Evidence of Extensive Mercury Pollution During Permian Triassic Mass Extinction

Isotopic signatures of mercury contamination in latest Permian oceans

Authors:

Grasby et al

Abstract:

Sedimentary records from the northwest margin of Pangea and the Tethys show anomalously high Hg levels at the latest Permian extinction boundary. Background δ202Hg values are consistent with normal marine conditions but exhibit negative shifts coincident with increased Hg concentrations. Hg isotope mass-independent fractionation (Δ199Hg) trends are consistent with volcanic input in deep-water marine environments. In contrast, nearshore environments have Δ199Hg signatures consistent with enhanced soil and/or biomass input. We hypothesize that the deep-water signature represents an overall global increase in volcanic Hg input and that this isotope signature is overwhelmed in nearshore locations due to Hg from terrestrial sources. High-productivity nearshore regions may have experienced stressed marine ecosystems due to enhanced Hg loading.

Permian Extinction NOT as Deadly as Originally Thought?

Estimates of the magnitudes of major marine mass extinctions in earth history

Author:

Stanley

Abstract:

Procedures introduced here make it possible, first, to show that background (piecemeal) extinction is recorded throughout geologic stages and substages (not all extinction has occurred suddenly at the ends of such intervals); second, to separate out background extinction from mass extinction for a major crisis in earth history; and third, to correct for clustering of extinctions when using the rarefaction method to estimate the percentage of species lost in a mass extinction. Also presented here is a method for estimating the magnitude of the Signor–Lipps effect, which is the incorrect assignment of extinctions that occurred during a crisis to an interval preceding the crisis because of the incompleteness of the fossil record. Estimates for the magnitudes of mass extinctions presented here are in most cases lower than those previously published. They indicate that only ∼81% of marine species died out in the great terminal Permian crisis, whereas levels of 90–96% have frequently been quoted in the literature. Calculations of the latter numbers were incorrectly based on combined data for the Middle and Late Permian mass extinctions. About 90 orders and more than 220 families of marine animals survived the terminal Permian crisis, and they embodied an enormous amount of morphological, physiological, and ecological diversity. Life did not nearly disappear at the end of the Permian, as has often been claimed.

Recovery From the Permian Extinction Delayed by Productivity Crises During Early Triassic

Early Triassic productivity crises delayed recovery from world's worst mass extinction

Authors:

Grasby et al

Abstract:

The recovery of life after the latest Permian extinction was protracted over Early Triassic time. Detailed geochemistry of marine sections along northwest Pangea indicates that upwelling ceased at the extinction event. Nitrogen stable isotope data suggest that this was associated with progressive increase in nutrient stress throughout the Early Triassic, coincident with a significant decrease in organic carbon content despite pervasive anoxic to euxinic conditions. We argue that the Early Triassic hothouse both reduced marine productivity and deepened the nutricline, reducing the overall rate of nutrient delivery to the photic zone, creating an Early Triassic nutrient gap. When oceans finally cooled by Middle Triassic time, renewed nutrient upwelling and onset of organic-rich shale deposition occurred across northwest Pangea, marking the final return of global marine productivity.

Iron-rich, Hyopxic Seas Might Have Helped Delay Biotic Recovery After the Permian Extinction

Scientists have shed light on why life on Earth took millions of years to recover from the greatest mass extinction of all time.

The study provides fresh insight into how Earth's oceans became starved of oxygen in the wake of the event 252 million years ago, delaying the recovery of life by five million years.

Findings from the study are helping scientists to better understand how environmental change can have disastrous consequences for life on Earth.

The Permian-Triassic Boundary extinction wiped out more than 90 per cent of marine life and around two thirds of animals living on land. During the recovery period, Earth's oceans became starved of oxygen - conditions known as anoxia.

Previous research suggested the mass extinction and delayed recovery were linked to the presence of anoxic waters that also contained high levels of harmful compounds known as sulphides.

However, researchers say anoxic conditions at the time were more complex, and that this toxic, sulphide-rich state was not present throughout all the world's oceans.

