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.

Dr Gerta Keller Trumpets a Charge: Multiple Papers About Deccan Traps and the the K-Pg/KT Mass Extinction

Dr Keller has been leading an insurgency against the idea the Chicxulub impact was the underlying event that brought about the Cretaceous-Paleogene (K-Pg) Mass Extinction (formerly the KT Extinction).  This is rather contrarian to the generally accepted theory.  

The journal Paleaeogeography, Palaeoclimateology, Palaeoecology has an issue dedicated to how volcanic eruptions impacted (see what I did there?) past mass extinctions (or didn't as it may be).  That's the reason for all the volcano related posts this past week.  

Dr Keller's 'team' has a large number of articles in the publication.  Rather than do my traditional one-paper-per-post method, I am going to do a list here of each.  The reason being I don't buy her hypothesis that the Deccan Traps caused the mass extinction during the Maastrichtian.  I've posted as much since the evidence comparing mass extinctions already strongly tied to volcanic eruptions is rather different from what is present for the K-Pg Extinction.  I wrote as much in the Stop Dreaming post.  

That said, I am sure the Deccan Traps did cause some environmental impacts (see!), but they are insufficient to have caused the mass extinction.

While I admire tenacity, I think she has crossed over to religion.  However, rather than ignoring the recent papers, since they are peer reviewed papers in a respected journal, I am going to link to each here with a very short title and a description of each and a short comment.

Upheavals during the Late Maastrichtian: Volcanism, climate and faunal events preceding the end-Cretaceous mass extinction. Keller et al present their case the Maastrichtian Cretaceous was a time a climate upheaval and ecological degradation caused by the Deccan Traps with the ecology dominated by opportunistic, disaster taxa.  My comment: T rex.  Too big.

A multi-proxy approach to decode the end-Cretaceous mass extinction. Punekar argues there are multiple bits of evidence suggest the Deccan Traps caused the mass extinction at the K-Pg, especially the release of 12 to 28 teratons of carbon. Comment: Unfortunately, in the same journal edition, the OAE1 from the Early Aptian Cretaceous is stated to have been caused by the release of 20 teratons of carbon. The OAE1 was a mass extinction but a very, very mild one. Additionally, in a surprise result, calciferous plankton actually grow MORE with higher carbon dioxide levels, not less as was expected.

Tracing acidification induced by Deccan Phase 2 volcanism. Font et al ID some potential evidence of aquatic acidification at the end of the Deccan 2 Eruptions. These are located in India. Comment: Best to check to see how global this was before making a claim of global occurrence.

Palaeoenvironmental changes associated with Deccan volcanism, examples from terrestrial deposits from Central India. Fantasia et al present evidence of local impacts of the Deccan Traps caused stressed environment from India. Their claim is the DT caused environmental stress and could have made the Maastrichtian fauna vulnerable to a mass extinction at the end of the Cretaceous. Comment: Possible, but this could be completely local. Mount ST Helens did enormous damage locally, but only modestly globally.

Climatic fluctuations and sea-surface water circulation patterns at the end of the Cretaceous era: Calcareous nannofossil evidence. Thibault et al make the argument surface plankton became stressed and lost species during the proposed Deccan Warmings. However, 100k to 140k years before the K-Pg Boundary, the plankton had regained their species richness. Comment: Interesting. Given the problems of IDing what forminifers are what species I'd be cautious. The recovery would suggest whatever stress caused by the DTs had ended though.

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.

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.

Australian Kalkarindji Continental Flood Basalt Probably did NOT Cause Cambrian Mass Extinction

The Giant Lavas of Kalkarindji: rubbly pāhoehoe lava in an ancient continental flood basalt province

Authors:

Marshall et al

Abstract:

