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Crystallization of Ca-Al-Rich Inclusions: Experimental Studies on the Effects of Repeated Heating EventsThe observed textures and chemistry of Ca-Al-rich inclusions (CAIs) are presumed to be the culmination of a series of repeated heating and cooling events in the early history of the solar nebula. We have examined the effects of these heating/cooling cycles experimentally on a bulk composition representing an average Type B Ca-Al-rich inclusion composition. We have tested the effect of the nature of the starting material. Although the most recent and/or highest temperature event prior to incorporation into the parent body dominates the texture and chemistry of the CAI, prior events also affect the phase compositions and textures. We have determined that heating precursor grains to about 1275 C prior to the final melting event increases the likelihood of anorthite crystallization in subsequent higher temperature events and a prior high temperature even that produced dendritic melilite results in melilite that shows evidence of rapid crystallization in subsequent lower temperature events. Prior low temperature pre-crystallization events produce final ran products with pyroxene compositions similar to Type B Ca-Al-rich inclusions, and the glass (residual liquid) composition is more anorthitic than any other experiments to date. The addition of Pt powder to the starting material appears to enhance the ability of anorthite to nucleate from this composition.
Document ID
20010071951
Acquisition Source
Johnson Space Center
Document Type
Preprint (Draft being sent to journal)
Authors
Paque, Julie M.
(Search for Extraterrestrial Intelligence Inst. Moffett Field, CA United States)
Lofgren, Gary E.
(NASA Johnson Space Center Houston, TX United States)
Le, Loan
(Lockheed Martin Corp. Houston, TX United States)
Date Acquired
August 20, 2013
Publication Date
January 6, 2000
Subject Category
Solid-State Physics
Funding Number(s)
PROJECT: RTOP 344-31-00-05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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