New Study: Deccan, not Chicxulub, Killed Dinos

[Schneibster]

Merka used to be affixed to the Western side of Pangea, and had already drifted a pretty way away from it by the time the KT event happened, so, yep, even then, India was about as far as you could be from Chicxulub at those latitude levels.

So were they in fact antipodes?

Not exactly, at the end of the Cretaceous the antipode of Chicxulub would have been just off the NW coast of Australia.

I would have said a lot closer to what's now Indonesia. And closer to the Indian subcontinent than to Australia.

In any case, the Decan Traps started erupting before the Chicxulub impact so there can be no cause-and-effect. Can't remember the reference, but there are dinosaur bones, eggs etc preserved in the sediments deposited between individual flows of the Decan Traps, so the dinos were doing well living between eruptions up until the extinction.

That would be the first phase, which was much less violent and caused much less variation in the foraminifera.

[Schneibster]

Anybody care to speculate on how long the "nuclear winter" was, if it happened? If the planet was in trouble from the Deccan, the asteroid impact would make it worse. Same thing if the sequence is reversed. So a nuclear winter would be bad, but for how long.

My guess is less that three years, because that's how long the reptilians that survived would be able to hibernate.

Estimates I've read on the impact event are in decades; phase II of the Deccan Traps eruptions went on for thirty thousand plus years.

I'm good with that time period, but not with the E.L.E. being nearly that long. If the volcanism had produced lethal conditions for 30K years what life other than that around the black smokers would have survived, especially the large lizards that we know continued on afterwards?

You should probably read the linked article and the Wikipedia articles on the Deccan Traps and the Chicxulub event. The marked decrease in larger, more complex plankton is pretty dramatic.

[Berthold]

The animals that would surely get extinct by a global, long-duration "nuclear winter" are the marine* turtles. They survived, however.

*Dear Brits, I know that this is a pleonasm. However, there are US members, too.

[Horwood Beer-Master]

...I'm good with that time period, but not with the E.L.E. being nearly that long...

I've nothing against the idea that the cause of a mass extinction could play-out over a prolonged period of time, as long as the fossil record indicates a more or less continuous decline in species number and impoverishment of ecosystems until eventually the vast bulk of the former biodiversity has disappeared - all seemingly occurring in a way consistent with the suspected cause.
What I have however against Deccan as the cause of the KT however is the fact that right up to the day of the Chicxulub impact, ecosystems on every landmass on earth were healthy enough to be supporting great herds of mega-herbivores, preyed-upon by mega-carnivores. Whatever other environmental effects the Deccan eruptions may be demonstrated to have had, it's clear that at the time of Chicxulub they can't have been said to have pushed life to the edge on a planetary scale. The best you could possibly perhaps prove is that the Deccan eruptions may have hampered life's recovery after Chicxulub - but that doesn't seem to me an easy thing to prove one way or the other.

FF are you familiar with the claims about Hudson's Bay having an impact crater that killed off the megafauna, mammoths, mastodons, etc.?

Personally, I'd think the signs of such a recent massive impact would be a bit more glaringly obvious.

[Gawdzilla Sama]

FF are you familiar with the claims about Hudson's Bay having an impact crater that killed off the megafauna, mammoths, mastodons, etc.?

Yep, the idea that Hudson Bay is a huge crater has been around for a long time - I think at least since the 1960s. The very circular nature of arc is the reason for the speculation. But no one have found any actual evidence - like shock metamorphosed rocks.

I saw a boob tube special that claimed they had support for this based on micro diamonds buried in mastodon tusk. Supposedly they came screaming back to Earth after the impact and impacted the tusks so hard they were buried an inch or more into them. I don't know the terminal velocity for things the size of dust motes, but I doubted then and doubt now they could penetrate ivory.