Origin of mantle peridotite and komatiite by partial melting

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doi: 10.1029/GL012i009p00541
Authors:Herzberg, C. T.; O'Hara, M. J.
Author Affiliations:Primary:
Rutgers Univ., Dep. Geol. Sci., New Brunswick, NJ, United States
Other:
Univ. Coll. Wales, United Kingdom
Volume Title:Geophysical Research Letters
Source:Geophysical Research Letters, 12(9), p.541-544. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276
Publication Date:1985
Note:In English. 22 refs.; illus.
Summary:Theoretical calculations and some preliminary experimental observations show that the liquidus and solidus temperatures for each of a wide range of upper mantle peridotite and komatiite compositions become coherent at high pressures. This suggests that these materials may have been liquids in eutectic-like equilibrium (rather than peritectic-like) with mantle assemblages. It is shown that the major element geochemistry of 83 mantle peridotites and 61 komatiites define a trend which is not primarily due to an olivine control process; rather it is interpreted to represent the pressure-induced compositional trace of eutectic liquids in equilibrium with mantle assemblages from 4 to 15 GPa. If the bulk Earth is chondritic in composition these phase equilibrium constraints would imply that the upper mantle had formed from the whole mantle as an ultrabasic partial melt, the transition zone and lower mantle being the complementary eclogite and pyroxenite residua. This is consistent with mineralogical interpretations of seismic data for the present-day Earth which call for a peridotite upper mantle and pyroxene-like transition zone and lower mantle. [C.N.]
Subjects:Chemical composition; Experimental studies; Genesis; Geophysics; High pressure; Igneous rocks; Komatiite; Liquid phase; Mantle; Partial melting; Peridotites; Phase equilibria; Plutonic rocks; Pressure; Processes; Solid phase; Theoretical studies; Ultramafic composition; Ultramafics; Upper mantle; Volcanic rocks
Abstract Numbers:87M/4136
Record ID:1985080310
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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