapter 9 Midterm I returned –PROMISE!

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