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The effect of [H.sub.2]O on olivine crystallization in MORB: experimental calibration at 200 MPa

Authors :
Almeev, Renat R.
Holtz, Francois
Koepke, Jurgen
Parat, Fleurice
Botcharnikov, Roman E.
Source :
American Mineralogist. April, 2007, Vol. 92 Issue 4, p670, 5 p.
Publication Year :
2007

Abstract

Crystallization experiments were conducted at 200 MPa and water-undersaturated conditions to quantify the effect of small amounts of [H.sub.2]O on the crystallization temperature of olivine in basaltic melts (e.g., Mid-Oceanic Ridge Basalts, MORB).The [H.sub.2]O concentrations in the quenched glasses, determined by infrared spectroscopy and Karl-Fischer-Titration, ranged between 0.25 and 4.2 wt% [H.sub.2]O. The dry liquidus temperature was estimated from experiments at 0.1 MPa ([H.sub.2]O-free) and from the known pressure dependence of olivine crystallization temperature. The liquidus temperature depression can be predicted by the empirical equation ([T.sup.DRY]-[T.sup.WET]) = 39.69*[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (wt%). The comparison of the experimental results with available crystallization models and empirical methods shows that most of the predicted liquidus temperature depressions differ significantly from that observed in this study. Keywords: Crystallization, [H.sub.2]O, MORB, olivine, liquidus, FTIR, KFT

Details

Language :
English
ISSN :
0003004X
Volume :
92
Issue :
4
Database :
Gale General OneFile
Journal :
American Mineralogist
Publication Type :
Academic Journal
Accession number :
edsgcl.162115060