Permian

Permian
Scotese, Christopher R.; Vérard, Christian; Burgener, Landon; Elling, Reece P.; · CC BY 4.0 · source
Name	Permian
Color	Permian
Top gssp	Meishan, Zhejiang, China
Top gssp acceptance	2001
Base gssp	Aidaralash, Ural Mountains, Kazakhstan
Base gssp acceptance	1996
Time scale	ICS
Period	Permian
Celestial body	earth
Used by	ICS
Previous	Carboniferous
Next	Triassic

Permian. The Permian is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 251.902 million years ago. It is the last period of the Paleozoic Era, following the Carboniferous and preceding the Triassic of the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison after extensive expeditions to the region around Perm Krai in Russia.

Etymology and history

The period is named after the region of Perm Krai in the Ural Mountains of Russia, where rocks from this age were first identified and studied. The term was formally proposed by Sir Roderick Murchison in 1841 following his collaborative work with Russian geologists. Murchison's findings were detailed in his seminal work, *The Geology of Russia in Europe and the Ural Mountains*, co-authored with Édouard de Verneuil and Count Alexander von Keyserling. The International Commission on Stratigraphy later ratified the formal boundaries, with the base defined at the Aidaralash section in Kazakhstan and the top at the Meishan, Zhejiang section in China.

Geology

The Permian is subdivided into three epochs: the Cisuralian, Guadalupian, and Lopingian. These are further divided into stages such as the Asselian, Sakmarian, Artinskian, and Kungurian. The base of the Permian System is defined by the first appearance of the conodont Streptognathodus isolatus within the lineage of Streptognathodus wabaunsensis. The top is marked by the first appearance of the conodont Hindeodus parvus and coincides with a major negative excursion in δ¹³C values. Key stratigraphic sections, or Global Boundary Stratotype Section and Point locations, are found at Aidaralash and Meishan, Zhejiang.

Paleogeography and climate

During the Permian, the supercontinent Pangaea was fully assembled, stretching from pole to pole and surrounded by the global ocean Panthalassa. A large embayment called the Tethys Ocean lay on the eastern side. The formation of Pangaea created vast interior deserts, evidenced by extensive deposits of red beds and evaporites like those in the New Red Sandstone of Europe and the Rotliegend of Germany. Climates were generally warm and arid, with pronounced latitudinal gradients and evidence of glaciation in the southern regions of Gondwana, such as deposits in India, Australia, and Antarctica.

Life

Terrestrial ecosystems were dominated by diverse synapsids, including early herbivores like Edaphosaurus and dominant predators such as Dimetrodon. The late Permian saw the rise of therapsids, including dicynodonts and gorgonopsians. Flora was characterized by glossopterids in the south and conifers, cycads, and ginkgoes in the north. Marine environments featured prolific brachiopods, ammonoids, bryozoans, and crinoids. Reef builders shifted from Carboniferous rugose corals and stromatoporoids to communities dominated by sponges and algae, such as those in the Capitan Reef of the Guadalupe Mountains.

Extinction event

The end of the period is marked by the Permian–Triassic extinction event, the most severe mass extinction in Earth's history, with approximately 81% of marine species and 70% of terrestrial vertebrate families becoming extinct. Proposed causes include massive Siberian Traps flood basalt volcanism, which may have triggered global warming, ocean anoxia, and acid rain. Evidence from the Meishan, Zhejiang section shows a sharp negative δ¹³C excursion and spikes in iridium and fullerenes, supporting a catastrophic scenario. This event profoundly reset the course of evolution, paving the way for Mesozoic faunas dominated by archosaurs and eventually dinosaurs.

See also

* Geologic time scale * Paleozoic * Mass extinction * Pangaea * Therapsid * Siberian Traps

Category:Geological periods Category:Paleozoic