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

大西洋中脊以下地幔上涌 2500 万年：重温维玛岩石层剖面

• 批准号: 0551288
• 负责人: Enrico Bonatti
• 金额: $ 34.13万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0551288&HistoricalAwards=false
• 关键词: 25; Million; Years; Mantle; Upwelling

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.

摘要 Bonatti (0551288) 学术价值：这项研究是一个项目的延续，该项目研究了一条隆起的海洋岩石圈，暴露了沿维马岩石圈剖面的上地幔和海底地壳单元。 该区域提供了监测过去 2500 万年海底岩石圈生成过程如何变化的机会。 该项目将多波束、重力、磁力和地震反射地球物理数据与暴露的地幔超镁铁质基底单元和地壳玄武岩单元的紧密间隔地球化学样本的地球化学和同位素分析结合起来。 在 2005 年 4 月至 5 月的野外季节期间收集了橄榄岩、辉长岩和玄武岩（包括新鲜玻璃）样本，通过增加 32 个地点扩大了最初的研究，并将样本组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量元素和微量元素分析。 这些数据将用于完善地幔热特性、成分和熔化过程的模式。 玄武岩玻璃的主量和微量元素分析将用于获得对地幔熔化程度的独立估计。 来自橄榄岩和玄武岩玻璃的辉石的 Sr-Nd-Pb 同位素组成将用于确定地幔和地壳玄武岩之间的遗传联系。 结果将验证上地幔橄榄岩的短尺度同位素异质性在源自上地幔广大区域的熔体中均质化的观点。该研究的综合地球化学和地球物理数据将允许对岩石圈形成进行 3D 建模。更广泛的影响：该项目将资助来自纽约州的研究人员，其中一名是女性、早期职业科学家。本科生以及纽约市立大学皇后学院城市校区的教职员工和学生都将参与这项研究，该校区的少数族裔入学率很高，而在科学领域代表性不足。 分析数据将被存档并通过拉蒙特-多尔蒂地球观测站的 PetDb 岩石学数据库向公众开放。