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Petrology of some oceanic island basalts: PRIMELT2.XLS software for primary magma calculation
 

Summary: Petrology of some oceanic island basalts: PRIMELT2.XLS
software for primary magma calculation
C. Herzberg
Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA (herzberg@rci.rutgers.edu)
P. D. Asimow
Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
[1] PRIMELT2.XLS software is introduced for calculating primary magma composition and mantle
potential temperature (TP) from an observed lava composition. It is an upgrade over a previous version in
that it includes garnet peridotite melting and it detects complexities that can lead to overestimates in TP by
>100°C. These are variations in source lithology, source volatile content, source oxidation state, and
clinopyroxene fractionation. Nevertheless, application of PRIMELT2.XLS to lavas from a wide range of
oceanic islands reveals no evidence that volatile-enrichment and source fertility are sufficient to produce
them. All are associated with thermal anomalies, and this appears to be a prerequisite for their formation.
For the ocean islands considered in this work, TP maxima are typically $1450­1500°C in the Atlantic and
1500­1600°C in the Pacific, substantially greater than $1350°C for ambient mantle. Lavas from the
Gala´pagos Islands and Hawaii record in their geochemistry high TP maxima and large ranges in both TP
and melt fraction over short horizontal distances, a result that is predicted by the mantle plume model.
Components: 14,488 words, 12 figures, 1 table.
Keywords: mantle plumes; oceanic island basalts; mantle potential temperature; primary magma.
Index Terms: 3621 Mineralogy and Petrology: Mantle processes (1038); 3610 Mineralogy and Petrology: Geochemical

  

Source: Asimow, Paul D. - Division of Geological and Planetary Sciences, California Institute of Technology,
Hewins, Roger H.- Department of Earth and Planetary Sciences, Rutgers University

 

Collections: Geosciences