[meteorite-list] puzzling Putorana

From: Dave Harris <entropydave_at_meteoritecentral.com>
Date: Thu Apr 22 09:54:09 2004
Message-ID: <004e01c1bc4a$da583460$849f0050_at_default>

Hi there,
I have just read Mr. Norton's article in this quarter's Meteorite magazine
on Putorana where he speculated that the iron in the basalt was derived from
mantle plumes conducting iron from the core to the magma chambers in the
lithosphere - I was just wondering how actually plausible that mechanism
actually was.
I thought that a more likely scenario for the creation of Putorana iron may
have been the effect of a magmatic plume coming into contact with a highly
carbonaceous sedimentary deposit and the iron compounds are then reduced to
native iron (much in the same way that commercial iron is produced by
reacting with coke). I accept that the sedimentary deposits would have to
be subducted to quite some depths before the appropriate temperature and
pressures arose, but it still seems more likely a scenario to me than a
outer liquid core streamer of iron travelling a couple of thousand
kilometres upwards, against gravity and still keeping the iron in a liquid
enough state to mix with magma.

Any ideas? I wonder if there is any overriding chemical evidence that the
iron is sourced from the core rather than liberated as part of a reduction
of mantle silicates and oxides (possibly the presence of Ni in the iron is
the evidence that supports the core theory - I dunno!)

Don't laugh at me if I have written a load of rubbish here! I need to learn
and only by thinking about this stuff and making gaffs will I learn
anything - some of you people out there know more about Geology than I will
EVER learn, so I bow to your undeniably profound knowledge!!!

Ideas/opinions please!

--
In gentle decay,
dave
IMCA #0092
imca_0092_at_hotmail.com (for IMCA member contact)
http://www.meteorites.ic24.net/index.html
http://www.meteoritecollectors.org
"I have a proof that x^n+y^n=z^n never has integer solutions for n>2.
However, it won't fit into my signature file...."

Received on Sat 23 Feb 2002 04:17:01 AM PST