Hello Jeff, Jason, and List, I'd like to direct your attention to a very comprehensive article in MAPS where the authors extensively elaborate on this problem.
Best wishes, Bernd ----------------------------------------------------------------------------------- BENEDIX G.K. et al. (2000) A petrologic study of the IAB iron meteo- rites: Constraints on the formation of the IAB-Winonaite parent body (MAPS 35-6, 2000, pp. 1127-1141, excerpts from the abstract): 1) similarities in mineralogy and mineral and O-isotopic compositions suggest that: IAB iron and winonaite meteorites are from the same parent body 2) the precursor parent body was chondritic, although unlike any known chondrite group 3) metamorphism, partial melting, and incomplete separation of melt from residue produced: - metallic, sulfide-rich partial melts - silicate partial melts - metamorphosed chondritic materials and residues 4) catastrophic impact breakup and reassembly of the debris near peak temperature 5) mixing of materials from various depths into the re-accreted parent body Result: Molten metal from depth was mixed with near-surface silicate rock, resulting in the formation of silicate-rich IAB iron and winonaite meteorites. But: Not all of the metal melt bodies were mixed with silicate materials during this impact and reaccretion event. Consequence: There are also silicate-free IAB iron meteorites. Time frame: Ages of silicate inclusions and winonaites of 4.40-4.54 Ga indicate this entire process occurred early in solar system history. ______________________________________________ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
