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Iron and nickel isotopic mass fractionation in deep-sea spherulesMagnetite-wuestite spherules collected from deep-sea sediments are thought to have originally been Fe-Ni metal particles at the top of the atmosphere that were oxidized and melted during entry into the earth's atmosphere. Some likely sources for the metal particles are Fe-Ni interplanetary dust particles (IDP's) and metal or sulfide from stony IDP's that separated after melting. Davis et al. reported that four of these spherules are enriched in the heavy isotopes of iron, with enrichments of 8-23%/amu. We have developed a technique for analysis of both iron and nickel isotopes on the same ion microprobe spot and have applied this technique to a number of deep-sea spherules in order to better understand the processes leading to isotopic mass fractionation. Eight spherules show iron and nickel isotopic mass fractionation, with iron and nickel enriched in the heavy isotopes by 10-19%/amu and 4-32%/amu, respectively. If the mass fractionations are due to Rayleigh fractionation during evaporation, these spherules lost 76-94% of their original mass. We have analyzed the four magnetite-wuestite spherules for which iron isotopic data were reported by Davis et al. as well as four new spherules.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Davis, Andrew M.
(Chicago Univ. Chicago, IL, United States)
Brownlee, Donald E.
(Washington Univ. Seattle., United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F
Subject Category
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.

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