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Re: Mars again

> As far as the two martian meteorites falling the same month and day
> could be be dealing in a double impact on Mars in two areas of the
> planet with simular orbits that happened to fall different years when
> things were right?? Just a thought, though I don't know how you could
> prove this other than cosmic exposure age while in orbit.

> Chassigny has a cosmic ray age of about 10 million years. Zagami has
> a cosmic ray age of about 2.5 million years. I think this rules out
> that they came from a simultaneous double impact on Mars.


Hello Al, Ron, and List,

In support of Ron's response to AL's post, I'd like to present Table 1
from Treiman's article in METEORITICS:


TREIMAN A.H. (1992) Fall days of the SNC meteorites: Evidence
for an SNC meteoroid stream, and a common site of origin.
(Meteoritics 27-1, 1992, 93-95)

TABLE 1. Relevant data on SNC meteorites.

                                                                                        
(Ga) = Igneous age
(Ma) = Exposure age

Meteorite    Fall date      Fall time*  Lithology   (Ga)    (Ma)

Chassigny  Oct. 03, 1815    08:00    chassignite  1.3    10
Nakhla      Jun. 28, 1911     09:00    nakhlite       1.3    11
Lafayette         find                -         nakhlite        1.3   11
Governador    find                -          nakhlite       1.3    09
Valadares
Zagami    Oct.  03, 1962       A.M.  shergottite 0.18-1.3  2.6
Shergotty  Aug. 25, 1865      09:00 shergottite 0.18-1.3  2.5
ALHA 77005    find              -        shergottite 0.18-1.3  2.8
EETA 79001    find              -        shergottite 0.18-1.3  0.5

* Times are local.
Data from Bogard et al. (1984), Graham et al. (1985), McSween (1985),
and R. Haag (1991; pers. comm.).


Best regards,

Bernd

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