Ultrasonic Velocity Measurements on Silicate Liquids

该提案的主要目标是使用超声波干涉仪在宽温度范围内测量各种硅酸盐液体的零压压缩率。 我们的高温能力将用于：（1）在1600摄氏度以下（例如，英安岩和流纹岩），（2）进入具有特别高的液相线温度的熔体（例如，过铝熔体、科马提岩、橄榄岩），以及（3）通过在跨越几百度的温度间隔上测量松弛声速来改善对熔体可压缩性的温度依赖性的约束。 此外，实验计划检查硅酸盐熔体的压缩性的变化进行组合物诱导的阳离子（Al 3+，Fe 3+，Ti 4+）的配位变化在一巴。 这些实验将为理解压力诱导的阳离子配位变化对熔体密度的影响提供类比。 最后一个应用是含有挥发性成分（氟和磷）的硅酸盐熔体和各种碳酸盐液体。 所有拟议的零压力（1巴）下的声速测量将为现场方法提供重要补充，这些方法允许在压力下导出密度和压缩性。

LangeEAR-0087764The primary goal of this proposal is to measure the zero pressure compressibility of a variety of silicate liquids over a wide temperature range using an ultrasonic acoustic interferometer. Our high-temperature capability will be used to: (1) obtain relaxed sound speeds on liquids that are too viscous for such measurements below 1600 degrees C (e.g., dacite and rhyolite), (2) access melts with exceptionally high liquidus temperatures (e.g., peraluminous melts, komatiite, peridotite), and (3) improve constraints on the temperature dependence of melt compressibility by measuring relaxed sound speeds over temperature intervals that span several hundred degrees. In addition, experiments are planned to examine variations in the compressibility of silicate melts undergoing composition-induced coordination change of cations (Al3+, Fe3+, Ti4+) at one bar. These experiments will provide analogies for understanding the consequences of pressure-induced coordination change of cations on melt density. A final application is to silicate melts containing volatile components (fluorine and phosphorous) and a variety of carbonatite liquids. All of the proposed sound speed measurements at zero pressure (one bar) will provide a critical complement to in-situ methods that allow density and compressibility to be derived at pressure.