25 Million Years of Mantle Upwelling below the Mid Atlantic Ridge: The Vema Lithopsheric Section Revisited

博纳蒂(0551288)的学术价值：这项研究是一个项目的继续，该项目研究了沿维马岩石圈部分暴露出上地幔和海底地壳单元的大洋岩石圈隆起的狭长地带。这一领域提供了一个机会来监测海底岩石圈的形成过程在过去2500万年中发生了怎样的变化。该项目将多波束、重、磁和地震反射地球物理数据与暴露的地幔超镁铁基单元和地壳玄武岩单元的近距离地球化学样品的地球化学和同位素分析结合在一起。橄榄岩、辉长岩和玄武岩(包括新鲜玻璃)的样品是在2005年4月至5月的野外季节采集的，使最初的研究增加了32个地点，并将样本系列的时间覆盖范围延长了1000万年。地球化学工作包括地幔平衡辉石和尖晶石的主元素和微量元素分析。这些数据将被用来改进地幔热物性、成分和熔融过程的模式。将使用玄武岩玻璃的主要元素和微量元素分析来获得对地幔熔融程度的独立估计。橄榄岩和玄武岩玻璃中辉石的锶-钕-铅同位素组成将被用来确定地幔和地壳玄武岩之间的成因联系。结果将检验这样一种观点，即上地幔橄榄岩的短尺度同位素不均匀在来自上地幔大片区域的熔体中均一化。这项研究结合了地球化学和地球物理数据，将可以对岩石圈的形成进行3D建模。更广泛的影响：该项目将资助纽约州的研究人员，其中一人是早期职业生涯的女性科学家。本科生将参与这项研究，纽约城市大学城市皇后学院校区的教职员工和学生也将参与这项研究，那里的少数民族入学率很高，在科学界的代表性不足。分析数据将被存档，并通过Lamont-Doherty地球天文台的PetDb岩石学数据库向公众提供。

ABSTRACT Bonatti (0551288)Intellectual Merit: This research is the continuation of a project that studies an uplifted sliver of oceanic lithosphere that exposes upper mantle and seafloor crustal units along the Vema Lithospheric Section. This field area provides an opportunity to monitor how processes of seafloor lithospheric generation have changed over the last 25 million years. The project combines multibeam, gravity, magnetics and seismic reflection geophysical data with geochemical and isotopic analyses of closely spaced geochemical samples of the exposed mantle ultramafic basal units and the crustal basaltic units. Samples of peridotites, gabbros, and basalts (including fresh glass) were collected during the April-May 2005 field season augmenting the original study by 32 additional sites and extending the time coverage of the sample suite by 10 million years. Geochemical work includes major and trace element analyses of mantle equilibrated pyroxenes and spinels. These data will be used to refine patterns of mantle thermal properties, composition, and melting processes. Major and trace element analyses of basaltic glasses will be used to obtain independent estimates of the extent of mantle melting. Sr-Nd-Pb isotope compositions of pyroxenes from peridotites and basaltic glasses will be used to determine genetic links between the mantle and crustal basalts. Results will test the idea that short-scale isotopic heterogeneities of upper mantle peridotites are homogenized in the melt that derives from a broad region of the upper mantle. Combined geochemical and geophysical data from the study will permit 3D modeling of lithosphere formation. Broader impacts: This project will fund researchers from New York State, one of whom is a female, early career scientist. Undergraduates will be involved in the research as will faculty and students at the urban Queens College campus of the City University of New York which has a high enrollment of minorities under-represented in the sciences. Analytical data will be archived and made available to the public through the PetDb petrologic database at Lamont-Doherty Earth Observatory.