The Kalkarindji continental flood basalt province of northern Australia erupted in the mid Cambrian (c. 511-505 Ma). It now consists of scattered basaltic lava fields, the most extensive being the Antrim Plateau Volcanics (APV) – a semi-continuous outcrop (c. 50,000 km2) reaching a maximum thickness of 1.1 km. Cropping out predominately in the SW of the APV, close to the top of the basalt succession, lies the Blackfella Rockhole Member (BRM). Originally described as ‘basaltic agglomerate’ the BRM has, in recent years, been assumed to be explosive tephra of phreatomagmatic origin, thus providing a potent vehicle for volatile release to the upper atmosphere. Our detailed field investigations reveal that this basaltic agglomerate is, in reality, giant rubble collections (15–20 m thick) forming the upper crusts of rubbly pāhoehoe lava units 25–40 m thick; covering 18,000–72,000 km2 and an estimated volume of 1,500–19,200 km3. These flows, rheologically but not chemically, distinct from the majority of Kalkarindji lavas, indicate a fundamental change in eruption dynamics. A low volatile content, induced high amounts of pre-eruptive degassing causing super-cooling and an increase in crystal nucleation and viscosity. A more viscous lava and a consistently faster rate of effusion (analogous to that of Laki, Iceland) created the flow dynamics necessary to disturb the lava crust to the extent seen in the BRM. Volatile release is estimated at 1.65 × 104–2.11 × 105 Tg total CO2 at a rate of 867 Tg a- 1 and 9.07 × 103–1.16 × 105 Tg SO2 at 476.50 Tg a- 1. These masses accounted for 0.5% of Cambrian atmospheric conditions whilst limiting factors reduced the effect of volatile delivery to the atmosphere, thus any potential global impact caused by these flows alone was minimal.

Flood Basalts Don't Cause Mass Extinctions Through Sulphuric Acid

Selective environmental stress from sulphur emitted by continental flood basalt eruptions

Authors:

Schmidt et al

Abstract:

Several biotic crises during the past 300 million years have been linked to episodes of continental flood basalt volcanism, and in particular to the release of massive quantities of magmatic sulphur gas species. Flood basalt provinces were typically formed by numerous individual eruptions, each lasting years to decades. However, the environmental impact of these eruptions may have been limited by the occurrence of quiescent periods that lasted hundreds to thousands of years. Here we use a global aerosol model to quantify the sulphur-induced environmental effects of individual, decade-long flood basalt eruptions representative of the Columbia River Basalt Group, 16.5–14.5 million years ago, and the Deccan Traps, 65 million years ago. For a decade-long eruption of Deccan scale, we calculate a decadal-mean reduction in global surface temperature of 4.5 K, which would recover within 50 years after an eruption ceased unless climate feedbacks were very different in deep-time climates. Acid mists and fogs could have caused immediate damage to vegetation in some regions, but acid-sensitive land and marine ecosystems were well-buffered against volcanic sulphur deposition effects even during century-long eruptions. We conclude that magmatic sulphur from flood basalt eruptions would have caused a biotic crisis only if eruption frequencies and lava discharge rates had been high and sustained for several centuries at a time.

Evidence From Washington Direct Impacts of Volcanic Eruptions Insufficient to Cause Mass Extinctions

Extrinsic forcing of plant ecosystems in a large igneous province: The Columbia River flood basalt province, Washington State, USA

Authors:

Ebinghaus et al

Abstract:

Volcanism associated with large igneous provinces (LIPs) has been implicated in both global climate and environmental change. To determine the impact of LIP volcanism on plant ecology we have examined plant community succession in sedimentary interbeds of the Columbia River flood basalt province (CRBP; northwest United States). Interbasaltic vegetation is characterized by primary succession communities that inhabit fresh lava surfaces until terminated by the next eruptive event, and it is assumed that longer volcanic hiatuses should lead to more mature plant communities. This expected succession trajectory is contradicted by palynological data that show that seral succession declines during the phase of waning CRPB volcanism and prolonged interbed intervals. Frequent volcanic activity and increased deposition of Snake River Plain hotspot ashes during this phase resulted in ecological disturbance of intralava field vegetation. Together with geochemical proxies from interbed sediments, this suggests that CRBP flora was largely driven by extrinsic forcing, and implies that LIP volcanism of similar scale and magnitude to that of the CRBP had a limited environmental impact. This study supports the theory that past biotic extinctions were triggered by numerous factors rather than a single geological event.