干旱区生态环境知识资源中心

We have measured a surprisingly long terrestrial age of 410,000 +/- (45,000) (20,000) yr (410 +/- (20)(45) ka) for basaltic eucrite Rio Cuarto 001 using accelerator mass spectrometry of (26)Al, (36)Cl, and (41)Ca. Though many meteorites are known to have Survived for tens or hundreds of ka in Antarctica or hot deserts, the mean annual precipitation of 815 mm in Rio Cuarto, Cordoba Province, Argentina, makes the long survival of this meteorite remarkable. We propose two explanations for the exceptional preservation of Rio Cuarto 001. First, the meteorite contains only trace amounts of metal, so the weathering and oxidation of metallic Fe, which commonly destroys chondrites, is ineffective in this case. Second, the meteorite was found in a relatively young deflation basin, and may have been exhumed only recently from beneath a protective layer of soil. Insofar as the Survival oil Earth of Rio Cuarto 001 is due to environmental factors, there may be other meteorites with comparably long terrestrial ages still to be discovered in the vicinity.