Collaborative Research: Using Melt Inclusions to Test Models for Wet Melting and Melt Extraction Beneath Mid-Ocean Ridges

该奖项由2009年《美国复苏和再投资法》（公法111-5）资助。 由于地壳的形成会影响生成区域的地壳和地幔结构，因此能够读取地表喷发熔岩中深层岩浆过程的地球化学线索对于我们了解地球如何运作至关重要。 这项研究使用最先进的离子探针分析橄榄石托管熔融包裹体，以检查岩浆过程，导致在洋中脊喷发的熔岩的化学。它的重点是确定挥发性相的浓度，如H2O和CO2，这是已知的控制地幔熔融和冲击喷发过程。 来自西南印度洋脊和其他慢速和超慢速扩张中心的样本将被分析。 来自温度较低、平均融化程度较低和火山活动极为集中的环境的数据将与来自扩张较快的海脊的数据进行比较。 项目成果包括：（1）确定在大洋中脊轴以下一定深度范围内H2O与熔融程度之间的关系，（2）确定熔融化学沿着脊的变化，（3）量化大洋中脊超缓慢扩张环境中的挥发性通量。 此外，这项工作有助于我们更好地评估在何种程度上橄榄石托管熔融包裹体记录在其他地质环境中的熔融过程。 这项工作的更广泛影响包括支持一名早期职业科学家，其性别在科学和本科生培训中代表性不足。 结果也将在NSF资助的PetDB数据库上公开。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Mid-ocean ridges are the primary location of new crust generation. Because crustal creation impacts the structure of the crust and mantle in the region of generation, being able to read the geochemical clues of deep seated magmatic processes in surface-erupted lavas is critical to our knowledge of how the Earth works. This research uses state-of-the-art ion probe analyses of olivine hosted melt inclusions to examine magmatic processes that result in the chemistry of lavas erupted at mid-ocean ridges. It focuses on determining the concentrations of volatile phases, such as H2O and CO2, that are known to control mantle melting and impact eruption processes. Samples from the Southwest Indian Ridge and other slow and ultraslow spreading centers will be analyzed. The data which come from environments characterized by cooler thermal regimes; lower average degrees of melting; and extremely focused volcanism, will be compared with data from faster spreading ridges. Project outcomes include: (1) characterizing the relationship between H2O and degree of melting over a range of depths beneath mid-ocean ridge axes, (2) determining changes in melt chemistry along the ridges, and (3) quantifying volatile fluxes from ultra-slow mid-ocean ridge spreading environments. In addition the work helps us to better evaluate the extent to which olivine hosted melt inclusions record melting processes in other geologic settings. Broader impacts of the work include support for an early career scientist whose gender is under-represented in the sciences and undergraduate training. Results will also be made publicly available on the NSF-funded PetDB database.