Defining the Hydrous Petrogenetic Grid: Experimental Constraints on Primitive Hydrous Magmas

定义含水成岩网格：原始含水岩浆的实验约束

• 批准号: 0610005
• 负责人: Gordon Moore
• 金额: $ 30.05万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0610005&HistoricalAwards=false
• 关键词: Defining; Hydrous; Petrogenetic; Grid; Experimental

The study of volcanoes, including the processes in the earth that give rise to them, is an important part of earth sciences. This often awe-inspiring geologic process often disrupts human activity such as airline flights, and sometimes threatens the lives of the millions of people that live near volcanic centers. Therefore, there is much at stake that depends on our knowledge and understanding of this potentially deadly phenomenon. One important aspect of volcanoes that occur in arcs at destructive plate boundaries (known as subduction zones) is the role that volatile components such as H2O and CO2 play in the original melting of rock at high pressure and temperature. This melting process forms the magmas (molten rock and crystal mixtures) that are eventually erupted at the surface as lavas. It is well known that H2O and CO2 influence the initial melting temperature of the source rocks of volcanoes, determine the physical properties of the resulting magma (such as its density and viscosity), and fuel explosive eruptions (gas expansion). This project is focused on the influence of these volatile components on the chemistry of the melting process in the Earth's mantle. The knowledge gleaned from this project will help constrain the origins of the magmas that form volcanic arcs, their initial H2O and CO2 contents, and will contribute to our overall understanding of the processes that create volcanoes.The particular question that will be addressed by this experimental study is the influence of H2O on the silica activity of melts at mantle conditions. While it has been experimentally observed that mantle melts formed under hydrous conditions contain significantly higher silica contents, and melt at significantly lower temperatures, the fundamental relationships remain poorly constrained by experimental data. As a complement to existing constraints, this study will use experiments over a range of compositions (mafic to intermediate) to systematically measure how P, T, and variable fluid (H2O-CO2) composition influence the silica activity. The resulting data will enable a thermodynamic analysis showing the range of hydrous melts that could have been in equilibrium with the upper mantle, and thus will clarify the role (or the lack thereof) of H2O in the generation of primitive melts.

对火山的研究，包括引起它们的地球过程，是地球科学的重要组成部分。这种令人敬畏的地质过程通常会破坏人类活动，例如航空公司的航班，有时威胁着数百万居住在火山中心附近的人的生命。因此，有很多威胁要取决于我们对这种潜在致命现象的了解和理解。在破坏性板板边界（称为俯冲带）处发生的火山的一个重要方面是，在高压和温度下岩石的原始融化中，挥发性成分（如H2O和CO2）在岩石熔化中的作用。这种熔化的过程形成了岩浆（熔融岩石和晶体混合物），最终以熔岩的形式爆发。众所周知，H2O和CO2会影响火山源岩石岩的初始熔融温度，确定所得岩浆的物理特性（例如其密度和粘度），以及燃料爆炸性喷发（气体膨胀）。该项目的重点是这些挥发性成分对地球地幔熔化过程的化学反应的影响。该项目收集的知识将有助于限制形成火山弧的岩浆的起源，最初的H2O和CO2内容，并将有助于我们对创建火山的过程的整体理解。这项实验研究将解决的特定问题。这项实验研究将解决H2O对MELT在MELTS条件下的影响。虽然已经从实验上观察到，在含水条件下形成的地幔熔体含有明显较高的二氧化硅含量，并且在温度明显较低的情况下融化，但基本关系仍然受到实验数据的约束。作为对现有约束的补充，这项研究将使用一系列组成（镁铁质至中间）进行实验，以系统地测量P，T和可变液（H2O-CO2）组成如何影响二氧化硅活性。最终的数据将实现热力学分析，显示可能与上地幔平衡的液压熔体范围，因此将阐明H2O在原始熔体生成中的作用（或缺乏）。