Thermomagnetic analysis of meteorites, 3. C3 and C4 chondrites

Earth and Planetary Science Letters
By: , and 

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Abstract

Thermomagnetic analysis was made on samples of all known C3 and C4 chondrites in a controlled oxygen atmosphere. Considerable variation was noted in the occurrence of magnetic minerals, comparable to the variation observed earlier in the C2 chondrites. Magnetite was found as the only major magnetic phase in samples of only three C3 chondrites (2–4 wt.%) and the Karoonda C4 chondrite (7.7 wt.%). The magnetite content of these three C3 chondrites is only about one-third that observed in the C1 and C2 chondrites which were found to contain magnetite as the only magnetic phase. Five C3 chondrites were observed to undergo chemical change during heating, producing magnetite: this behavior is characteristic of troilite oxidation. Upper limits on initial magnetite content of about 1–9% were established for these meteorites. Samples of the remaining five C3 chondrites and the Coolidge C4 chondrite were found to contain both magnetite and metallic iron. In two samples, iron containing ≤2% Ni was observed, while in the other four, the iron contained 6–8 wt.% Ni. In addition to containing both magnetite and iron metal, three of these samples reacted during heating to form additional magnetite. Variations in the magnetic mineralogy and, hence by inference bulk mineralogy, of C3 and C4 chondrites indicate a more complex genesis than is evident from whole-rock elemental abundance patterns.

    Publication type Article
    Publication Subtype Journal Article
    Title Thermomagnetic analysis of meteorites, 3. C3 and C4 chondrites
    Series title Earth and Planetary Science Letters
    DOI 10.1016/0012-821X(76)90132-1
    Volume 29
    Issue 2
    Year Published 1976
    Language English
    Publisher Elsevier
    Description 8 p.
    First page 283
    Last page 290
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