Johnson, ""The role of volatile
exsolution and sub-solidus fluid/rock interactions in producing high 56Fe/54Fe ratios in siliceous igneous rocks," Geochimica et Cosmochimica Acta, vol.
Those from Thailand, Australia and Laos are known to have inclusions caused by
exsolution of hematite and ilmenite (Hughes, 1997, pp.
Petrology of the Lake George granodiorite stock, New Brunswick: implications for crystallization conditions, volatile
exsolution, and W-Mo-Au-Sb mineralization.
Thus, the Changfagou ore-forming fluid cannot have formed from direct exsolution from a magma.
Therefore, we conclude that the initial fluid formed via exsolution from a magma.
It is the expansion of the volatile phase following exsolution and magmatic fragmentation which produces the kinetic energy required to accelerate the magma-volatile mixture to the surface producing an explosive eruption.
This hypothesis is illustrated by a series of mathematical equations that Burnham (1983) used to model the energy released from the exsolution of water in rhyolitic magma.
(h) Chalcopyrite as emulsion droplet within sphalerite, making an
exsolution texture.
The compositions of coexisting magnetite and ilmenite can be used to estimate liquidus temperatures and oxygen fugacity (Andersen and Lindsley, 1988) of magmas, although subsolidus exsolution produces intergrowths that complicate application of the geothermometer/oxygen barometer in slowly cooled, coarse-grained rocks.
This, together with volatile exsolution, which creates buoyant magma, allows evolved magma to erupt.
