Experiments on Hydrous Intermediate Magmas

安山岩熔岩和火山灰（52-63% SiO2）沿3.5万公里的全球火山弧系统喷发，这与大洋板块在海沟的俯冲有关。这种物质含有水，代表了水从地幔到地壳和地表的主要回流通量之一。因此，估算中间岩浆中的水浓度是一个一级问题，因为它不仅影响安山岩源区的熔融条件，以及结晶相的顺序和变化（岩浆在上升过程中减压），而且是对爆发火山作用的基本控制之一。此外，弧相关岩浆中水量的限制影响了全球水收支，以及与岩浆活动释放的水相比，是否有更多的水被俯冲。该项目将评估墨西哥安山岩岩浆在整个组成范围内的水浓度，并将为安山岩岩浆中水的溶解度提供一个基于热力学的表达式，作为压力、温度和组成的函数。

CarmichaelEAR-0228919Andesitic lava and ash (52-63% SiO2) erupts along the 35,000 km global volcanic arc system, which is associated with the subduction of an oceanic plate at an oceanic trench. This material contains water and represents one of the principal return fluxes of water from the earth's mantle to the crust and to the surface. Thus estimating the concentration of water in intermediate magma is a first order problem, as it not only affects the conditions of melting in the andesite source region, as well as the order and variety of the crystalline phases (as the magmas decompress on ascent), but it also is one of the fundamental controls on explosive volcanism. Moreover constraints on the amount of water in arc related magmas affects the global water budget and the question of whether more water is being subducted in comparison to that released by magmatism. This project will assess the concentration of water in Mexican andesitic magmas over a wide whole composition range, and will provide a thermodynamically based expression for the solubility of water in andesitic magma as a function of pressure, temperature and composition.