The team, led by researchers at the University of Edinburgh, used precise chemical techniques to analyse rocks unearthed in Oman that were formed in an ancient ocean around the time of the extinction.

Data from six sampling sites, spanning shallow regions to the deeper ocean, reveal that while the water was lacking in oxygen, toxic sulphide was not present. Instead, the waters were rich in iron.

The finding suggests that iron-rich, low oxygen waters were a major cause of the delayed recovery of marine life following the mass extinction.

link.

How Dominant Were Disaster Taxa After the Permian Extinction

Quantitative analysis of the ecological dominance of benthic disaster taxa in the aftermath of the end-Permian mass extinction

Authors:

Petsios et al

Abstract:

The end-Permian mass extinction, the largest extinction of the Phanerozoic, led to a severe reduction in both taxonomic richness and ecological complexity of marine communities, eventually culminating in a dramatic ecological restructuring of communities. During the Early Triassic recovery interval, disaster taxa proliferated and numerically dominated many marine benthic invertebrate assemblages. These disaster taxa include the bivalve genera Claraia, Unionites, Eumorphotis, and Promyalina, and the inarticulate brachiopod Lingularia. The exact nature and extent of their dominance remains uncertain. Here, a quantitative analysis of the dominance of these taxa within the fossil communities of Panthalassa and Tethys benthic realms is undertaken for the stages of the Early Triassic to examine temporal and regional changes in disaster-taxon dominance as recovery progresses. Community dominance and disaster-taxon abundance is markedly different between Panthalassic and Tethyan communities. In Panthalassa, community evenness is low in the Induan stage but increases significantly in the Smithian and Spathian. This is coincident with a significant decrease in the relative abundance and occurrence frequency of the disaster taxa, most notably of the low-oxygen-affinity taxa Claraia and Lingularia. While the disaster taxa are present in post-Induan assemblages, other taxa, including two articulate brachiopod genera, outrank the disaster taxa in relative abundance. In the Tethys, assemblages are generally more even than contemporaneous Panthalassic assemblages. We observe an averaged trend toward more even communities with fewer disaster taxa in both Panthalassic and Tethyan assemblages over time.

A Major Floral Extinction 500,000 Years After the Permian-Triassic Mass Extinction (Another Pulse?)

There have been several mass extinctions in the history of Earth with adverse consequences for the environment. Researchers from the University of Zurich have now uncovered another disaster that took place around 250 million years ago and completely changed the prevalent vegetation during the Lower Triassic.

There have been several mass extinctions in the history of Earth. One of the largest known disasters occurred around 252 million years ago at the boundary between the Permian and the Triassic. Almost all sea-dwelling species and two thirds of all reptiles and amphibians died out. Although there were also brief declines in diversity in the plant world, they recovered in the space of a few thousand years, which meant that similar conditions to before prevailed again.

link.

The Oceans Recovered From the Permian Mass Extinction Quickly

Reptiles rapidly invaded the seas soon after a global extinction wiped out most life on Earth, according to a new study led by University of California, Davis, researchers.

Global climate change -- likely triggered by massive volcanic eruptions -- killed off more than 95 percent of all species about 250 million years ago, at the end of the Permian period. Land reptiles colonized the ocean in just 3.35 million years at the beginning of the Triassic, a speedy recovery in geologic time, the researchers report today (June 13) in the journal Scientific Reports.

"Our results fit with the emerging view that the recovery was faster than previously thought," said study co-author Ryosuke Motani, professor of paleobiology at UC Davis' Department of Earth and Planetary Sciences.

The research was led by Wanlu Fu, now of the Laboratory of Orogenic Belt and Crustal Evolution at Peking University. Fu conducted the research while an in-residence doctoral student working with study co-author Isabel Montañez, professor of geochemistry at UC Davis. Co-authors include scientists from the University of Wisconsin and the University of Milan in Italy. The fossils and rock samples were collected from Majiashan in Chaohu, South China.

link.

