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GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,
VOL. 9,
Q09001,
25 PP., 2008
doi:10.1029/2008GC002057 [Citation]
Petrology of some oceanic island basalts: PRIMELT2.XLS software for primary magma calculation
Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA
Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
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 ∼1450–1500°C in the Atlantic and 1500–1600°C in the Pacific, substantially greater than ∼1350°C for ambient mantle. Lavas from the Galápagos 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.
Received 10 April 2008; accepted 15 July 2008; published 18 September 2008.
Citation: (2008), Petrology of some oceanic island basalts: PRIMELT2.XLS software for primary magma calculation, Geochem. Geophys. Geosyst., 9, Q09001, doi:10.1029/2008GC002057.
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