Proterozoic Geology Flashcards
What process marks the beginning of the Proterozoic eon?
The beginning of modern plate tectonics.
How long was the Proterozoic eon?
2 billion years
How was the atmosphere different in the Proterozoic from earlier eons?
It was oxygenated
The continent Laurentia is made of modern day
Greenland and North America
Subdivisions of Proterozoic Eon
–Beginnings of ‘modern’ tectonics
–Oxygenation of the atmosphere
–First major global glaciations
–Evolution of multicellular life
When did the first multicellular life evolve?
1.2 billion years ago
What is special about ediacaran fauna
preservation, structure
Proterozoic life/fossils is made up mostly of
soft bodied organisms and trace fossils
common Proterozoic life
stromatolites, algae, microbial mats…. covered most underwater substrates
Kenorland lasted from
2.7 - 2.1 Ga
Kenorland formed when?
End of Archean
Huronian Glaciation
First major glacial episode corresponds to Kenorland supercontinent stage
Laurentia corresponds to
North American craton
Sandstone - shale - carbonate assemblages are characteristic of
passive margins
Supercontinent Columbia existed during what time period
1.8 - 1.6 Ga
What is significant about the Grenville orogeny?
It involved the formation of the supercontinent Rodinia.
When did the Grenville orogeny occur?
1.3 - .9 Ga
When did Supercontinent Rodinia exist?
1.1 - .75 Ga
What was significant about Rodinia?
first real supercontinent - all major cratons were involved
When did the cryogenian glaciation occur?
800 - 635 Ma
What significant climatic period occurred during the cryogenian?
Snowball earth - glaciers extended to equator
What caused the “snowball earth” phase?
runaway icehouse, continental distribution, high oxygen/low CO2
When did Supercontinent Pannotia exist?
600 - 540 Ma
Why was Pannotia significant
formation of Phanerozoic continents
When did the great Oxygenation event occur
approximately 2.4 billion years ago
What is evidence for the increase of oxygenation in the atmosphere?
banded iron formations
occurred typically in silica rich sediments - chert
