Computer Science
Scientific paper
Jul 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994metic..29r.511n&link_type=abstract
Meteoritics (ISSN 0026-1114), vol. 29, no. 4, p. 511
Computer Science
8
Chemical Composition, Meteoritic Composition, Radioactive Isotopes, Shergottites, Ablation, Atmospheric Entry, Chemical Analysis, Radioactive Age Determination
Scientific paper
From cosmogenic nuclide studies of SNC meteorites exposure histories, ejection conditions from the hypothesized martian parent body, and genetic relationships between SNC meteorites were determined. Previous studies show ablation to have been very low in at least three shergottites, ALHA 77005, Shergotty, and EETA 79001. This suggests that the atmospheric entry velocity and/or entry angle of shergottites must have been much lower than of ordinary chondrites. We report the results of cosmogenic radionuclides in the newly classified SNC meteorite ALH 84001 and additional studies of ALHA 77005. Be-10 (half-life = 1.5 m.y.) and Cl-36 (0.30 m.y.) results are presented for these two meteorites along with previous measurements of the shergottite LEW 88516. Aluminum-26 (0.71 m.y.) measurements are in progress. We received two chips on opposite sides of ALH 84001. Two subsamples, at depths of 0.5-3.5 mm and 7-9 mm, from fusion crust were separated from ALH 84001,97. The C-14 terrestrial age is 6.5 +/- 1.3 k.y. The noble gas exposure age is reported to be 14 +/- 2 m.y. The Be-10 and Cl-36 concentrations in three subsamples are nearly constant. A reasonable interpretation is that there are no SCR (solar cosmic ray) effects at these sample depths. The Be-10 production rate is estimated to be 21-24 atom/min-kg based on recovered size and over 3 cm of ablation depth. The Be-10 concentration indicates that ALH 84001 was exposed to cosmic rays 4-7 m.y. in a 4 pi geometry. The Be-10 exposure age is significantly shorter than noble gas exposure age. Three of the subsamples of ALHA 77005 measured for cosmogenic radionuclides are aliquots from the noble gas study. Chemical analysis and Al-26 measurements for these three subsamples are in progress.
Caffee Marc W.
Finkel Robert C.
Nishiizumi Kuni
No associations
LandOfFree
Exposure histories of ALH 84001 and ALHA 77005 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Exposure histories of ALH 84001 and ALHA 77005, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exposure histories of ALH 84001 and ALHA 77005 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-822400