Meteor Seen as Causing Extinctions on Earth

An anonymous reader writes "From the NY Times (I think you may have to register): About three dozen minuscule shards of rock unearthed in Antarctica may be the fragments of a meteor that killed most life on Earth 250 million years ago, scientists are reporting today. These rocks have yielded soccer-ball-shaped molecules known as buckyballs containing extraterrestrial gases, as well as grains of quartz with fractures that indicate a tremendous shock. The extinction 250 million years ago, in a period known as the Permian-Triassic boundary, was the largest of all. About 90 percent of species disappeared."

Comments

Pre-emptive correction

[the morgawr]

No this was not the extinction that killed the dinosaurs. This occured earlier in time.

Re:Pre-emptive correction

[the morgawr]

Paraphrased from palaeos (a little further down on that google query):

Time scale works like this (from larger to smaller): Eon -> Era -> Period -> Epoch -> Age

The Permian was the last period of the Paleozoic Era(which ending with the mass extinction). This was followed by the Mesozoic Era (whose first period was the Triassic). While Dinosaurs first appeared in the Triassic they become dominant during the Jurassic. Dinosaurs first appeared in the Carnian age (227 to 221 million years ago, durring the late Triassic) but were "small and insignificant: bipedal bird-like carnivores, insectivores, and herbivores. "

Re:Pre-emptive correction

[kalidasa]

The dino extinction is called the K-T extinction, for Cretaceous/Tertiary (it makes sense in German, I imagine), and the one in question would be the P-T extinction, for Permian/Triassic. So this is the previous huge mass extinction event to the K-T extinction. The Dinosauria branch off from the Reptilia in early Triassic, and all Dinosauria except the Aves die off at the K-T event.

The P-T was bigger than the K-T.

Naturally-occurring Buckyballs?

[GTRacer]

I mean, I remember reading about fullerenes in Discover like 10 years ago, but I never knew they could occur naturally, or in the case of a cataclysmic impact, spontaneously.

I thought it took precise conditions to get them to form. And for these to have captured gases inside...

Weird...

GTRacer
- Go-o-o-o-al!

Re:Naturally-occurring Buckyballs?

[einstein]

my understanding is, once we learned how to make them, we learned how to look for them, and they show up all over the place. lots of ash from wood fires have buckyballs in them, for instance.

Another article

[DjReagan]

The BBC had an article on this also.

Impact-caused volcanic activity

[Vaevictis666]

If the evidence for an impact does become more compelling, that would raise another geological mystery, whether meteor impacts can set off huge volcanic eruptions. Huge eruptions in India coincided with the Yucatan meteor impact 65 million years ago, and Dr. Basu sees a clear link between the Antarctic shards and the Siberian eruptions.

Something to note is that both cases here involves a meteor impact on the opposite side of the earth from the eruptions. Coincidence?

Re:Impact-caused volcanic activity

[Yazeran]

Something to note is that both cases here involves a meteor impact on the opposite side of the earth from the eruptions. Coincidence?


Coincidence? Nope. When a spherical body like the earth or any other of the terrestrial planets is hit by a suficiently large meteor the shockwave is focused by the spherical shape and arrive at the exact opposite side of the planet resulting in a massive earthquake (actually 3, one from each of the three types of vibrations (sound) that travel through the earth with different speeds). The large one would be the surface vibrations as they would be completely focused whereas the P and S vibations which trave through the planet would be less vell focused. The P and S vibrations however vould interfere with the mantle and lower crust on the far side which is the origin of most magmas.

One spectacular evidence of this is found on Mercury where a large crater (The caloris basin) has an area on the directly opposite side which was named 'wierd terrain' by the people analysing the Mariner 10 images of Mercury.

Yours Yazeran

Plan: To go to Mars one day with a hammer.

Re:Impact-caused volcanic activity

[fluffy666]

Your hypothesis has a few problems..

a) The Earth is not perfectly spherical, and it is distinctly non-Isotropic.

b) You need to include some calculations on how much energy would actually be available from the known crater. Even under generous assumptions, we are looking at a magnitude 10.5 earthquake at best.

c) Surface waves are strongly attenuated in the crust, which is strongly anisotropic. The energy arriving at the other side of the planet would be negligable. P and S waves would not be focussed at all.

Mercury is interesting.. but you will note that this feature is 1300km across, and the impactor would have been around 150km across - 15x the diameter and therefore over 3000 times as massive; and Mercury is smaller and more isotropic than earth.

I know slashdot is slow on news but....

[waterlogged]

I know slashdot is slow on getting news but...

250 million years? ;)

Minor Planets Currently Known

[ear2ground]

This animation shows the known minor planets in the Inner Solar System presently.

This page updates regularly on newly discovered objects.
There are many more to be found. Though the risk of an impact like the one believed to have been involved is very slight.