Accretion of interplanetary dust in polar ice
2000
Brook, Edward J. | Kurz, Mark D. | Curtice, Joshua | Cowburn, Stuart
Measurements of helium isotopes in particles separated from polar ice demonstrate that extraterrestrial ³He dominates the ³He flux at the GISP2 (Greenland) and Vostok (Antarctica) ice core sites. Replicate measurements of late Holocene ice samples yield ³He fluxes of 0.62±0.27×10⁻¹² cm³ STP cm⁻² ka⁻¹ (GISP2) and 0.77 ± 0.25 × 10⁻¹² cm³ STP cm⁻² ka⁻¹ (Vostok), similar to results from marine sediments. These are the first detailed measurements of ³He in particles from ice core samples, and they demonstrate the utility of the ice core record for evaluating the temporal history of the extraterrestrial dust flux. Results from Vostok samples from 1096–1403 m depth (75–97 ka B.P.) are similar to the late Holocene data, with the exception of two highly anomalous results from 1307 m. The latter probably indicate the presence of rare, large or gas‐rich extraterrestrial particles.
Показать больше [+] Меньше [-]We thank the National Science Foundation(OPP-9909384, OPP-9909663, and EAR-9807951) and NASA (NAG5-9345) for support.
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