Dear List, I just want to express my views on this subject and then tend to more pressing issues.
It is interesting to note that similar arguments were presented when discussing SNCs. A lot of groups had a hard time believing that these series of rocks actually came from Mars. Now, you would be hard pressed to find somebody that would argue that they came from anywhere else. As far as I know, a single argument discounting Mercury as the origin for NWA 2999 was presented. This argument makes assumptions based on NWA2999 being an igneous rock. NWA 2999 was determined without a doubt to be a metamorphic rock(interlocking grains with triple junctions). Furthermore, formulas used to describe igneous processes here on Earth were used to describe a plutonic rock from a different planetary body as far as I can surmise. I guess this would be alright if the other planetary body was just like Earth with the same gravity, atmospheric pressure, water and so on. It would have been nice if the authors of this paper actually took the time to examine a piece NWA 2999. I don't think they have ever seen a piece of this meteorite. All that would have been required is to merely ask for a piece and they would have been supplied. As for it being too metal-rich, the metal was found to be introduced by the impactor. A great number of scientific heavyweights are listed as authors and coauthors representing 100s of year of combined experience so for now, they have my attention. A List debate will not suffice to sway my opinion one way or another. I think it best to keep an open mind in regards to Mercury being the PB for Angrites. Look what open minds did for the SNCs! Save the Earth, It is the only planet that serves beer. Adam --- David Weir <[EMAIL PROTECTED]> wrote: > Hello Sterling and hopeful Hermean collectors, > > The angrites have FeO contents in the general range > of ~25 wt%, so if > they are from Mercury this does not conform to your > inverse iron core > ordering, unless the core of Mercury was not fully > differentiated before > the impact-related dissemination occurred. Some > angrites like NWA 2999 > do contain too much iron to be consistent with > representing a completely > differentiated body. As for the stable orbit, the > iron cores of early > differentiated bodies which formed near Mercury and > now stored in the > inner asteroid belt is a good point, although I was > thinking about > possible Lagrange-like regions. Storage in the the > inner asteroid belt > is definitely more reasonable. > > For Rob, here is some CRE age info: > > The results of CRE age studies (Eugster et al., > 2002) utilizing > cosmogenic nuclide data indicate that the CRE age of > D'Orbigny (12.3 > +/-0.9 m.y.) is significantly different from that of > other angrites > studied: Sah 99555 (6.6 +/-0.8 m.y.), Asuka 881371 > (5.4 +/-0.7 m.y.), > Angra dos Reis (55.5 +/-1.2 m.y.), LEW 86010 (17.6 > +/-1.0 m.y.), and LEW > 87051 (~0.2 m.y.). All or most of these angrites > represent unique > ejection events on the angrite parent body. I don't > have CRE data yet > for the latest finds. > > David > > ______________________________________________ > Meteorite-list mailing list > [EMAIL PROTECTED] > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://six.pairlist.net/mailman/listinfo/meteorite-list
