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

8. • 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.

9. • 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

10. • Conodontist have favoured the boundary above the Otoceras
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 the Himalaya.
• The P-Tr boundary palynomorphs shows an evolutionary
shift and not a mass extinction
Otoceras zone

11. • 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

14. 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}

15. 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
• Northern areas suffered increasingly from intense heat and great seasonal
fluctuations between wet and dry conditions

16. •

17. 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)

18. 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

19. 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

20. • 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?

21. • 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?

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

23. • 85% Gastropods
• 59% Bivalves
• 79% Bryozoans
• 90% Gastropod genera and
• 3 of 16 Gastropod families
• 97% Ammonoids
What else died?

24. AmmonoidTrilobite
Blastoid Brachiopod

25. • 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

26. Pelycosaurs

27. • 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

28. 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

29. • 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
• Rare 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

31. • 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

32. • 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

35. • 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

36. • 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

37. • 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

39. • 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

40. REFEREN
CE
• 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_extinctio
n_event
• https://www.researchgate.net/publication/266021556_Study_of_Per
mo-
Triassic_boundary_in_Gondwana_sequence_of_Raniganj_basin_In
dia
• https://www.co2.earth/daily-co2
• Images from Google

41. THANK YOU