Helms Deep for Metazoan Reef Builders Found From Permian Extinction era Slovenia?

Equatorial Palaeotethys as the last sanctuary for late Permian metazoan reef-builders: New evidence from the Bellerophon Formation of Slovenia

Authors:

Sremac et al

Abstract:

The rise and demise of warm-temperate Permian reefs and biostromes reflect the complex geologic history of this dynamic period. Environments suitable for reef-builders were devastated by the Guadalupian/Lopingian crisis, and Lopingian reefs have only been recorded at a small number of localities. The uppermost Permian limestones of the Bellerophon Formation, on the Vojsko Plateau (Slovenia), contain small, lenticular biostromes within a bioclastic wackestone/packstone lithofacies. The major biostrome builders are medium-sized coralline sponges (Demospongea and Calcarea), encrusted by smaller sponges, tube worms, sessile foraminifera, calcareous algae (Archaeolithoporella) and Shamovella (i.e., Tubiphytes), all of which are typically covered by microbial crusts. The biostromes are characteristically composed of bafflestone and bindstone, incorporating sporadic framestone. Narrow belts of floatstone surround the buildups, and sponge debris is also present in lenses within the mud matrix between metazoan bafflestones. The fossils are generally well-preserved, although the fine skeletal microstructure has been partially recrystallized. Sponges are heavily calcified, and ontogenic thickening of the skeleton can be observed in some encrusters. Framboidal pyrite, forming thin films on the inner walls of sponge chambers, suggests the presence of sulphate-reducing bacteria. These microbial symbionts may have enabled the sponges to survive in the anoxic marine environments of the uppermost Permian. The Changshingian sponge biostromes of the Vojsko Plateau represent the westernmost known occurrence of contemporary metazoan boundstones in the Palaeotethys.

Multiple Carbon Excursions Found Across Permian Triassic Boundary

Permian–Triassic boundary (PTB) in the Lower Yangtze Region, southeastern China: A new discovery of deep-water archive based on organic carbon isotopic and U–Pb geochronological studies

Authors:

Liao et al

Abstract:

The Lower Yangtze Region of southeastern China is an important area for the study of Permian–Triassic Boundary (PTB). In this region many well-known PTB sections (e.g., Meishan) have been investigated widely and extensively; however, these sections are dominantly in shallow-water settings and data from deep-water areas are lacking. To fill the gap, we conducted a field survey recently and found a deep-water PTB section with relatively continuous deposition using integrated organic carbon isotopic and U–Pb geochronological studies. This well-exposed and fresh section is located at Niushan, Xuancheng city, Anhui Province, ~ 90 km west of the well-known Meishan section, which is the PTB Global Boundary Stratotype Section and Point. The organic carbon isotope curve of the section contains three positive excursions (PCIEs) and two negative excursions (NCIEs), which can be well correlated with other PTB sections as well as with Wuchiapingian–Changhsingian Boundary (WCB) sections worldwide. They archive the original PTB and WCB signatures. Further U–Pb dating of magmatic zircons in volcanic ashes validates this new finding, i.e., the PTB interval between 252.49 ± 0.76 Ma and 251.74 ± 0.77 Ma. Carbon isotopes of PTB sections in South China reflect the regional paleogeography. The two NCIEs (NCIE-2 and NCIE-3) across the PTB transition are most likely caused by widespread large-scale volcanic activity. In contrast, the NCIE-1 near the WCB is possibly related to an increase in the productivity of organic matter as a result of transgression and a change in the organic matter type from terrigenous to marine.

Post Permian Triassic Extinction Biota NOT a Disaster Ecology?

