The 410,000 Year Terrestrial Age of Eucrite Río Cuarto 001

J. LEVINE; A. ARAZI; T. FAESTERMANN; J.O. FERNÁNDEZ NIELLO; G. KORSCHINEK; A.M. LA GAMMA; A. NEGRI; G. RUGEL; P. STEIER; A. WALLNER

METEORITICS & PLANETARY SCIENCE

The University of Arizona

Lugar: Tucson; Año: 2008 vol. 43 p. 805 - 813

1086-9379

We have measured a surprisingly long terrestrial age of  410, 000 +45,000-20,000 years(410 +45-20 ka) for basaltic eucrite Río Cuarto 001 using accelerator mass spectrometry of26Al, 36Cl, and 41Ca. Though many meteorites are known to have survived for tens orhundreds of ka in Antarctica or hot deserts, the mean annual precipitation of 815 mm inRío Cuarto, Cordoba Province, Argentina, makes the long survival of this meteoriteremarkable. We propose two explanations for the exceptional preservation of Río Cuarto001. First, the meteorite contains only trace amounts of metal, so the weathering andoxidation 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 beenexhumed only recently from beneath a protective layer of soil. Insofar as the survival onEarth of Río Cuarto 001 is due to environmental factors, there may be other meteoriteswith comparably long terrestrial ages still to be discovered in the vicinity.