Iridium metal in chicxulub impact melt: Forensic chemistry on the K-T smoking gun

Science

Volumn 271, Issue 5255, 1996, Pages 1573-1576

  Schuraytz, Benjamin C ^a,b   Lindstrom, David J ^b   Marín, Luis E ^c   Martinez, René R ^d   Mittlefehldt, David W ^d   Sharpton, Virgil L ^a   Wentworth, Susan J ^d  

^a LUNAR AND PLANETARY INSTITUTE   (United States)

^b NASA JOHNSON SPACE CENTER   (United States)

^c UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO   (Mexico)

^d LOCKHEED MARTIN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

AGGREGATE; CRETACEOUS/TERTIARY BOUNDARY; IMPACT MELT; IRIDIUM; METEORITE;

MEXICO, YUCATAN, CHICXULUB CRATER;

EID: 0029772051     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.271.5255.1573     Document Type: Article

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36. -1 for 10 hours Analyses for 32 elements were obtained with the use of routine procedures of the Johnson Space Center INAA Laboratory [D. W. Mittlefehldt and M. M. Lindstrom, Geochim. Cosmochim. Acta 55, 77 (1991); D W Mittlefehldt, T.H See, F. Horz, Meteoritics 27, 361 (1992)].
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39. Subsplits of the melt rock powders, as well as those of the standards, were weighed to an accuracy of ± 0.02 mg and counted in the low-background Radiation Counting Laboratory at Johnson Space Center (32). In addition to Ir, abundances were obtained for Fe, Sc, Cr, Co, Ni, Sr, Ce, Eu, Tb, Hf, Th, and Zn. Because of uncertainties inherent in weighing small amounts of powder, particularly beyond the thirdgeneration splits (23), subsplit masses from the second generation onward were back-calculated by mass-balance normalization of the apparent Sc abundance for each subsplit to the mean Sc abundance of the five first-generation subsplits The subsplit masses were then used to convert all elemental masses into concentrations (32)
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55. We thank D. McKay, D. Morrison, G. Ryder, A Treiman, and two anonymous referees for constructive reviews, D. Rueb for darkroom expertise, and D. Steinberg Schuraytz for editonal assistance. This work was made possible in part by grants from the National Aeronautics and Space Administration Planetary Geology and Geophysics Program and the National Science Foundation Continental Dynamics Program, and was completed while B.C.S. held a National Research Council Associateship at Johnson Space Center. Lunar and Planetary Institute contribution 884.