Central Atlantic Magmatic Province was GeoChronologically Aligned WIth Triassic Jurassic Mass Extinction

Geochemical consequences of intense pulse-like degassing during the onset of the Central Atlantic Magmatic Province

Authors:

Paris et al

Abstract:

The Triassic–Jurassic boundary (TJB) is marked by one of the five largest mass extinctions of the Phanerozoic and the eruption of a large igneous province: the Central Atlantic Magmatic Province (CAMP). The TJB is characterized by a carbonate production crisis, by negative excursions in the carbon isotopic ratio of buried organic matter, and by successive peaks in atmospheric CO2. Here we use the numerical model GEOCLIM to explore the possible connections between the CAMP emplacement and the observed carbon cycle perturbations. Different degassing scenarios linked to the CAMP eruption are explored. We show that the emission of realistic amounts of CO2 that follow a geologically constrained degassing scenario as short-term peaks (less than 10 ka) leads to successive decrease in carbonate production, as observed in the geological record. We also calculate the evolution of carbon isotopes and show that our model reproduces the amplitude of the isotopic excursion with a volcanic degassing of CO2 characterized by a carbon isotopic composition of − 20‰. Such low values could be associated to carbon pools of light isotopic composition located at the transition zone [Cartigny, P. 2010, Earth and Planetary Science Letters, v. 296, p. 329–339] and not necessarily to biogenic methane release. Finally, the model predicts a succession of short-term CO2 rises, with an amplitude in close agreement with available proxy-based reconstructions.

YAGUMETs! Flood Basalt Eruptions Mass Extinction Impacts are Depend on WHERE the Eruption Takes Place

The effects of large igneous provinces on the global carbon and sulphur cycles

Authors:

Jones et al

Abstract:

The correlation between large igneous provinces (LIPs), extinction events, and rapid climate change suggests that volcanism can have a detrimental impact on Earth surface conditions. Changes in atmospheric and ocean chemistry, particularly the climate-sensitive carbon and sulphur cycles, are among the most probable processes for inducing global environmental stress. However, the interactions and feedbacks between volcanism and these cycles are numerous and complex, making the characterisation of the response to a LIP challenging. Here we summarise the sources and sinks of carbon and sulphur from large scale volcanism and magmatism using information from modern and ancient systems. For the sources, we review the current understanding of volcanic emissions, and explore the relative contributions and importance of magma-derived degassing versus volatile release from sediments affected by igneous intrusions and lava. In addition, we explore the various ways in which LIPs can reduce atmospheric concentrations of these same elements. The relative influences of each source and sink are in part determined by the mode of LIP emplacement and eruption style, along with the subsequent timescales of such effects. We focus on a few key examples, including the Siberian Traps, the Paraná-Etendeka, and the Central Atlantic Magmatic Province (CAMP), to demonstrate how the environmental impact can vary considerably with differing modes of emplacement, LIP duration, and eruption styles. In particular, we show that the host rocks can have a dominant role as a source or sink of emissions, depending on the lithologies affected by the LIP emplacement.

Sulfur Very Important for Volcanicly Driven Mass Extinctions?

Microanalyses link sulfur from large igneous provinces and Mesozoic mass extinctions

Authors:

Callegro et al

Abstract:

Volcanic gases can have devastating impacts on Earth's environment and life. However, measurement of volatile elements in prehistoric magmas is challenging. We present a new method for determining sulfur contents in magmas using its concentrations in clinopyroxenes and an experimentally determined crystal-melt partition coefficient. Using this method we compared magmatic sulfur contents in the Paraná-Etendeka large igneous province (LIP; South America) and two other similarly sized LIPs, the Central Atlantic magmatic province (CAMP) and the Deccan Traps (India). We found that the CAMP and Deccan Traps, both associated with major extinction events, contained high magmatic sulfur concentrations, up to 1900 ppm. Conversely, the Paraná-Etendeka LIP, lacking significant environmental effects, had substantially lower magmatic sulfur concentrations, less than 800 ppm.

They ought to look at the Permian Extinction/Siberian Traps.  I am a bit surprised they did not.  And, again, the Deccan Traps have dinosaur fossils below, between and above the lava flows.

