Permian

Permian glaciation

Permian glaciation
• Global disconformity in marine sediments
• Fossils allow global correlation.

Rates of Origination and Extinction

Rates of Origination and Extinction
• Marine mass extinction most extensive, ever
• Recovery (origination) lagged, was slow compared to extinction

• During ice age, new species were adapted to seasonal climatic changes, broadly distributed in Panthallasic Ocean
• Resistant to extinction, and also speciation during the ice age

Permian glaciation

Permian glaciation
• At the end of the ice age, massive mass
extinction – again, due to climate change.
• Life is fragile!

Permian Paleogeography

Permian Paleogeography
-Pangaea nearly complete
-Ural Mountains
-Large supercontinent produces strong climate gradients
overland between temperate coastal, extreme

Interior Pangaea

Interior Pangaea

-Low moisture
-Evaporites and dunes
-Reduced carbon burial
-Led to higher atmospheric CO2
-Global warming ended glaciation

At end of ice age, two mass extinctions:

At end of ice age, two mass extinctions
1) Guadalupian; mostly marine
2) Terminal Permian extinction; affected many terrestrial animals
-Probably caused by Asian vulcanism

-By the end Permian mass extinction, 60% marine genera, 80% marine species died out
-Largest ever for a Phanerozoic mass extinction!!

Terminal Permian mass extinction killed:

Terminal Permian mass extinction killed:
-Trilobites! Oh no!
-Tabulate and rugose corals
-Ammonids, crinoids, bryozoans hang in there
-Most Therapsids killed, but not all
-Lystrosaurus survives, dominated Therapsids in Triassic; pig-like herbivore thrived in absence of predators
-terrestrial plants: gymnosperms and woody conifers mostly
died, replaced by small, non-woody lycopods
—> FORESTS DISAPPEARED

What caused the two Permian mass extinctions?

What caused the two Permian mass extinctions?
-Stagnation of deep ocean probably reflects warming of polar regions due to global warming
-Terrestrial sediments also reflect warming, drying climate
-Eruption of Siberian Traps probably caused terminal Permian warming, mass extinction

Marine extinctions: Why global ocean anoxia?

Strictly temperature-driven extinction; conodont
d18O records indicate 8 deg. C (14 deg. F!) increase;
would kill shallow-water marine (and deep) species, as
well as terrestrial

Did permain mass extinction kill all life?

It didn’t kill ALL LIFE

-90 marine animal orders that persisted, with significant anatomical, physiological, ecological diversity, and gave rise to marine life that flourished in Mesozoic

Regional geologic events of Late Paleozoic

Regional geologic events of Late Paleozoic
• Mountain building in both Western (Sonoma) and Eastern (Allegheny and Ouachita) US
• Reef formation in Western US
Alleghenian Orogeny
• Mountain building in
Eastern US
• Valley and Ridge
– Thrust faults
• Blue Ridge
– Grenville

Ouachita Mountains

Ouachita Mountains
– Westward continuation of Appalachians
– Fold and thrust belt of offshore deposits

• Ouachita Mountains
– Flysch deposits, deep black shales shoved on top of carbonates of Ordovician to Carboniferous age; offshore deformation with high rate of deposition; unusual, very deep offshore basin

Coal-bearing cyclothems

Coal-bearing cyclothems (coal measures, in Britain) accumulated in marginal marine environments in the midcontinent

• Cycles in thin coal beds that contain marine sediments
– Slight change in sea level
– Alternating transgressions and regressions

• Transgression
– Think Everglades! Large, swampy area with slowly flowing water
—> Coal swamps form over non-marine deposits during a transgression, carbonate on top