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icbmike_for_realz t1_j4u7pzk wrote

Reply to comment by IAmTheFloydman in Extinction of the Dinosaurs: What did I miss? by cakedayCountdown

What does volcanism mean in this context?

Obviously it doesnt mean that a massive bunch of dinosaurs were too close to active volcano and melted.

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BobbyP27 t1_j4u9of0 wrote

Large explosive volcanic eruptions can pump enough particulate matter into the high atmosphere to interrupt weather patterns. One of the largest in recent history, the eruption of Mount Tambora in 1815, for example, caused the "year without summer", and a number of similar eruptions happened earlier in recorded history where we did not, at the time, know the source, but have since discovered the locations. We know from geological evidence, far far larger volcanic eruptions and events have taken place, and an event on such a scale could cause sufficient particulate matter to enter the atmosphere that it could create a period of several years of insufficient sunlight reaching the surface of the earth to massively disrupt ecosystems and create a mass extinction event. There is geological evidence that one such event, in the Deccan Traps of modern day India took place at the right sort of time (on a geological scale) and was large enough that it is a plausible candidate for causing the extinction event that ended the dinosaurs.

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CrustalTrudger t1_j4urjw2 wrote

> an event on such a scale could cause sufficient particulate matter to enter the atmosphere that it could create a period of several years of insufficient sunlight reaching the surface of the earth to massively disrupt ecosystems and create a mass extinction event.

So the potential cooling effects of large explosive volcanic eruptions (e.g., events like the 1815 Mount Tambora eruption) are not disputed, but this is not actually relevant for Deccan Traps volcanism or the suggested kill mechanisms related to them. For the Deccan Traps as the cause of the K-Pg extinction, the kill mechanism may have been global warming from pulses of greenhouse gases released by the volcanism (e.g., Tobin et al., 2012) or a combination of this along with ocean acidification and ocean warming (e.g., Keller et al., 2020). I.e., flood basalt eruption and its effects do not equal large caldera eruption and its effects.

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peoplerproblems t1_j4wlqp9 wrote

So you got me curious about multiple factors relating to the current and previous extinction events.

O-S was climate and atmospheric composition, greenhouse effect of volcanos, and loss of oxygen.

The Devonian event(s) were ecological, but I can't find much on it.

P-T was ocean acidification, oxygen loss, greenhouse caused by volcanism

T-J was again, acidification, climate changed, and oxygen loss.

K-G, again, acidification, climate change, but I can't find atmospheric composition.

Regardless, it appears that the extinctions occur once those worldwide changes start, regardless of the cause. What I'm curious about now is if there is any evidence at how inhospitable the planet was by the end of the extinction events.

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tandjmohr t1_j4wuw43 wrote

In this specific case they are referring to Flood Volcanism. The Deccan Traps (I probably spelled that wrong) are a large igneous province in India where, about the same time as the Dino asteroid (geologically speaking), large cracks opened in the crust and absolutely immense volumes of basaltic lava poured out in flows hundreds of feet thick covering thousands of square miles one on top of the other. The cumulative depth of these flows are measured in miles.

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icbmike_for_realz t1_j4wzltr wrote

Over what time span did these flows spread?
Would an individual dinosaur be overtaken or could they run away?

Or were they pressured by being pushed out of their environments?

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tandjmohr t1_j4x81hw wrote

Some of the individual flows happened within 50,000 years of each other. I believe the total time of the flows was 750,000 to a million years or so.

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