ABR: Experimental Studies of Hydrous Mantle Melting

这个项目的重点是了解地球？S地幔是如何在俯冲带熔融的。H2O是俯冲带岩浆形成的关键成分，俯冲带岩浆在弧形火山喷发，弧形火山形成于俯冲的大洋板块上方。这项研究将使用实验岩石学来了解当H2O参与熔融过程时岩浆是如何形成的。实验将包括熔融的岩石(地球？S地幔)，在水的存在下，温度和压力与火山链以下深处经历的温度和压力相同。关于H2O如何影响地幔熔融产生的温度和化学成分，人们知之甚少。通过了解水？S对这一岩浆生成过程的温度、熔体组成和化学反应的影响，我们将获得新的基础知识，即地球？S陆壳是在哪里以及如何通过地质时代生成的。这一新知识将推动基础科学的发展，为理解地球上45亿年来水的循环提供一个量化框架-S历史。这一基于成果的更新要求支持一项实验岩石学研究计划，该计划将量化水对俯冲带熔融过程的影响。这些实验将系统地研究(1)1.6~2.8 GPaH2O-不饱和地幔熔融；(2)1.2 GPa时深部地幔熔体与浅层地幔围岩的H2O-不饱和反应。在1.6-2.8 Gpa的压力范围内，人们对水合熔融的了解很少，因此这些实验将为在这个压力范围内的水合熔融过程提供新的信息。所提出的深部地幔熔体与浅层地幔围岩之间的反应实验将是有史以来第一次在0.5至2 Gpa的压力下进行的水合反应实验。这些实验将使人们能够定量地了解地幔楔形内部反应的影响，这一过程得到了广泛的认可，但目前还缺乏实验探索。在这两组实验中，目标都是评估H2O对熔体成分的影响，并使用新的数据来开发地幔熔融的定量模型以及弧下地幔中熔岩反应的模型。通过俯冲带中的地幔和地壳流动H2O的岩浆过程对于理解过去45亿年来地球的化学演化具有重要意义。这项拟议的工作将为理解水如何影响地球-S地幔和地壳的化学成分提供量化基础。这些实验数据将用于开发预测天然原始熔岩的温度、H2O含量和熔化压力的模型，并将与地球科学界共享。实验研究的结果还将有助于开发更好的软流圈地幔和俯冲板块之间的流动耦合的地球动力学模型，并对熔体通过地幔楔的物理传输过程提供约束。

This project focuses on understanding how the Earth?s mantle melts in subduction zones. H2O is a key ingredient in the formation of subduction zone magmas that erupt at arc volcanoes, volcanoes that form above subducted oceanic plates. This study will use experimental petrology to understand how magmas are formed when H2O is involved in the melting process. The experiments will consist of melting rock (the Earth?s mantle) in the presence of H2O at the temperatures and pressures equivalent to those experienced at depth below the volcanic chains. Very little is known about how H2O influences the temperature and chemical compositions produced by mantle melting. By understanding water?s influence on the temperature, melt composition and chemical reactions of this magma generation process, we will gain new fundamental knowledge of where and how the Earth?s continental crust has been generated through geologic time. This new knowledge will advance basic science by providing a quantitative framework for understanding the recycling of water through the Earth over the 4.5 billion years of our planet?s history.This Accomplishment Based Renewal requests support for a program of experimental petrology studies that will quantify the influence of water on melting processes in subduction zones. The experiments will systematically investigate (1) H2O-undersaturated mantle melting from 1.6 to 2.8 GPa and (2) H2O-undersaturated reaction of deeper mantle melts with shallower mantle wall rock at 1.2 GPa. Very little is known about hydrous melting in the pressure range of 1.6-2.8 GPa, so the experiments will provide new information on the process of hydrous melting in this pressure range. The proposed reaction experiments between deeper mantle melt and shallower mantle wall rock will be the first hydrous reaction experiments ever performed at pressures between 0.5 and 2 GPa. These experiments will allow a quantitative understanding of the effects of reaction within the mantle wedge, a process that is widely acknowledged but one that currently lacks experimental exploration. For both sets of experiments, the goal is to assess the influence of H2O on melt composition and to use the new data to develop quantitative models for mantle melting as well as models of melt-rock reaction in the sub-arc mantle. The magmatic processes that flux H2O through the mantle and crust in subduction zones are of fundamental importance for understanding the chemical evolution of the Earth over the last 4.5 billion years. The proposed work will provide a quantitative basis for understanding how H2O has influenced the chemical composition of the Earth?s mantle and crust. The experimental data will be used to develop models for predicting temperature, H2O content and pressure of melting for natural primitive lavas, which will be shared with the geosciences community. The results of the experimental study will also allow development of better geodynamic models of flow coupling between the asthenospheric mantle and the subducting slab, as well as providing constraints on the physical process of melt transport through the mantle wedge.