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

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。MID-洋脊是新地壳生成的主要地点。由于地壳的形成影响了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作用的地球化学线索，对于我们了解地球是如何运行的至关重要。这项研究使用最先进的离子探针分析橄榄石赋存的熔体包裹体，以检查导致大洋中脊喷发的熔岩化学的岩浆过程。它的重点是确定挥发性相的浓度，如H2O和CO2，已知的是控制地幔融化和影响喷发过程的挥发性相。来自西南印度洋海脊和其他缓慢和超低扩散中心的样本将被分析。这些数据来自以较冷的热制度、较低的平均融化程度和极其集中的火山活动为特征的环境，将与来自更快扩张山脊的数据进行比较。项目成果包括：(1)确定大洋中脊轴线下一定深度范围内H2O与融化程度之间的关系，(2)确定沿大洋脊线的熔体化学变化，以及(3)量化来自超慢的大洋中脊扩散环境的挥发性通量。此外，这项工作有助于我们更好地评估橄榄石中的熔融包裹体在多大程度上记录了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在科学和本科培训中性别比例不足的早期职业科学家。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.