A nebular origin for chondritic fine-grained phyllosilicates

Science

Volumn 299, Issue 5606, 2003, Pages 549-552

  Ciesla, Fred J ^a   Lauretta, Dante S ^a   Cohen, Barbara A ^b   Hood, Lon L ^a  

^a UNIVERSITY OF ARIZONA   (United States)

^b UNIVERSITY OF HAWAII   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICAL REACTIONS; HYDRATION; SHOCK WAVES;

SOLAR NEBULA;

SILICATES;

MINERAL; SILICATE;

CHONDRITE; HYDRATION; PHYLLOSILICATE; SOLAR SYSTEM;

ARTICLE; ASTRONOMY; CHEMICAL REACTION; COOLING; GAS; HYDRATION; METEOROLOGY; MODEL; POLYMERIZATION; PRIORITY JOURNAL; SHOCK WAVE; SOLID; TEMPERATURE;

ICE; METEOROIDS; PRESSURE; SILICATES; TEMPERATURE; THERMODYNAMICS; WATER;

EID: 0037462507     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1079427     Document Type: Article

References (31)

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22. Thermodynamic equilibrium calculations were performed with the use of the equilibrium module in the HSC Chemistry v5.0 software package, produced by Outokumpu Research Oy (Pori, Finland). This module calculates multicomponent equilibrium compositions in heterogeneous systems with the use of a database of over 15,000 compounds and a Gibbs energy minimization equilibrium solver. The system is composed of H, He, C, N, O, Mg, Si, S, and Fe. The abundances of all elements except H and O are set at solar system abundances (23). The abundances of H and O are enhanced consistent with an ice abundance of 700x solar. The species considered in the calculations included 127 different gaseous molecules as well as Fe metal, forsterite, fayalite, enstatite, ferrosilite, troilite, chrysotile, greenalite, wustite, magnetite, hematite, brucite, Fe(II) hydroxide, Fe(III) hydroxide, graphite, SiC, cohenite, siderite, magnesite, sinoite, and water ice. Thermodynamic data for cronstedtite, the most abundant Febearing phase in phyllosilicate-rich accretionary rims, are not available. However, a thermodynamic model for greenalite, a mineral similar in composition and structure to cronstedtite, was recently developed (24), and we use this phase to represent Fe-bearing phyllosilicate material. Thermodynamic data for all other species are included in the software database.
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31. The authors thank H. Connolly, J. Nuth, and two anonymous reviewers for useful discussions and comments and M. Pasek for help in carrying out the equilibrium calculations. Supported by a grant from the NASA Origins program. This is Hawaii Institute of Geophysics and Planetology publication no. 1253 and School of Ocean and Earth Science Technology publication no, 6076.