We have provided here a review of published literature showing the relevance of studies on olivine-hosted melt inclusions for determining the volatiles dissolved in magma and their evolution during magma ascent and decompression. Based on this, we summarize the following main points and raise some questions for future work: Olivine-hosted melt inclusions lead to pressure estimates that only rarely exceed 300-400 MPa, and provide a powerful tool for tracking degassing between these pressure and surface. Such a range of pressures is generally lower than those deduced from CO_2-rich fluid inclusions (Hansteen and Klugel 2008). This discrepancy raises an important question for future research. Presently, the volatile data for melt inclusions hosted in high pressure clinopyroxenes are very scarce, and these should be investigated further. Regarding olivine, its crystallization in basaltic magmas depends on temperature and the melt water content. Its growth rate is strongly influenced by the rate of decompression and undercooling and thus the conditions of magma ascent. Melt inclusion formation is favored by temperature and pressure gradients and undercooling. Olivine-hosted melt inclusions from rapidly cooled explosive products are the most suitable for avoiding extensive post-entrapment interaction between the inclusions and their host crystals. Data from such inclusions provide a rich record of dynamic processes. They allow us to infer the conditions of magma ascent, crystallization, and degassing. For future work, combining textural studies of natural and experimental olivines, their melt inclusion morphologies, and the dissolved volatile contents of the inclusions would allow a better estimate of the timescales of magma crystallization and ascent.
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