Accession Number : AD0292913

Title :   CHLORINE 36 AND ARGON 39 IN METEORITES AND THE EXPOSURE AND TERRESTRIAL AGES OF IRON METEORITES

Corporate Author : MAX-PLANCK-INSTITUT FUER CHEMIE MAINZ (WEST GERMANY)

Personal Author(s) : VILCSEK,E. ; WANKE,H.

Report Date : DEC 1962

Pagination or Media Count : 1

Abstract : About 30 meteorites were analyzed. The decay rates of chlorine 36 varied between 0 and 28 dpm/kg; for argon 39, between 0 and 23 dpm/kg. Together with the argon 36 content we were able to calculate cosmic ray exposure ages of the meteorites analyzed. As already previously suspected, all the octahedrites, and mainly the medium octahedrites, show exposure ages of about 500 million years. Very large differences in the cosmic ray exposure ages were observed for the group of the hexahedrites. Problems about the orbits of the hexahedrites are discussed and special boundaries for their orbits were deduced from our measurements. It could be shown that the mean cosmic ray intensity during the last 300 years was the same as during the last 300,000 years. We looked for argon 39 in 21 different iron meteorites which were finds, and all of them, except Keen Mountain, showed no argon 39 activity. Lower limits for the terrestrial age between 1000 to 2000 years were calculated for these finds. For Keen Mountain meteorite the terrestrial age came out as about 1300 years. One meteorite, namely Tamarugal, showed also no chlorine 36 activity, indicating a terrestrial age of more than 1.5 million years. For Clark County meteorite we calculated a terrestrial age of 600,000 years. (Author)

Descriptors :   *METEORS, ARGON, CHLORINE, COSMIC RAYS, DEGRADATION, EXPOSURE(PHYSIOLOGY), INDEXES, PARTICLES

Distribution Statement : APPROVED FOR PUBLIC RELEASE