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Lecture 9

EESA06H3 Lecture Notes - Lecture 9: Subduction, Mantle Convection, Stromatolite


Department
Environmental Science
Course Code
EESA06H3
Professor
Nick Eyles
Lecture
9

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Lecture 9: Canada’s Geologic Journey – The Last 4 Billion Years (Part 1)
Main Themes:
Continents grow through time
North American continent has grown in 5 stages: Ga = billion of years, Ma = million of
years
1. Arctica (2.7-3 billion years ago)
2. Nena (1.8 billion years ago)
1) and 2) phases of
expansion, crust was added
3. Rodinia (1.0 billion years ago)
most of basement rocks added to
North America in Rodinia.
o , ,  → Cato Caadia “hield
→ slight diffeees uildig of it
Canadian Shield underlies US
and Greenland (used to be
part of Canada until 80 million
years ago).
Coe of the otiet
4. Pangea assembly (350 Ma): Maritime
Canada is added during Appalachians
Orogeny (formation of Appalachian
Mountains).
Added in, underlying Eastern
Canada (Atlantic Provinces)
5. Pangea breakup (less than 200 Ma):
British Columbia is added during Cordilleran Orogeny (e.g. formation of Rockies).
Added i, udelyig B.C, Yuko, Califoia…
They added around the core.
Orogeny: mountain building/event due to collision
The geology of North America has been known for 100 years but what put it together
different types of rock, age of rocks…?
Answer: Plate tectonics.
Tuzo Wilson determined this in the 70s.
Zircons:
Very small (hair thin) crystals formed by crushed rocks with fluids that flow through
them
o They are produced in magma (action of volcanoes)
o Contain unstable uranium isotopes which we can use for radiometric dating
Deay of uaiu isotope → podue lead P
find more resources at oneclass.com
find more resources at oneclass.com
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