Permian

Permian
source
Name	Permian
Time start	298.9 million years ago
Time end	251.902 million years ago
Period	Permian
Preceding period	Carboniferous
Following period	Triassic

Permian The Permian was the last period of the Paleozoic Era, marking a pivotal interval between the Carboniferous and the Mesozoic Eras. It witnessed major reorganizations of paleogeography, pronounced shifts in climate and sea-level, and culminated in the most severe mass extinction in Earth's history, which reshaped trajectories for vertebrate and invertebrate lineages worldwide.

Definition and Temporal Boundaries

The period is formally bounded by the uppermost boundary of the Carboniferous and the base of the Triassic, with its onset near 298.9 Ma and termination at about 251.9 Ma as defined by the International Commission on Stratigraphy chronostratigraphic framework. Global stratotypes and boundary stratotype sections, such as the GSSP at Golden Spike localities, were established using a combination of biostratigraphic markers—particularly conodonts like Hindeodus parvus—and radiometric calibration from volcanic ash beds correlated to U-Pb zircon ages. Biogeographic provinciality is reflected in fossil assemblages tied to paleocontinents like Pangaea, Laurasia, Gondwana, and terranes now part of Siberia, Kazakhstan, North America, Europe, and China.

Geology and Paleoenvironments

Tectonic consolidation produced the supercontinent Pangaea, influencing circulation patterns between the Panthalassa ocean and the Tethys Sea. Continental interiors experienced pronounced aridification recorded in red beds, evaporites, and eolian dune deposits preserved in basins such as the Zechstein Basin, Ural Basin, and the Permian Basin (USA). Marine shelves show sequences of carbonates and siliciclastics with cyclical transgressive-regressive patterns linked to glacio-eustatic forcing and tectonism across regions like Siberian Traps margins, South China Block, and the Arabian Plate. Paleosols, coal measures in remnants of Laurentia and Baltica, and reef frameworks built by organisms including sponges and bryozoans record diverse nearshore to offshore environments.

Paleocene Biota and Evolutionary Trends

Terrestrial and marine ecosystems were dominated by a variety of vertebrates and invertebrates undergoing key evolutionary novelties. Synapsid clades such as Dimetrodon-grade pelycosaurs and therapsids including Gorgonopsia, Theriodontia, Dicynodontia, and early Cynodontia diversified alongside amphibian groups like Temnospondyli and reptiliomorphs. Marine faunas featured brachiopods, bivalves, ammonoids (e.g., Goniatites), echinoderms, and foraminifera; reef builders included sponges and calcareous algae. Plant assemblages ranged from lycophytes and sphenopsids to seed ferns and emerging gymnosperms such as Cordaites and early Coniferales, with important floras described from Gondwana localities, Cathaysian provinces, and Laurasian coal-bearing basins. Biotic turnovers show province-specific radiations and extinctions reflected in fossil sites like Karoo Basin, Marlborough, Beclayan, European Permian basins, and Chinese terrestrial assemblages documented in Jiaolou and Shanxi sequences.

Major Events: Glaciations, Sea-Level Changes, and the End-Permian Extinction

Glacial episodes in the late Carboniferous into the early part of the period waned, contributing to long-term sea-level rise and subsequent regressions recorded in cyclic sequences across Gondwana margins. The culmination of the period was marked by the end-Permian extinction event, temporally associated with massive volcanic outpourings in the Siberian Traps, which injected greenhouse gases, aerosols, and mercury into the atmosphere, causing rapid warming, ocean anoxia, acidification, and collapse of carbonate platforms. This crisis eliminated many marine taxa (e.g., stenotopic brachiopods, reef builders, many ammonoid families) and terrestrial groups (notably many synapsid lineages), with extinction patterns documented in sections such as the Meishan GSSP and continental records from the Karoo Basin and Zagros-adjacent basins.

Stratigraphy and Regional Correlations

Regional stage schemes—such as the Cisuralian, Guadalupian, and Lopingian series—provide subdivisions tied to type localities like the Ural Mountains, Guadalupian Basin (Texas and New Mexico), and Lopingian sections in China. Correlation integrates conodont, ammonoid, foraminiferal, and palynological zonations with magnetostratigraphy and radiometric ages from volcanic layers (e.g., U-Pb zircon data from ash beds). Important regional correlations connect the Zechstein evaporite cycles of Europe with the Guadalupian reef-carbonate platforms of North America and the extensive siliciclastic successions of the Karoo Basin; these syntheses inform basin evolution, paleoclimate reconstructions, and migration pathways for terrestrial faunas between Laurasia and Gondwana.

Economic Significance and Natural Resources

Sedimentary deposits of this interval host major hydrocarbon reservoirs, source rocks, and evaporite seals exemplified by the Permian Basin (USA), the Zechstein plays of Europe, and petroleum systems in the Middle East and Siberia. Significant coal seams in former equatorial basins fueled later industrialization in regions such as Eurasia and North America. Evaporites, potash, and salt deposits from basins like Zechstein and Soligorsk are critical for fertilizer and chemical industries, while carbonate reservoirs in Guadalupian strata contribute to oil and gas production in fields across Texas and New Mexico. Paleontological sites from this interval remain central to research institutions including the Smithsonian Institution, Natural History Museum, London, and multiple university museums that curate type specimens and stratigraphic collections.

Category:Geological periods