Following the Water: H2O in Subducting Slabs and Mantle Wedges

追随水流：俯冲板片和地幔楔中的 H2O

• 批准号: 0208456
• 负责人: John Holloway
• 金额: $ 19.96万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208456&HistoricalAwards=false
• 关键词: Following; Water; H2O; Subducting; Slabs

Following the Water: H2O in Subducting Slabs and Mantle WedgesEAR-0208456PI: HollowayH2O (water) greatly influences many processes in the Earth. It is the most important factor in determining if a volcanic eruption will be explosive or not. The presence of small amounts of water in the minerals making up the Earth's mantle can weaken normally rigid minerals allowing the mantle to flow at geologically high velocities.In this project, we will conduct experiments at high temperatures and pressures to determine which hydrous minerals, if any, can be present in subducting oceanic crust, and at what depths those minerals dehydrate. Such dehydration ultimately results in the formation of water-rich magmas that often erupt very explosively.We also will do experiments to determine how much water can dissolve in the crystal structure of the common minerals (olivine, pyroxene, garnet) in the Earth's upper mantle that do not contain specific structural sites for H2O. The presence of even small amounts of water in such minerals is important because the minerals are so abundant in the Earth's mantle that the aggregate water contained in them may equal one or more times the total volume contained in the world's oceans. Additionally, the effect of dissolved water in those minerals causes drastic changes in their strength (or viscosity) and the velocity of seismic waves travelling through the mantle. We will use a variety of modern very high-pressure devices and advanced techniques for chemical analysis to complete the objectives of this project.

俯冲板块和地幔中的水：H2O EAR-0208456PI：H2O(水)对地球上的许多过程有很大的影响。这是决定火山喷发是否具有爆炸性的最重要因素。地幔矿物中少量水的存在可以削弱通常坚硬的矿物，使地幔以地质上的高速流动。在这个项目中，我们将在高温和高压下进行实验，以确定俯冲洋壳中可能存在哪些含水矿物，以及这些矿物脱水的深度。这种脱水最终导致富含水的岩浆的形成，这些岩浆经常非常爆炸性地喷发。我们还将进行实验，以确定在地球上地幔中不包含特定H2O结构位置的常见矿物(橄榄石、辉石、石榴石)的晶体结构中可以溶解多少水。这种矿物中即使只有少量的水也很重要，因为这种矿物在地幔中非常丰富，其中所含的聚合水可能相当于世界海洋总体积的一倍或几倍。此外，这些矿物中溶解的水的影响导致它们的强度(或粘度)和穿过地幔的地震波速度发生了巨大的变化。我们将使用各种现代超高压设备和先进的化学分析技术来完成这个项目的目标。