Triassic-Jurassic Extinction Probably Caused by Global Warming Rather Than Ocean Acidification

Radiolarian biodiversity dynamics through the Triassic and Jurassic: implications for proximate causes of the end-Triassic mass extinction

Authors:

Kocsis et al

Abstract:

Within a ∼60-Myr interval in the Late Triassic to Early Jurassic, a major mass extinction took place at the end of Triassic, and several biotic and environmental events of lesser magnitude have been recognized. Climate warming, ocean acidification, and a biocalcification crisis figure prominently in scenarios for the end-Triassic event and have been also suggested for the early Toarcian. Radiolarians, as the most abundant silica-secreting marine microfossils of the time, provide a control group against marine calcareous taxa in testing selectivity and responses to changing environmental parameters. We analyzed the origination and extinction rates of radiolarians, using data from the Paleobiology Database and employing sampling standardization, the recently developed gap-filler equations and an improved stratigraphic resolution at the substage level. The major end-Triassic event is well-supported by a late Rhaetian peak in extinction rates. Because calcifying and siliceous organisms appear similarly affected, we consider global warming a more likely proximate trigger of the extinctions than ocean acidification. The previously reported smaller events of radiolarian turnover fail to register above background levels in our analyses. The apparent early Norian extinction peak is not significant compared to the long-term trajectory, and is probably a sampling artifact. The Toarcian Oceanic Anoxic Event, previously also thought to have caused a significant radiolarian turnover, did not significantly affect the group. Radiolarian diversity history appears unique and complexly forced, as its trajectory parallels major calcareous fossil groups at some events and deviates at others.

More Evidence Tying CAMP Eruptions to Triassic-Jurassic Mass Extinction

Scientists examining evidence across the world from New Jersey to North Africa say they have linked the abrupt disappearance of half of earth's species 200 million years ago to a precisely dated set of gigantic volcanic eruptions. The eruptions may have caused climate changes so sudden that many creatures were unable to adapt—possibly on a pace similar to that of human-influenced climate warming today. The extinction opened the way for dinosaurs to evolve and dominate the planet for the next 135 million years, before they, too, were wiped out in a later planetary cataclysm

In recent years, many scientists have suggested that the so-called End-Triassic Extinction and at least four other known past die-offs were caused at least in part by mega-volcanism and resulting climate change. However, they were unable to tie deposits left by eruptions to biological crashes closely in time. This study provides the tightest link yet, with a newly precise date for the ETE--201,564,000 years ago, exactly the same time as a massive outpouring of lava. "This may not quench all the questions about the exact mechanism of the extinction itself. However, the coincidence in time with the volcanism is pretty much ironclad," said coauthor Paul Olsen, a geologist at Columbia University's Lamont-Doherty Earth Observatory who has been investigating the boundary since the 1970s.

The new study unites several pre-existing lines of evidence by aligning them with new techniques for dating rocks. Lead author Terrence Blackburn (then at Massachusetts Institute of Technology; now at the Carnegie Institution) used the decay of uranium isotopes to pull exact dates from basalt, a rock left by eruptions. The basalts analyzed in the study all came from the Central Atlantic Magmatic Province (CAMP), a series of huge eruptions known to have started around 200 million years ago, when nearly all land was massed into one huge continent. The eruptions spewed some 2.5 million cubic miles of lava in four sudden spurts over a 600,000-year span, and initiated a rift that evolved into the Atlantic Ocean; remnants of CAMP lavas are found now in North and South America, and North Africa. The scientists analyzed samples from what are now Nova Scotia, Morocco and the New York City suburbs. (Olsen hammered one from a road cut in the Hudson River Palisades, about 1,900 feet from the New Jersey side of the George Washington Bridge.)

Previous studies have suggested a link between the CAMP eruptions and the extinction, but other researchers' dating of the basalts had a margin of error of 1 to 3 million years. The new margin of error is only a few thousand years—in geology, an eye blink. Blackburn and his colleagues showed that the eruption in Morocco was the earliest, with ones in Nova Scotia and New Jersey coming about 3,000 and 13,000 years later, respectively. Sediments below that time contain pollen, spores and other fossils characteristic of the Triassic era; in those above, the fossils disappear. Among the creatures that vanished were eel-like fish called conodonts, early crocodilians, tree lizards and many broad-leaved plants. The dating is further strengthened by a layer of sediment just preceding the extinction containing mineral grains providing evidence of one of earth's many periodic reversals of magnetic polarity. This particular reversal, labeled E23r, is consistently located just below the boundary, making it a convenient marker, said coauthor Dennis Kent, a paleomagnetism expert who is also at Lamont-Doherty. With the same layers found everywhere the researchers have looked so far, the eruptions "had to be a hell of an event," said Kent.

