Testing the Significance of Melt Inclusions for Ocean Ridge Petrogenesis

这项研究测试了熔体包裹体成分的保真度，并为地球上火山带最丰富的洋脊岩浆的生成提供了新的见解。这项工作包括检查海底火山岩中橄榄石晶体中小熔融包裹体的组成。这项工作将确定包裹体是否表明岩浆形成的初始条件，或者它们是否被发生在地壳浅层的后期过程所改变。样本套装来自著名的大西洋中部山脊和北极的加克尔山脊。这项研究是首次对多个样品的橄榄石熔体包裹体进行全面、定量和一致的数据集。样品为叶状，成分原始。它们具有发达的局部变化，这些变化被归因于熔化柱效应。地球化学工作包括从15-20个样品中分析熔体包裹体中的主要、挥发性和微量元素。需要解决的问题包括：(1)来自不同样品的熔体包裹体的共同特征是不寻常的成分；(2)这些不寻常成分的出现与节段位置、熔岩类型或矿物学有关；(3)主要和微量元素变化与岩石成因模型的预测一致，还是用宿主晶体中的扩散更好地解释了这些变化。这项工作的更广泛影响包括让本科生参与研究和将成果纳入大学课程。它将支持一名在科学界性别比例不足的博士后研究员，并加强法国和美国实验室之间的联系。这件作品还将在哈佛自然历史博物馆(HMNH)的一个新展览中展出。地球化学数据将在PetDB中存档。一个由NSF资助的公共和互联网可访问的数据库。

This research tests the fidelity of melt inclusion compositions and provides new insights on the generation of magmas at ocean ridges, the most abundant volcanic province on Earth. The work involves examining the compositions of small melt inclusions in olivine crystals in seafloor volcanic rocks. The work will determine if the inclusions indicate initial conditions of magma formation or if they are modified by late-stage processes occurring at shallow crustal levels. The sample suite comes from the FAMOUS segment of the mid-Atlantic Ridge and the Gakkel Ridge in the Arctic. This study represents the first comprehensive, quantitative, and consistent dataset of olivine melt inclusions for multiple samples. Samples are phyric and primitive in composition. They have well-developed local variations that have been ascribed to melting column effects. Geochemical work includes the analysis of major, volatile and trace elements in melt inclusions from 15-20 samples. Questions to be addressed include: (1) are unusual compositions a common feature of melt inclusions from various samples; (2) is the occurrence of these unusual compositions related to segment position, lava type, or mineralogy; and (3) are major and trace element variations consistent with predictions from petrogenetic models or are they better explained by diffusion in the host crystal. Broader impacts of the work include engaging undergraduates in research and incorporation of results into university courses. It will support a postdoctoral fellow whose gender is under-represented in the sciences and increase bonds between a French and US laboratory. The work will also be featured in a new exhibit at the Harvard Museum of Natural History (HMNH). Geochemical data will be archived in PetDB. a public and Internet accessible database funded by NSF.