Experimental Investigations on the Role of H20 in Magmatic Processes

拟议的实验将提供水对地幔熔融和地壳分异过程的影响的限制。这些研究将提供关于熔化和分步结晶的温度、挥发物含量和压力的资料。 水在地球内部的循环对于理解地质时期地球的化学演化具有根本的重要性。 固液分异（地壳形成、地幔分异和地核分离）、海洋起源和地球生命起源的过程都与H2O在地球内部深处的循环有关。 提出了三个项目。1)水对天然玄武岩熔体液相线影响的系统研究。 这些实验将提供定量的信息，可用于模拟的H2O不饱和熔融的硅酸盐中存在的变量的H2O，并应有助于解决相当大的不确定性的影响，少量的H2O熔融。 2)H_2O、压力和地幔成分对橄榄岩熔融作用的研究 这些实验将提供H2O和整体成分（主要是碱金属元素Na 2 O和K2 O）对俯冲带和陆下地幔环境中岩浆生成所起作用的定量估计。 3)水和压力对地壳中玄武岩熔体分离结晶作用的实验研究。 在弧岩浆系统中，分异弧岩浆的成分特征及其矿物组合可以提供喷发前分异的H2O含量、温度和深度历史的证据。 对于所有的前面的研究，我们将开发基于化学的分析模型，允许预测的熔化/结晶的条件和组成时产生的熔体H2O参与。这些研究将对H2O对地壳和地幔化学演化的影响进行定量限制。这一关于H2O的信息将引起地球动力学和矿物物理学界的广泛兴趣，并最终与地球海洋和地球生命的起源有关。 本项目将对研究生和本科生进行实验岩石学/地球化学研究方法的培训。从这项研究中得到的实验数据将与社区共享，并将开发和分发用于预测熔融/结晶温度，H2O含量和压力的模型。

The proposed experiments will provide constraints on the influence of water on mantle melting and on crustal differentiation processes. The studies will provide information on the temperature, volatile content and pressure of melting and fractional crystallization. The cycling of water through the Earth's interior is of fundamental importance for understanding the chemical evolution of the Earth over geologic time. Processes of solid - liquid differentiation (crust formation, mantle differentiation and core segregation), of the origin of the oceans and of life on Earth are tied to the cycling of H2O through our planet's deep interior. Three projects are proposed. 1) A systematic investigation of the influence of H2O on the liquidus of natural basaltic melts. These experiments will provide quantitative information that can be used to model the H2O-undersaturated melting of silicates in the presence of variable amounts of H2O, and should help resolve the considerable uncertainty on the influence of small amounts of H2O on melting. 2) Investigation of the role of H2O, pressure and mantle composition on peridotite melting. These experiments will provide quantitative estimates of the role played by H2O and bulk composition (primarily the alkali elements Na2O and K2O) on the generation of magmas in subduction zone and sub continental mantle environments. 3) Experimental studies of the role of H2O and pressure on fractional crystallization of basaltic melts in the crust. In arc magmatic systems the compositional characteristics of differentiated arc magmas and their mineral assemblages can provide evidence of the pre-eruptive H2O content, temperature and depth history of differentiation. For all of the preceding studies we will develop thermodynamically based analytic models that allow prediction of conditions of melting/crystallization and compositions of melts generated when H2O is involved. These studies will place quantitative constraints on the influence of H2O on the chemical evolution of the Earth's crust and mantle. This information on H2O will be of broad interest in the geodynamics and mineral physics community and ultimately has relevance for the origin of the Earth's oceans and life on Earth. This project will train graduate and undergraduate students in research methods of experimental petrology/geochemistry. The experimental data that results from this study will be shared with the community and models for predicting temperature, H2O content and pressure of melting/crystallization will be developed and distributed.