Graham Macleod
4/2/2016 9:40:52 PM |
Beautiful sculpted S.A. Herbert,
The regg's and the holes are evident of a really hot meteorite piece streaking through the atmosphere!
Well done M8! |
MexicoDoug
4/2/2016 5:46:45 PM |
I don't think we should jump to conclusions since most of us are biased in favor of impacts. This should be easy enough to study. Why not both phenomena happening? In the particular MPOD case here, I'd suggest there is just enough raised material to explain where the extra material goes when a bubble pops. Metal is very cohesive and possibly still ablating. These pits are frequently just too perfect looking to me. Thumbprints themselves prove that material can be removed unevenly. I'd even say you don't need any exploding bubbles at all, just ablation doing the job. Look up Yellowstone mud pots and watch the formation and popping and what remains afterward before settling ... |
Herbert
4/2/2016 1:09:30 PM |
Indeed, Krinov described these features as pits "formed by bubbles of gas which seperate from the meteorite at the moment pf crustal foration" (see "Principles of Meteoritics, p. 276-277). Later, Killgore and McHone interpreted them "as impact craters resulting from high velocity collisions between meteoritic particles during the latest stages of atmospheric flight" ("Small Impact Craters on Sikhote-Alin Iron Meteorite Surfaces", LPSC 98, Abstract 1839 - you can find this online if you search for the title).
I do, however, wonder if there are enough volatiles in a solid iron meteorite to create pits of this size, and if the evaportion of such volatiles has enough power to create the raised rims of bent-over metal seen around the large "crater" in the above sample.
But maybe both types exist?
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Larry Atkins
4/2/2016 9:29:40 AM |
Are they impact pits or volatile material heating up and exploding outward? These pits are evident on the irons from Franconia as well, which I've been told are not impact pits. They look the same to me, I doubt there are two different explanations. |
Dr. Mike Reynolds
4/2/2016 5:41:15 AM |
"The Impact Crater" -- I love it!
As Graham already noted, the impact pit on this S-A is really a nice characteristic of the sample. Thanks for sharing it with us, Herbert. |
Graham
4/2/2016 4:51:13 AM |
Love the ones with impact pits...very nice.
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