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Re: Chicxulub's Antipode (Re: cause of death at KT)
Phillip Bigelow wrote:
> On Fri, 01 Sep 2006 22:09:18 +0200 David Marjanovic
> - Tsunamic effects would have been minor, because North and South America
> would have blocked the waveform from the paleo Pacific
Why? If I remember correctly, the isthmus of Panama didn't exist at that
time, if so, there was a direct connection to the Pacific.
> - What about reentering ejecta? It was probably no worse than elsewhere
> on the globe. Keep in mind that just because some material went
> suborbital or fully orbital doesn't *require* that the material must fall
> at the antipode. It could fall just about anywhere on Earth,
It can, but a substantial fraction will fall near the antipode (or rather the
antipode displaced by about 45 minutes). I'd expect quite a concentration of
ejecta near the displaced antipode.
> which is
> dictated by the ejecta's altitude (ejecta in low Earth orbit will reenter
> sooner; higher orbits may take hundreds of years to degrade to reentry).
I believe it would be mostly sub-orbital stuff that would nail the antipode.
> Let's assume for the sake of argument that the Chicxulub antipode was
> occupied by sea floor rather than by dry land. Is this part of the sea
> floor still preserved? If it is, and if the site can be located, would
> it would be worthwhile to drill into into it and see what types of
> faulting patterns characterize a mega-converging seismic event at an
That's a darned good suggestion.
> I'm thinking of the structural geology seen at the antipode of the
> Caloris [impact] Basin on Mercury and the structural geology seen at the
> antipode of the Stickney Crater on Phobos. Not to mention the antipodal
> structures on Mimas.
And a couple of the larger craters on the Moon.