Sudden and extreme hyperthermals, low-oxygen, and sediment influx drove community phase shifts following the end-Permian mass extinction

Authors:

Pietsch et al

Abstract:

We present a correlated record of carbon isotope geochemistry and sedimentological analysis for the Lower Triassic Werfen Formation from the Italian Dolomites. Macro- and mid-sized fossil diversity, ecology, and climate sensitivity are included to provide an integrated account of the benthic response to paleoenvironmental change. Novel communities developed in the wake of the mass extinction during pervasive fluctuations in environmental conditions. In the sedimentary sequences of the Werfen Formation of the Italian Dolomites, microbialites, microconchids, foraminifera, and ubiquitous flat-clams, formed a complex community within the first 500,000 years. Later, increased sea-surface temperatures and inundation of the seafloor with siliciclastic sediments favored infaunal bivalves and microgastropods. Persistent trends in the environment can produce directional, often irreversible, community shifts defined here as phase shifts. Phase shifts in ecosystem structure can be driven by environmental shifts across threshold boundaries to produce an “abrupt and dramatic” novel community composition, a phenomenon readily observed during the Early Triassic. Previously described “disaster forms” including flat clams, microconchids, foraminifera, and microbialites are re-envisioned as a phase shift community. We hypothesize that the unique, persistent, and reoccurring microbialite and mid-sized fauna assemblages observed during the initial recovery from the end-Permian mass extinction and re-appearing throughout the Early Triassic typify a phase shift community. In the Smithian, infaunal bivalves and microgastropods represent a second phase shift community developed in response to a persistent, directional rise in sea-surface temperatures and enhanced sediment influx. We compare and contrast phase shifts with other models for ecosystem recovery including trophic, competition, and Earth System Succession.

Lystrosaurus LIved Fast, Died Young After Permian Extinction

Two hundred and fifty-two million years ago, a series of Siberian volcanoes erupted and sent the Earth into the greatest mass extinction of all time. As a result of this mass extinction, known as the Permo-Triassic Mass Extinction, billions of tons of carbon were propelled into the atmosphere, radically altering the Earth's climate. Yet, some animals thrived in the aftermath and scientists now know why.

In a new study published in Scientific Reports, a team of international paleontologists, including postdoctoral scholar Adam Huttenlocker of the Natural History Museum of Utah at the University of Utah, demonstrate that ancient mammal relatives known as therapsids were suited to the drastic climate change by having shorter life expectancies and would have had a better chance of success by breeding at younger ages than their predecessors.

The research team studied growth patterns in therapsids from the South African Karoo Basin, a paleontologically significant area which preserves a wide range of fossils from the Permian to the Early Jurassic, or 300-180 million years ago.

By examining their bone microstructure before and after the extinction boundary, Huttenlocker and his colleagues were able to study how growth patterns in therapsids were affected by the extinction. By studying body size distributions in particularly abundant species from the Permian and Triassic, the team was able to interpret shifts in size class structure and in rates of survivorship.

"Therapsid fossils like Lystrosaurus are important because they teach us about the resilience of our own extinct relatives in the face of extinction, and provide clues to which traits confered success on lineages during this tubulent time. Lystrosaurus was particularly prolific, making it possible to build a large dataset and to sacrifice some specimens for histology to study the growth patterns recorded in its bones," said Huttenlocker, one of the paper's authors.

"Before the Permo-Triassic extinction, the famous therapsid Lystrosaurus had a life span of about 13 or 14 years based on the record of growth preserved in their bones," said Field Museum paleontologist Ken Angielczyk, another one of the paper's authors. "Yet, nearly all of the Lystrosaurus specimens we find from after the extinction are only 2¬-3 years old. This implies that they must have been breeding when they were still [relatively young] themselves."

This adjustment in life history also meant a physical change for Lystrosaurus. Before the mass extinction, this creature would have been a couple meters long and weighed hundreds of pounds—about the size of a pygmy hippo. Post-extinction, its size dropped to that of a large dog, in large part due to its altered lifespan. Yet, these adaptations seemed to pay off for Lystrosaurus. Ecological simulations show that by breeding younger, Lystrosaurus could have increased its chance of survival by 40% in the unpredictable environments that existed in the aftermath of the extinction.

link.

here, here and here, too.

