Phase equilibrium constraints on angrite petrogenesis

Publication Status is "Submitted" Or "In Press: 
LDEO Publication: 
Publication Type: 
Year of Publication: 
1999
Authors: 
Editor: 
Journal Title: 
Geochimica Et Cosmochimica Acta
Journal Date: 
Feb
Place Published: 
Tertiary Title: 
Volume: 
63
Issue: 
3-4
Pages: 
573-585
Section / Start page: 
Publisher: 
ISBN Number: 
0016-7037
ISSN Number: 
Edition: 
Short Title: 
Accession Number: 
ISI:000080964900020
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Abstract: 

Parameterizations of liquidus boundaries and solid solution in the CMAS + Fe system (Shi, 1992) have been employed to depict the liquidus equilibria relevant to the petrogenesis of angrites, Angrites are basaltic achondrites characterized by highly aluminous augite (fassaite), intermediate Mg-Fe olivine, and late-stage CaFe-olivine (kirschsteinite). Two important features of the equilibria on the olivine liquidus surface relevant to angrite petrogenesis are: 1) the presence of a thermal divide on the of + aug + plag + liq boundary curve, which separates the compositions of source materials that produce low-silica angritic melts that crystallize highly aluminous augite from those that produce higher silica melts with tholeiitic to eucritic crystallization patterns; and 2) the change in the pseudo-invariant point on the low-silica side of the thermal divide from a plagioclase-peritectic involving spinel (ol + aug + plag + sp + liq) at high to intermediate Mg' (Mg/[Mg + Fe]) to two pseudo-eutectics involving kirschsteinite (ol + aug + plag + kir + liq and ol + kir + plag + sp + liq) at low Mg'.

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207ZDTimes Cited:12Cited References Count:35

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