Zr/Nb systematics of Ocean Island basalts reassessed: The case for binary mixing

Kamber, B. S. and Collerson, K. D. (2000) Zr/Nb systematics of Ocean Island basalts reassessed: The case for binary mixing. Journal of Petrology, 41 7: 1007-1021. doi:10.1093/petrology/41.7.1007

Author Kamber, B. S.
Collerson, K. D.
Title Zr/Nb systematics of Ocean Island basalts reassessed: The case for binary mixing
Journal name Journal of Petrology   Check publisher's open access policy
ISSN 0022-3530
Publication date 2000-07-01
Sub-type Article (original research)
DOI 10.1093/petrology/41.7.1007
Volume 41
Issue 7
Start page 1007
End page 1021
Total pages 15
Editor M. Wilson
Place of publication Oxford, England, U. K.
Publisher Oxford University Press
Language eng
Subject C1
260102 Igneous and Metamorphic Petrology
780104 Earth sciences
Formatted abstract

  A survey of global ocean island basalt geochemistry shows a remarkably strong linear correlation (average r2 = 0·95) between Zr and Nb concentrations. Fractional crystallization explains neither the range in Zr and Nb concentrations nor the fact that regression lines have intercepts significantly different from zero. A substantial, linearly correlated (average r2 = 0·92) variability in Zr and Nb concentrations remains in the datasets after correction for fractional crystallization. Linear correlation between Zr and Nb concentrations is not expected from variable degrees of melting because the concentration of Nb is significantly more sensitive to the degree of melting than that of Zr. Our main conclusion is that the Zr/Nb systematics of ocean island basalts requires binary mixing, and more specifically mixing of two separate melts. We show that a mid-ocean ridge basalt melt is the depleted endmember, common to all examined ocean island basalts. The enriched endmember has a very variable Zr/Nb ratio. We speculate that, rather than implying the existence of several distinct enriched reservoirs, the highly variable Zr/Nb ratio could reflect intra-mantle processes such as fertilization by small-degree melts or carbonate–silicate melt immiscibility.

Keyword Geochemistry & Geophysics
Binary Mixing
Degree Of Melting
Fractional Crystallization
Linear Concentration Relationship
Trace Element Enrichment
Helium Isotope Systematics
Trace-element Constraints
Southern Indian-ocean
Carbonatite Metasomatism
Geochemical Evolution
Galapagos Archipelago
Silicate Perovskites
Lithospheric Mantle
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Earth Sciences Publications
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Created: Tue, 10 Jun 2008, 20:26:16 EST