Update on terrestrial ages of Antarctic meteorites

Conference · Fri Jan 14 04:00:00 EST 2000

OSTI ID:756734

Welten, K C ^[1]; Nishiizumi, K; Caffee, M W

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1. LLNL

Terrestrial ages of Antarctic meteorites are one of the few parameters that will help us to understand the meteorite concentration mechanism on blue-ice fields. Traditionally, terrestrial ages were determined on the basis of {sup 36}Cl in the metal phase, which has an uncertainty of about 70 ky. For young meteorites (< 40 ky), the terrestrial age is usually and most accurately determined using {sup 14}C in the stone phase. In recent years two methods have been developed which are independent of shielding effects, the {sup 10}Be-{sup 36}Cl/{sup 10}Be method and the {sup 41}Ca/{sup 36}Cl method. These methods have reduced the typical uncertainties in terrestrial ages by a factor of 2, to about 30 ky. The {sup 10}Be-{sup 36}Cl/{sup 10}Be method is quite dependent on the exposure age, which is unknown for most Antarctic meteorites. The authors therefore also attempt to use the relation between {sup 26}Al and {sup 36}Cl/{sup 26}Al to derive a terrestrial age less dependent on the exposure age. The authors have measured the concentrations of cosmogenic {sup 10}Be, {sup 26}Al and {sup 36}Cl in the metal phase of {approximately} 70 Antarctic meteorites, from more than 10 different ice-fields, including many new ones. They then discuss the trends in terrestrial ages of meteorites from different ice-fields.

• Research Organization: Lawrence Livermore National Lab., CA (US)
• Sponsoring Organization: USDOE Office of Defense Programs (DP) (US)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 756734
• Report Number(s): UCRL-JC-137138
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCURACY
AGE ESTIMATION
ANTARCTICA
BERYLLIUM 10
CALCIUM 41
CHLORINE 36
ISOTOPE DATING
METEORITES