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 [EMAIL PROTECTED] (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...." ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
