Minor and trace element partitioning between pyroxene and melt in rapidly cooled chondrules

Journal Article · Thu May 01 04:00:00 EDT 1997 · American Mineralogist

DOI:https://doi.org/10.2138/am-1997-5-613· OSTI ID:543158

Jones, R H ^[1]; Layne, G D ^[1]

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1. Univ. of New Mexico, Albuquerque, NM (United States)

We present minor and trace element (REE, Sr, Y, and Zr) data for pyroxenes and mesostases in four porphyritic chondrules from the Semarkona ordinary chondrite. Apparent partition coefficients for clinoenstatite, orthoenstatite, pigeonite, and augite are compared with experimental and petrologic data from the literature, and the effects on apparent partition coefficients of the rapid cooling rates at which chondrules crystallized are evaluated. For most elements, the effects of cooling at rates of hundreds of degrees per hour cannot be distinguished from variations in equilibrium data resulting from differences in temperature or composition. However, for LREE apparent partition coefficients are significantly higher than comparable equilibrium data, and the ratio of HREE/LREE partition coefficients is lower, particularly for Ca-poor pyroxene. We attribute this flattening of REE patterns to the effect of rapid cooling. Apparent partition coefficients of all REE and Y in augite are higher than equilibrium data, particularly in one chondrule with a high ALO, content. We suggest that this may be attributed to an increase in the uptake of trivalent trace element cations in the pyroxene crystal structure as a result of charge-balanced substitutions with API cations. 32 refs., 6 figs., 3 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 543158
• Journal Information: American Mineralogist, Journal Name: American Mineralogist Journal Issue: 5-6 Vol. 82; ISSN 0003-004X; ISSN AMMIAY
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
58 GEOSCIENCES
ABUNDANCE
CHONDRITES
ELEMENTS
GEOCHEMISTRY
MINERALOGY
RARE EARTHS
STONE METEORITES
TRACE AMOUNTS