Verbebrate Coprolites Became Less Diverse During the Permian/Triassic Extinction

Reduction of vertebrate coprolite diversity associated with the end-Permian extinction event in Vyazniki region, European Russia

Authors:

Niedźwiedzki et al

Abstract:

This study investigates the paleoecological significance of vertebrate coprolites collected from seven sections and three lithofacies of the uppermost Permian and lowermost Triassic succession from the Vyazniki site in the European part of Russia. The analysed specimens (coprolites and possibly some cololites) were grouped into nine morphotypes (A–I).The coprolite morphotypes were characterized geochemically and compared to the record of other Permian and Triassic coprolites worldwide. Based on the stratigraphic position, shape, structure and composition, all morphotypes were linked to supposed producers. The phosphatic composition of most of the morphotypes and inclusions of arthropod remains, fish scales and bone fragments, suggest that they were produced by carnivores, but non-phosphatic, carbonate-rich, large and oval-shaped coprolites with impressions after plant remains have also been found. The extinction of terrestrial vertebrates around the Permian–Triassic boundary in Russia is interpreted to have occurred within a few thousands of years. Here, we show a pattern of coprolite morphotypes disappearing across this boundary that is consistent with a relatively sudden change in the vertebrate faunal composition across this interval.

The End of All Things #3

Cretaceous-Paleogene (K-Pg/KT) Mass Extinction:

The Chicxulub Impact Crater will be drilled. Some are saying for the first time, but I do believe the original oil workers who reported it back in the 80s (?) did so before.

There was a partial collapse of the marine carbon pump at the K-Pg boundary.marine

Permian Triassic Mass Extinction:

There is contrary evidence from conondont tooth oxygen isotopes suggesting a sharp temperature drop right at the PT Extinction. This is contrary to the global cooking scenario.

The Permian ocean bottom waters in China were not anoxic at the time of the PT Extinction.

In South China, the redox conditions were fluctuating at the PT Boundary.

The Kayitou Formation in China appears to have the terrestrial record of the PT Extinction.

There is also evidence of cyanobacteria blooms from China as well across the PT.

Devonian Mass Extinctions:

Here's evidence of what happened during the Famenian-Frasnian Event (aka mass extinction) in Devonian in China.

There was a disruption in the nitrogen cycle at the end Devonian Mass Extinction.

Here's some more interesting evidence of what was going on during the end Devonian Mass Extinction.

End of all Things #1: a Mass Extinction Aggregation Post

Ediacaran/Cambrian Extinction:

Were the Ediacaran's wiped out, in part and the Cambrian Explosion initiated by greatly increased UV radiation?

Permian Triassic Mass Extinction:

The Permian Triassic boundary has been geochronologically located in the Spanish Pyrenees and produced an interesting and diverse fauna from the early Triassic.

The early Triassic locales of the Persian Gulf show evidence of repeated and sustained conditions like during the mass extinction itself.

Cretaceous-Paleogene (KT) Mass Extinction:

Another extraordinary claim that the KT/K-Pg mass extinction was caused by dark matter has been made.

Sixth Mass Extinction:

The carbon dates in North America appear to match well with the Human Overkill Hypothesis for the reason why the megafauna (mammoths, sloths, dire wolves, etc) went extinct.

What were the implications of the loss of large Pleistocene carnivores on the ecosystem?

Or for that matter for the impact of the loss of ALL the missing megafauna on the ecosystem?  Or more specifically on the forests?  Was the impact uniform or variable on the ecosystems of North and South America?

What were the changes on the nutrient cycle with the extinctions taking place?

Or!  Gasp!  The lack of mammoths farts on the atmosphere?

Or in the sea coast, what about the impacts of the extinction of the stellar's sea cow?

The data strongly supports the extinction of Australia's giant bird, Genyornis, as being caused by humans.

In fact, multiple sources of data suggest humanity was the cause of the extinctions in the Sahul (greater Australia).

META:

The proposed planet 9, proposed by Caltech astronomers, is unlikely to have anything to do with the mass extinctions on Earth.  Even so, if it pans out, for historical reasons, I hope they name the new planet 'Nemesis.'

