TY - JOUR
T1 - Micrometeorites in Antarctic ice detected by Ir
T2 - Estimation of 120k year old accretion rate
AU - Miura, A.
AU - Saito, Y.
AU - Tazawa, Y.
AU - Fukuoka, T.
AU - Noguchi, T.
AU - Motoyama, H.
N1 - Funding Information:
Acknowledgments Authors thank Ms. H. Kusuno for drawing figure and typing manuscript. Authors thank also Dr. T. Hasenaka for review of English. Frey counting system were maintained by Ms. K. Nagata. This work has been supported by the Institute-University Laboratory for Joint use of JAEA Facilities, and also by the Institute for Cosmic Ray Research, University of Tokyo. We thank Japan Antarctic Research Expedition Team working at Dome Fuji for providing the samples in this work.
PY - 2012/1
Y1 - 2012/1
N2 - The accretion rate of micrometeorites (MMs) was estimated from Ir contents in snow around Dome Fuji Station and ice shards obtained during ice core drilling at Dome Fuji Station, Antarctica. The snow and ice shards were melted and filtered from the residues. Although MMs were not found on filters, we tried to detect them from the residues as Ir peaks determined by instrumental neutron activation analysis (INAA). Although Ir is very rare in the earth's crust, its concentration is high in extraterrestrial matter (e.g., chondrites). Trace amounts of Ir can be easily detected by INAA, because the cross section of Ir is relatively large (e.g., 309 barn). The accretion rates were estimated for 120k year ago, 5k year ago and at present, as (3.2 ± 0.9)× 102 t/year (8.6 ± 0.18) × 103 t/year and (1.3 ± 0.10) × 103 t/year, respectively. These estimates were comparable to those of previous studies, however the rate of 120k year ago was approximately an order of magnitudes lower than the others.
AB - The accretion rate of micrometeorites (MMs) was estimated from Ir contents in snow around Dome Fuji Station and ice shards obtained during ice core drilling at Dome Fuji Station, Antarctica. The snow and ice shards were melted and filtered from the residues. Although MMs were not found on filters, we tried to detect them from the residues as Ir peaks determined by instrumental neutron activation analysis (INAA). Although Ir is very rare in the earth's crust, its concentration is high in extraterrestrial matter (e.g., chondrites). Trace amounts of Ir can be easily detected by INAA, because the cross section of Ir is relatively large (e.g., 309 barn). The accretion rates were estimated for 120k year ago, 5k year ago and at present, as (3.2 ± 0.9)× 102 t/year (8.6 ± 0.18) × 103 t/year and (1.3 ± 0.10) × 103 t/year, respectively. These estimates were comparable to those of previous studies, however the rate of 120k year ago was approximately an order of magnitudes lower than the others.
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U2 - 10.1007/s10967-011-1312-7
DO - 10.1007/s10967-011-1312-7
M3 - Article
AN - SCOPUS:84863484680
SN - 0236-5731
VL - 291
SP - 213
EP - 216
JO - Journal of Radioanalytical and Nuclear Chemistry
JF - Journal of Radioanalytical and Nuclear Chemistry
IS - 1
ER -
