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Re: More on the Antarctic impacts
>The last paragraph is weird, though. For all that's known, magnetic field
>reversals happen totally at random, and how an impact could cause one --
>considering or not that Chicxulub does not correlate with one! -- is beyond
The whole story is weird. Impacts of that size would leave a global
signature but nothing in particular happened 780 000 BP (except the field
reversal). There is any number of marine and terrestrial profiles covering
that interval and there is no shocked quartz, no spherules, no nothing.
Impactors of that size would easily go through the ice and eject large
quantities of bedrock globally (with an antipodal concentration, i. e. near
the North Pole). Most of Antarctica is Precambrian shield so there should
be plenty of quartz to shock.
Note that the much smaller Eltanin oceanic impact which occurred in the
southern ocean c. 2 million years ago left a strong regional signature.
I suggest that either
a) The "impact craters" are something else
b) They are a lot older than 780 KY (there are for example some Late Eocene
impact layers that have never been linked to a crater).