Some Permo-Triassic Hypoxic Shallow Waters From Hunan, China

Depositional conditions and revised age of the Permo-Triassic microbialites at Gaohua section, Cili County (Hunan Province, South China)

Authors:

Wang et al

Abstract:

In many tropical shallow water regions the end-Permian mass extinction event occurs at the top fossiliferous packstone beds and is immediately followed by the development of microbialite facies. Both the age and redox conditions of the microbialite have been debated and both factors are addressed here in a study of the Gaohua section (Cili County, Hunan Province, China): specifically the size distribution of pyrite framboids and high-resolution conodont biostratigraphy. The framboids populations show a broad size range with examples up to 30 microns in diameter, and indicating dysoxic but not anoxic depositional conditions. More intense dysoxia is recorded in interbedded laminated micrites but not beds of giant ooids. Both the Hindeodus parvus zone and Isarcicella isarcica zones were established with the microbialite beds being confined to the H. parvus zone. Therefore, the formation of microbialite postdates the end Permian main mass extinction and records oxygen-poor conditions even in a shallow-water setting such as Gaohua section at Cili.

Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

Authors:

Komar et al

Abstract:

Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (∼252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here, we identify the deficiencies of a simplified calcium model employed in several previous studies and we demonstrate the importance of a fully coupled carbon-cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the LOSCAR model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of greater than 6oC.

Siberian Traps Released a Large Amount of Halogen Gases During Eruption, Contributed to Mass Extinction

The basalt pipes of the Tunguska Basin (Siberia, Russia): High temperature processes and volatile degassing into the end-Permian atmosphere

Authors:

Polozlov et al

Abstract:

A number of mechanisms have been proposed to explain the end-Permian crisis. Many of them explore the link between this catastrophe and the Siberian Traps. We test the hypothesis that eruption of thermogenic gas generated in contact aureoles around igneous sills intruded into evaporite sequences of the Tunguska Basin triggered the crisis. In particular, we test the idea that the aspect that breccia pipes represent conduits for voluminous gas migration from the deep basins to the atmosphere. This contribution sheds new light on the pipe formation based on new field and borehole observations and electron microscopy analyses. Of more than three hundred mapped magnetite-bearing basalt pipes, 43 are classified as diatremes. The diatremes are usually circular or elliptical, with multiple zones of brecciation reaching the surface, sometimes with preserved in-filled crater lakes. The pipe diameter on the surface varies from a few tens of meters for small single diatremes to about a kilometer. The largest crater lake area is 2.7 km2. We have conducted a detailed study of the breccias in the Sholokhovsk basalt pipe located within the Nepa potash deposit in the Tunguska Basin, Siberia, Russia (about N 59° and E 107°) and find that the breccias are cemented by carbonate matrix (calcite, dolomite) and halite. Breccia clasts are altered at various temperatures, evidenced by growth of albite and garnet from basaltic glass, and diopside, garnet, magnetite and chlorine-bearing amphibole (up to 1.8% Cl) in altered magmatic clasts. These mineral assemblages suggest high temperature interactions with evaporites within the pipe conduits. The large number of pipes support that degassing of halogen-rich volatiles was a widespread and violent process with implications for the end-Permian crisis.

Did the Siberian Traps Begin With an Ooze or a Bang?

The onset of flood volcanism in the north-western part of the Siberian Traps: Explosive volcanism versus effusive lava flows

Authors:

Jerram et al

Abstract:

