Paleogeography and Geology of the Permian:
Increase in continental climates (extreme summers and winters, arid conditions) in many parts of the world, as Pangaea becomes more emergent.

In restricted basins, major evaporite deposits. Elsewhere, lots of eolian deposits.

CO₂ levels begin to rise:

• Drier conditions cause major decline in the coal swamps, so less carbon is buried
• Drier conditions also means less chemical weathering
• Gondwanan glaciers shrink somewhat

Collision between Siberia and northeastern Pangaea (former eastern part of Laurussia); Uralian Orogeny (Permian)

The Chinese blocks remain the only large cratons not attached to Pangaea.

Latest Permian and earliest Triassic:

• Collision between microplate Sonomia and western Laurentian part of Pangaea
• Sonoman Orogeny: part of the Cordilleran orogenies
• Sonomia is now southeastern Oregon, northern California, and northern Nevada
• The accretionary wedge formed during the orogeny is called the Golcanda terrane

Downwarped basins in what is now west Texas were bordered by big reef complexes (sponges, bryozoans, algae, brachiopds are main reef formers); otherwise, very few reefs from the Permian.

At very end (last half million years?) of Permian: Siberian Traps:

• Largest flood basalt & largest volcanic episode in all of the Phanerozoic
• Up to 3 million km³ of lava: if spread across whole of Earth's surface, would be a basalt layer 3 m thick!!
• Coincides with the Permo-Triassic extinction, the largest of the Phanerozoic

To Next Lecture.
To Previous Lecture.
To Syllabus.

Last modified: 10 January 2008