Permian triassic boundary by priyansh dwivedi

This presentation will be covering the topics of Permian triassic boundary, and the mass extinction that occurred in Permian.

1. Presentation by: Priyansh Dwivedi M.Sc. Final Permian-triassic boundary Government Science College Jabalpur Session 2020-21

2. Contents Introduction P-Tr boundary in Gondwana Supergroup Paleoclimate & paleoenvironment of Permian period Mass Extinction P-Tr mass extinction (Great Dying) Theories About Causes Reference

3. Time interval Permian: 298.9Ma to 251.902Ma Triassic: 251.902Ma to 201.3Ma Boundary at 251.9Ma(Induan age) The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031 Ma ago, a duration of 60 ± 48 ka

4. introduction Demarcating the Permian-Triassic boundary is beset with problems due to incomplete stratigraphic records that is attributed to the widespread regression at the close of Paleozoic era In many parts of the world, the top of the Permian succession is characterized by the presence of red beds or a phase of non-deposition( Hiatus) A fairly continuous succession of Rock formations containing Permian and Triassic faunal assemblages have been observed in many parts of India

5. The boundary delineation by faunal criterion depends on the development and availability of a continuous marine section, where the biological events established in relation to the boundary can be examined and traced Fossil fauna of the lowermost Triassic rocks is markedly different from those of the uppermost Permian GSSP of P/T boundary is placed at the first occurrence of conodont species Hindeodus parvus , which is transitional between Hindeodus and Isarcicella

6. Golden spike- 31.0798°N 119.7058°E Meishan, Southeast China The change of rock type (limestone to marl) and biostratigraphic boundary are separated by less than 0.3 m

7. These are some of the places of Hindeodus parvus zone - Meishan of Zhejiang, Guryul Ravine of Kashmir, Shangsi of Sichuan, and Selong of Tibet,etc Until 1984, the ammonoid Otoceras ( O.woodwardi ) was considered as the index fossil of the Permian-Triassic boundary (PTB). In 1986, Hindeodus parvus was proposed to substitute Otoceras as the boundary marker.

8. Conodonts  (Greek kōnos, "cone", + odont, "tooth") are extinct agnathan (jawless) chordates resembling eels, classified in the class Conodonta Conodonts such as Hindeodus are typically small, elongate, marine animals that look similar to eels today The suffix –odus typically describe’s the animal’s teeth, essentially making Hindeodus mean Hinde-teeth Hindeodus parvus

9. Conodontist have favoured the boundary above the O toceras woodwardi zone The base of Otoceras zone is apparently the level at which a maximum change in biota is recorded and is it traceable through out t he Himalaya . The P-Tr boundary palynomorphs show s an evolutionary shift and not a mass extinction Otoceras zone

10. The Guryul ravine of Vihi district in Kashmir provides one of the best known sections where the P/T boundary is defined both on faunal and lithological characteristic It has an excellent development of lower Triassic The succesion consists of an arenaceous sequence grading upward through the argillaceous rocks into a carbonate sequence The lower part of the transitional facies of argillaceous rocks(black shales) has yielded a mixed Faunal assemblage comprising productids of permian age in association with the lower Triassic bivalve Claria The boundary suggested at the base of black shales Indian example of P-Tr boundary

11. PT boundary in Gondwana supergroup The Upper Raniganj strata are floristically represented by Glossopteris , whereas the overlying panchet contains Dicroidium and, thus, there is a distinct floral change Also,based on the occurrence of Estheriids (small group of crustaceans) in the Panchet formation of Raniganj The Permo-Triassic boundary in the Raniganj basin has been suggested astride the Raniganj-Panchet boundary Furthermore, suggestions have been made for considering the Raniganj basin as the type area and Banspetali nala section as the first continental stratotype for the Permo-Triassic boundary in India{Proposed by Geological Survey of India}

12. Paleoclimate of Permian By the early permian the two great continents of paleozoic, Gondwana and Laurasia, head collided to form the supercontinent pangea The Pangea presented severe extremes of climate and environment due to its vast size The lush swamp forests of carboniferous were gradually replaced by conifers, seed ferns and other drought resistant plants The South was cold and arid with much of the region frozen under ice cap Norther n areas suffered increasingly from intense heat and great seasonal fluctuations between wet and dry conditions

13. Paleoenvironment of Permian A large (approximately 0.9%), abrupt global decrease in the ratio of the stable isotope C13 to that of C12, coincides with this extinction, and is sometimes used to identify the Permian–Triassic boundary in rocks that are unsuitable for radiometric dating Further evidence for environmental change around the P–Tr boundary suggests an 8 °C (14 °F) rise in temperature, and an increase in CO2 levels by 2000 ppm {for comparison, the amount today is about 410 ppm} There is also evidence of increased ultraviolet radiation reaching the earth, causing the mutation of plant spores ( https://www.co2.earth/daily-co2 )

14. Mass extinction Mass extinction  or  Biotic crisis is a widespread and rapid decrease in the biodiversity on earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms 

15. The Permian-Triassic Mass Extinction The Permian-Triassic extinction also known as the "Great dying", formed the boundary between the Permian & Triassic geologic periods,as well as between the Paleozoic and Mesozoic eras(~250 mya) It is the severe known extinction event,with up to 96% of all marine species & 70% of terrestrial vertebrae species becoming extinct It was the largest known mass extinction of insects There is evidence for 1-3 distinct phases of extinction. The recovery period is estimated between 2-10 million years in different study areas Many taxa slowly died out in the beginning, towards the end extinctions were more rapid

16. Boundary sections in South China show that 280 out of 329 marine invertebrate genera disappear within the final 2 conodont zones of the Permian In boundary sections preserving a record of the P-Tr transition, large numbers of species disappear over few meters of sediment or less When?