The Siberian Traps large igneous province was formed during the end-Permian, about 252 Ma ago. Basaltic melt was injected into the organic and salt rich Tunguska sedimentary basin, forming interconnected sill complexes and associated hydrothermal vent complexes. Thick deposits of basaltic tuff and tephra covered the paleosurface before the onset of flood volcanism, commonly taken as direct evidence for the explosive nature of the initial phase of volcanism. The field work in this study revealed that tuffs are virtually absent along a 150 km long transect along the Dyupkun lake and Kureika river, even though tuff is shown on available geological maps. Towards the south and west, the transition between the end-Permian sediments and the flood basalts is either characterized by thin (2–5 m) to no tephra deposits (Khantaika area), hyaloclastites and associated lake-deposited tephra (Kureika area), or massive tephra deposits from local eruptive centers (Severnaya area). The new results can be put into the context of other studies about volcanic tuff horizons in Siberia, and questions the notion of province-scale explosive volcanism in Siberia during the onset of flood volcanism. Moreover, the main thicknesses of explosive tuff deposits, up to 700 m, are located in the central and southern parts of the province where the LIP erupted through thick Cambrian salt and carbonate sequences. Since numerous phreatomagmatic pipes are present in these areas, we suggest a causal relationship between deep magma–sediment interactions, explosive eruptions and the resulting environmental stress that initiated the end-Permian mass extinction.

Comparing the end Triassic and end Permian Mass Extinctions

A tale of two extinctions: converging end-Permian and end-Triassic scenarios

Authors:

VAN DE SCHOOTBRUGGE et al

Abstract:

The end-Permian (c. 252 Ma) and end-Triassic (c. 201 Ma) mass-extinction events are commonly linked to the emplacement of the large igneous provinces of the Siberia Traps and Central Atlantic Magmatic Province, respectively. Accordingly, scenarios for both extinctions are increasingly convergent and cross-fertilization of ideas has become important. Here, we present a synthesis of extinction scenarios based on a critical assessment of the available palaeontological, sedimentological, geochemical and geophysical evidence. How similar were the extinction events, what gaps exist in our understanding and how can a comparison of the events enhance our understanding of each event individually? Our focus is on the most important proximate kill mechanisms including: climate change and atmospheric pollution; increased soil erosion, weathering and runoff; forest dieback and the spread of pathogens; and ocean temperature changes, anoxia and acidification. There is substantial evidence to suggest that very similar kill mechanisms acted upon late Permian as well as Late Triassic ecosystems, strengthening the hypothesis that the ultimate causes of the mass-extinction events were similar.

Global Climate Perturbations During the Permo-Triassic Mass Extinctions

Global climate perturbations during the Permo-Triassic mass extinctions recorded by continental tetrapods from South Africa

Authors:

Rey et al

Abstract:

Several studies of the marine sedimentary record have documented the evolution of global climate during the Permo-Triassic mass extinction. By contrast, the continental records have been less exploited due to the scarcity of continuous sections from the latest Permian into the Early Triassic. The South African Karoo Basin exposes one of the most continuous geological successions of this time interval, thus offering the possibility to reconstruct climate variations in southern Laurasia from the Middle Permian to Middle Triassic interval. Both air temperature and humidity variations were estimated using stable oxygen (δ18Op) and carbon (δ13Cc) isotope compositions of vertebrate apatite. Significant fluctuations in both δ18Op and δ13Cc values mimic those of marine records and suggest that stable isotope compositions recorded in vertebrate apatite reflect global climate evolution. In terms of air temperature, oxygen isotopes show an abrupt increase of about + 8 °C toward the end of the Wuchiapingian. This occurred during a slight cooling trend from the Capitanian to the Permo-Triassic boundary (PTB). At the end of the Permian, an intense and fast warming of + 16 °C occurred and kept increasing during the Olenekian. These thermal fluctuations may be related to the Emeishan (South China) and Siberian volcanic paroxysms that took place at the end of the Capitanian and at the end of the Permian, respectively. Vertebrate apatite δ13Cc partly reflects the important fluctuations of the atmospheric δ13C values, the differences with marine curves being likely due to the evolution of local humidity. Both the oxygen and carbon isotope compositions indicate that the PTB was followed by a warm and arid phase that lasted 6 Ma before temperatures decreased, during the Late Anisian, toward that of the end-Permian. Environmental fluctuations occurring around the PTB that affected both continental and marine realms with similar magnitude likely originated from volcanism and methane release.