Olivine melt inclusions

A melt inclusion and its olivine host are concentric spheres of radius R- and / 2. Consider H2O in the melt inclusion and its re-equilibration with ambient melt outside olivine. Ignore anisotropy of olivine. If / i=0.1mm, / 2 = 1 mm, H2O diffusivity in olivine is D = 10 " m /s, K=0.000, find the reequilibration timescale. 

Consider Ca in a basaltic melt inclusion concentric with the host mineral olivine. The radius of the inclusion is SOfim. The olivine radius is 1 mm. The Ca partition... 

Chassigny is the only known martian dunite. It is an olivine-chromite cumulate consisting of 90% olivine (Fa. 32), 5% pyroxene, 2% feldspar (An 2o) that has been transformed into maskelynite, and 3% accessory minerals including chromite (Figure 30(d)). Melt inclusions in olivine contain hydrous amphibole. 

Goodrich C. A., Fioretti A. M., Tribaudino M., and Molin G. (2001) Primary trapped melt inclusions in olivine in the ohvine-augite-orthopyroxene ureihte Hughes 009. Geochim. Cosmochim. Acta 65, 621 —652. 

Brachinites consist dominantly of olivine, 79-93%, and all contain high-calcium pyroxene, 3-15%. Only some contain plagioclase— ALH 84025, Eagles Nest, and NWA 595 are plagioclase-free, while the remainder contain from a trace up to 9.9% for Brachina. Orthopyroxene is absent or at trace levels in most, but Hughes 026 contains 1.6%, while NWA 595 reportedly contains 10-15% orthopyroxene. Brachina contains orthopyroxene only in melt inclusions in olivine (Nehru et al., 1983). Chromite and iron-sulfide are minor... 

Shimizu N., Sobolev A. V., Layne G. D., and Tsameryan O. P. (2003) Large Pb isotope variations in olivine-hosted melt inclusions in a basalt fromt the Mid-Atlantic Ridge. Science (ms. submitted May 2003). 

Sisson and Layne (1993) analyzed melt inclusions in olivines in samples from four arc volcanoes. Inclusions in olivines in basalts from the 1974 eruption of Fuego volcano, Guatemala, contain 2.1-4.6 wt.% H2O. Inclusions in olivines in basaltic andesites from the same eruption have a wider range, from 1.0 wt.% to 6.2 wt.% H2O. Inclusions hosted in olivines in basalts from three centers in the Southern Cascades have lower water contents, ranging from 0.2 wt.% to 1.4 wt.%H20. 

Sobolev and Chaussidon (1996) summarize an extensive body of data on olivine-hosted melt inclusions from basalts from a variety of tectonic settings. They concentrated on inclusions hosted in magnesium-rich olivines, with the... 

Kamenetsky V. S., Sobolev A. V., Eggins S. M., Crawford A. J., and Arculus R. J. (2002) Olivine-enriched melt inclusions in chromites from low-Ca boninites, Cape Vogel, Papua New Guinea evidence for ultramafic primary magma, refractory mantle source and enriched components. Chem. Geol. 183, 287-303. 

Massare D., Metrich N., and Clocchiatti R. (2002) High-temperature experiments on silicate melt inclusions in olivine at 1 atm inferences on temperatures of homogenization and H2O concentrations. Chem. Geol. 

Shimizu N. and Sobolev A. (1998) In-situ Pb isotopic analysis of olivine-hosted melt inclusions from mid-ocean ridges. EOS Trans, 79, f790. 

Note that it is particularly difficult to quantify pre-emptive volatile contents of andesites because most are empted subaerially (i.e., at atmospheric pressure) after significant degassing has taken place, and contain abundant phenocrysts (e.g., >30 wt.%) such that liquid compositions are more silicic (often rhyolitic) than bulk rock. Also, good host minerals for melt inclusions (e.g., olivine and quartz) are rare, and mineral disequilibria hamper experimental work. 

Danyushevsky L. V., Sokolov S., and Falloon T. J. (2002) Melt inclusions in olivine phenocrysts using diffusive reequilibration to determine the cooling history of a crystal, with implications for the origin of oUvine-phyric volcanic rocks. J. Petrol. 43, 1651—1671. 

Jambon A., Lussiez P., Clocchiatti R., Weisz J., and Hernandez J. (1992) Olivine growth rates in a tholeiitic basalt-an experimental study of melt inclusions in plagioclase. Chem. Geol. 96, 277-287. 

Shimizu N. (1998) The geochemistry of olivine-hosted melt inclusions in a FAMOUS basalt ALV519-4-1. Phys. Earth Planet. Inter. 107, 183-201. 

Shimizu N. and Grove T. L. (1998) Geochemical studies of olivine-hosted melt inclusions from ridges and arcs. EOS, Trans., AGU 79, F1002. 

Mafic minerals contained in volcanic rocks (phenocrysts) or in xenoliths are widely exploited in noble gas studies as they frequently contain fluid and/or melt inclusions that trap noble gases. Olivines and pyroxenes are the most commonly utilized minerals. Whole-rock samples are first crushed to 0.5 to 2 mm or larger, depending on the size of the crystals. The olivines and pyroxenes are then separated using a Frantz-Isodynamic magnet separator, followed by hand-picking under a binocular microscope to remove any... 

Michael PJ (1988) Partition coefficients for rare earth elements in mafic minerals of high silica rhyohtes the importance of accessory mineral inclusions. Geochim Cosmochim Acta 52 275-282 Mysen BO (1979) Nickel partitioning between olivine and silicate melt Henry s Law revisited. Am Mineral 64 1107-1114... 

The winonaites are compositionally similar to silicate inclusions in some IAB irons (described below). They have chondritic compositions, and relict chondrules have been found in some meteorites. They consist of olivine, pyroxenes, plagioclase, metal, troilite, and other minor minerals (Benedix et al., 1998), and most have been recrystallized. Like the acapulcoites, they have experienced only small degrees of melting. 

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