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Minor- and trace-element sector zoning in synthetic enstatite

Craig S. Schwandt and Gordon A. McKay
Minor- and trace-element sector zoning in synthetic enstatite (in Planetary materials; from the Earth to the Moon and beyond; Jim Papike special issue, Charles Shearer (prefacer), David Vaniman (prefacer) and Ted Labotka (prefacer))
American Mineralogist (October 2006) 91 (10): 1607-1615

Abstract

Minor- and trace-element sector zoning is nearly ubiquitous in pyroxene grown from basaltic melts using 1 atm gas-mixing furnaces. Mineral/melt partition coefficients can differ between sectors by more than a factor of five. A synthesized hypersthene-normative basalt composition was doped with Al, Cr, and Ti using a matrix of doping experiments, to understand better the mechanisms behind the formation of sector zoning. Isothermal and controlled-cooling experiments were conducted. The {010} sectors contain higher enrichments of Al, Cr, and Ti than {100} sectors, at the expense of Mg and Si. Evaluation of these relative sector enrichments indicates that sector zoning results from several kinetic mechanisms, which exert influence even when attempting laboratory conditions that approximate equilibrium: (1) rapid growth rate, not necessarily synonymous with rapid cooling; (2) crystal-chemical control by means of charge-coupled substitutions; and (3) diffusion limitations of Si tetrahedra in the melt boundary layers respective to the different crystal faces.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 91
Serial Issue: 10
Title: Minor- and trace-element sector zoning in synthetic enstatite
Title: Planetary materials; from the Earth to the Moon and beyond; Jim Papike special issue
Author(s): Schwandt, Craig S.McKay, Gordon A.
Author(s): Shearer, Charlesprefacer
Author(s): Vaniman, Davidprefacer
Author(s): Labotka, Tedprefacer
Affiliation: Jacobs/ESCG, Houston, TX, United States
Affiliation: University of New Mexico, Institute of Meteoritics, Albuquerque, NM, United States
Pages: 1607-1615
Published: 200610
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 24
Accession Number: 2006-091235
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. table
Secondary Affiliation: Los Alamos National Laboratory, USA, United StatesUniversity of Tennessee, USA, United StatesNASA, Johnson Space Center, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200650
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