9 Late Paleozoic Flashcards
What period was the Kaskaskia II (Palliser and Exshaw formation)
Late Devonian- earliest Mississippian
What are the rock characteristics of the lower exshaw formation?
Black organic-rich shale, no fossils
What event caused minimal fossils in the lower exshaw?
The late Devonian Extinctions
What age was the late Devonian extinction? How many phases and what are their names
375-359 Ma
2 phase, Kellwasser 372 Ma and Hanenberg 359 Ma
What event did the upper exshaw formation coincide with?
The Kellwasser event
What period was the Kaskaskia II (Banff Formation and Rundle group)?
Mississippian
What kind of rocks were formed during the Mississippian? (3)
- Carbonates
- Mud w/ local sand and lime from slope-rise
- Terranes including arcs
Slides 39-46
What is a backarc basin?
Is when there is a backarc extension caused by a convergent oceanic-continental boundary. the backarc fills in with water to create a basin
What period is the Absaroka I (spray lakes and Ishbell groups)?
Pennsylvanian to Permian
What kind of rocks are in the spray lakes and Ishbell groups?
Coarse clastics
What is the Pennsylvanian-Early Permian Cycles?
~400,000 years of episodic glacial buildup and glacial flaw producing a distinctive cyclic pattern
What is Milankovitch cyclicity?
orbital forces which caused the glacial advances and retreat
Where can you see the Milankovitch cyclicity? (2)
- Artic Canada (Nansen Formation)
- Western Canada (Johnston Canyon Formation)
What is different about the middle and late Permian rocks?
Still biogenic but they are composed of chert (SiO^2) instead of carbonates