The third piece of chronological evidence is the sedimentary layers themselves. Sedimentary rocks cannot be dated directly—one reason why the timing of the extinction has been hard to nail. Olsen and some others have long contended that the earth's precession—a cyclic change in the orientation of the axis toward the sun and resulting temperature changes—consistently created layers reflecting the alternate filling and drying of large lake basins on a fairly steady 20,000-year schedule. This idea is well accepted for more recent time, but many scientists have had doubts about whether it could be applied much farther back. By correlating the precisely dated basalts with surrounding sedimentary layers, the new study shows that precession operated pretty much the same way then, allowing dates with a give or take of 20,000 years to be assigned to most sediments holding fossils, said Olsen.

Olsen has painstakingly cataloged the layers around the time of the End Triassic, and the initial phase of the extinction occurs in just one layer—meaning the event took 20,000 years at most. But, he said, "it could have taken much less. This is the level of resolution we have now, but it's the 'less' part that is the more important, and that's what we are working on now."

Many scientists assume that giant eruptions would have sent sulfurous particles into the air that darkened the skies, creating a multi-year winter that would have frozen out many creatures. A previous study by Kent and Rutgers University geochemist Morgan Schaller has also shown that each pulse of volcanism doubled the air's concentration of carbon dioxide—a major component of volcanic gases. Following the cold pulses, the warming effects of this greenhouse gas would have lasted for millennia, wiping out creatures that could not take too much heat. (It was already quite hot to begin with at that time; even pre-eruption CO2 levels were higher than those of today.) Fossils show that heat-sensitive plants especially suffered; there is also evidence that the increased CO2 caused chemical reactions that made the oceans more acidic, causing populations of shell-building creatures to collapse. As if this were not enough, there is also some evidence that a large meteorite hit the earth at the time of the extinction--but that factor seems far less certain. A much stronger case has been made for the extinction of the dinosaurs by a meteorite some 65 million years ago—an event that opened the way for the evolution and dominance of mammals, including human beings. Volcanism may have been involved in that extinction as well, with the meteorite delivering the final blow.)

Right now, it would appear that we have two mass extinctions that were tied to massive eruptions (Permian and Triassic mass extinctions). We have one that is almost certainly tied to a meteor impact (KT or K-Pg). The others are still VERY ambiguous. The Devonian was a string of extinctions. The Ordovician...is poorly understood.  Let's be careful about making proclamations about their causes until we can dig through them sufficiently.

CAMP Tied to TJ Extinction Within 30K Years Radiometrically

To incriminate a global catastrophe in the extinction of a wide swath of the biosphere, you need precise dates for two events: the catastrophe—say, an asteroid impact or volcanic eruption—and the mass extinction. At the meeting, geochronologists who measure the passage of time in the steady ticking of radioactive decay presented convincing evidence that massive eruptions at the opening of the Atlantic Ocean 201 million years ago drove the mass extinction that cleared the way for the rise of the dinosaurs.

The dating—by Terrence Blackburn of the Carnegie Institution for Science in Washington, D.C., and colleagues—was impressively precise. For minerals from the end of the Triassic period, 201 million years ago, the researchers reported ages to three decimal places with a 1-sigma error of about 30,000 years, just 0.015% of the ages. That kind of precision takes careful measurements of the amounts of the radioactive element of interest and the product of its decay. That's quite a feat in mineral grains that have been ravaged for hundreds of millions of years by both the environment and their own radioactivity.

[...]

Near the end of the Triassic period, millions of cubic kilometers of magma spewed from the crack that split the supercontinent Pangaea in two and started the opening of the Atlantic Ocean. Debris from the eruptions might have chilled the climate or poisoned the environment, triggering the extinction. But previous dating had had the extinction coming before the first volcanic outburst, not at the same time.

So Blackburn and his colleagues used the latest uranium-lead techniques to date volcanic samples from seven sites on the East coast of North America and one site in Morocco. They dated the end-Triassic extinction to 201.562±0.016 million years ago (subject to change in peer review). Adding in dating of sediments surrounding eruption deposits by using astronomical cycles, they could correlate the Moroccan record to the North American record, placing the extinction at the first of three eruption pulses within the small dating errors. And those errors have gotten so small that no one is disputing that the Atlantic opening megaeruptions somehow did in enough critters to unleash the dinosaurs.