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Evidence for a very high carbon/iridium ratio in the Tunguska impactor
Author(s) -
RASMUSSEN Kaare L.,
OLSEN Hans J. F.,
GWOZDZ Raymond,
KOLESNIKOV Euginev M.
Publication year - 1999
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.1999.tb01407.x
Subject(s) - iridium , deposition (geology) , geology , peat , carbon fibers , mineralogy , geochemistry , cosmic ray , astrobiology , analytical chemistry (journal) , chemistry , astrophysics , physics , materials science , environmental chemistry , geomorphology , composite material , archaeology , biochemistry , sediment , composite number , catalysis , history
— We have measured excess Ir and depletion of 14 C, two independent indicators of cosmic material, in peat cores from the central Tunguska impact site. Both Ir and 14 C show pronounced anomalies in the same stratigraphical depth interval. We have estimated an integral deposition of nonradioactive cosmogenic C of 6.8 ± 1.0 mg C cm −2 , and an integrated Ir deposition of 5.9 ± 1.2 pg Ir cm −2 . The very high C/Ir ratio and a deduced δ 13 C value of +55 ± 10% relative to V Pee Dee Belemnite (VPDB) of the impactor material found in this study points towards a cometary type impactor, rather than a chondritic or achondritic asteroidal type impactor.