17. Systematic collections show that ~50% of families, and perhaps as much as 90% of all species known from the late Permian disappear from the fossil record during the latest Permian Killed about 95% species in oceans Marine invertebrates were hit the worst by extinction How big?

18. All trilobites 94% Graptolites All Blastoids, Acanthodians, Rugose and Tabulate Corals, Pelycosaurs 98% Crinozoans 96% Anthozoans 96% Brachiopod genera What died?

19. 85% Gastropods 59% Bivalves 79% Bryozoans 90% Gastropod genera and 3 of 16 Gastropod families 97% Ammonoids What else died?

20. Ammonoid Trilobite Blastoid Brachiopod

21. There is enough evidence to indicate that over two thirds of terrestrial labyrinthodont amphibians, sauropsid ("reptile") and therapsid ("proto-mammal") families became extinct, Large herbivores suffered the heaviest losses The groups that survived suffered extremely heavy losses of species, and some terrestrial vertebrate groups very nearly became extinct at the end of the Permian. Some of the surviving groups did not persist for long past this period, but others that barely survived went on to produce diverse and long-lasting lineages However, it took 30 million years for the terrestrial vertebrate fauna to fully recover both numerically and ecologically Vertebrates that died

22. Pelycosaurs

23. Vascular plants showed no major drop or change in numbers The fossil record shows a gradual transition from Paleozoic to Mesozoic floras Took place over a period of about 25 million years At the P–Tr boundary, the dominant floral groups changed, with many groups of land plants entering abrupt decline, such as Cordaites (gymnosperms) and Glossopteris (seed ferns) Vascular plants

24. Theories about cause The exact cause of the Permian-Triassic extinction event is difficult, mostly because it occurred 250mya, since then much of the evidence has been destroyed or is concealed deep within the layers of rocks The seafloor is also completely recycled every 200million years (plate tectonics & seafloor spreading) Scientist have proposed both catastrophic and gradual processes as the cause for this extinction Catastrophic : Impact events, Volcanism, sudden release of methane from seafloor Gradual : Sea level change, increasing anoxia, increasing aridity

25. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly, consistent with a catastrophic, possibly extraterrestrial, cause. There is some evidence supporting this theory Nickel-rich Laye from impact or heavy-metal rich mantle-derived lavas Ra re grains of  shocked quartz  in Australia and Antarctica; fullerenes  trapping extraterrestrial noble gases(He,Ar); meteorite fragments in Antarctica; and grains rich in iron, nickel, and silicon, which may have been created by an impact Impact

26. Siberian traps(flood basalts)one of the largest know volcanic events on earth & covered 2,000,000 sqkm with lava at end of Permian The Siberian Traps has climate altering potential by the emission of ash and gases Initially sulfur aerosols and volcanic ash block out sunlight, causing rapid cooling Ash and sulfur aerosols can remain in the upper atmosphere for 100’s to 1000’s of years which would be enough to cause a significant glaciation At the end of the Permian period the biggest ever drop in sea level in history occurred, indicating large scale glaciation Volcanism

27. Greenhouse gases warm the climate by allowing sunlight to pass through Heat reflected by the Earth itself cannot penetrate the atmosphere so is retained Greenhouse gases stay in the atmosphere much longer so their climate changing effects can last for millions of years

28. Evidence for widespread ocean anoxia(severe deficiency of oxygen) and euxinia(presence of hydrogen sulfide) is found from the Late Permian to Early Triassic Throughout most of the Tethys and Panthalassic Oceans, evidence for anoxia, including fine laminations in sediments, small pyrite framboids, high uranium/thorium ratios, and biomarkers for green sulfur bacteria, appear at the extinction event This spread of toxic, oxygen-depleted water would have devastated marine life, causing widespread die-offs The persistence of anoxia through the Early Triassic may explain the slow recovery of marine life after the extinction Anoxia

29. In the mid Permian Earth’s major continental plates joined, forming supercontinent called Pangea, surrounded by superocean Panthalassa Oceanic circulation and atmospheric weather patterns during mid permian produced seasonal monsoons near the coasts and an arid climate in the vast continental interior As the supercontinent formed, the ecologically diverse and productive coastal areas shrank. The shallow aquatic environments were eliminated and exposed formerly protected organisms of the rich continental shelves to increased environmental volatility Pangea

30. Pangea's formations depleted the marine life at near catastrophic rates However, Pangea's effect on land extinctions is thought to have been smaller. In fact, the advance of the therapsids and increase in their diversity is attributed to the late Permian, when Pangea's global effect was thought to have peaked While Pangea's formation certainly initiated a long period of marine extinction, its impact on the "Great Dying" and the end of the Permian is uncertain

31. Possible causes supported by strong evidence appear to describe a sequence of catastrophes, each worse than the last: the Siberian Traps eruptions were bad enough alone, but because they occurred near coal beds and the continental shelf, they also triggered very large releases of carbon dioxide and methane The resultant global warming may have caused perhaps the most severe anoxic event in the oceans' history: according to this theory, the oceans became so anoxic, anaerobic sulfur-reducing organisms dominated the chemistry of the oceans and caused massive emissions of toxic hydrogen sulfide Combinations of Causes

32. Reference Geology of India Vol. 2 by Vaidyanadhan & Ramakrishnan Historical Geology & Stratigraphy of India by Ravindra kumar https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event https://www.researchgate.net/publication/266021556_Study_of_Permo - Triassic_boundary_in_Gondwana_sequence_of_Raniganj_basin_India https://www.co2.earth/daily-co2 Images from Google

33. Thank you