How anomalous is the Marion Rise asthenosphere?

马里恩隆起软流圈有多反常？

• 批准号: 2126496
• 负责人: Vincent Salters
• 金额: $ 28.73万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2126496&HistoricalAwards=false
• 关键词: How; anomalous; Marion; Rise; asthenosphere

Mid-ocean ridge volcanism is the largest element flux from the Earth’s interior to the surface and is an important contributor of carbon to the atmosphere. The magnitude of this flux is assumed to be controlled by temperature, with high temperatures causing increased melt production and magmatism, and shallow ridges. However, compositional differences in the mantle can potentially also influence melt production, but this has not been convincingly shown yet. The Marion Rise is anomalous in that melt production is low although the Rise depth is shallow. This can potentially be explained by a mantle composition that is more depleted in melt components than “normal” ridges. This research will investigate through the chemistry of the basalts and the mantle rocks from the seafloor if the Marion Rise mantle has experienced an ancient melt depletion and thus the effect of composition on ridge depth and melt production. This project is in collaboration with researchers at laboratories in Germany, Italy, and Finland and supports research training and mentoring opportunities for early career scientists.Researchers will investigate, through use of samples collected with two recent cruises to the Marion Rise as well as samples from previous cruises, to determine the nature of the Indian Ocean mantle at the eastern part of the South West Indian Ridge (SWIR). The eastern part of the SWIR includes the Marion Rise, which has anomalously thin crust for its axial depth that must be related to anomalous geochemical characteristics of the mantle beneath. This proposal is to determine the nature and extent of this anomalous mantle and thereby the cause of the Marion Rise. The Indian Ocean mid-ocean ridge basalts (MORB) differ in isotopic composition from Atlantic and Pacific MORB. The differences in Pb-isotopes (207Pb/204Pb) indicates that this difference is created early in Earth’s history. Model age determinations of the abyssal peridotites will further determine if the asthenosphere of the different ocean basins has different ages. Two recent cruises to the Marion Rise, brought back samples that address the above questions, as well as the recent availability of the samples from French expeditions further east on the SWIR allows for new insights and testing of existing hypotheses. The effort is concentrated on geochemical analyses of abyssal peridotites and associated basalts and interpreting these data in the context of geophysical constraints.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

洋中脊火山活动是从地球内部到地表最大的元素通量，是大气中碳的重要贡献者。这种通量的大小被认为是由温度控制的，高温会增加熔体的产生和岩浆活动，并造成浅脊。然而，地幔成分的差异也可能影响熔体的产生，但这一点尚未得到令人信服的证明。马里恩隆起的异常之处在于，尽管隆起深度较浅，但熔体产量却很低。这可能是由于地幔的组成比“正常”脊的熔融成分更少。这项研究将通过海底玄武岩和地幔岩石的化学成分来调查马里恩隆起的地幔是否经历了古代的熔体枯竭，从而研究成分对脊深和熔体产生的影响。该项目与德国、意大利和芬兰实验室的研究人员合作，为早期职业科学家提供研究培训和指导机会。研究人员将通过使用最近两次前往马里恩隆起的巡航收集的样本以及之前巡航收集的样本进行调查，以确定西南印度海岭（SWIR）东部印度洋地幔的性质。SWIR东部包括马里恩隆起，其轴向深度异常薄，这必然与地幔的异常地球化学特征有关。这个建议是为了确定这个异常地幔的性质和范围，从而确定马里恩隆起的原因。印度洋洋中脊玄武岩（MORB）的同位素组成与大西洋和太平洋洋中脊玄武岩不同。pb同位素（207Pb/204Pb）的差异表明，这种差异是在地球历史的早期产生的。深海橄榄岩的模式年龄测定将进一步确定不同洋盆的软流层是否具有不同的年龄。最近两次到马里恩隆起的巡航，带回了解决上述问题的样本，以及最近从法国远征队在SWIR更东的地方获得的样本，允许新的见解和现有假设的测试。工作的重点是深海橄榄岩和相关玄武岩的地球化学分析，并在地球物理限制的背景下解释这些数据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Transition from orogenic-like to anorogenic magmatism in the Southern Alps during the Early Mesozoic: Evidence from elemental and Nd-Sr-Hf-Pb isotope geochemistry of alkali-rich dykes from the Finero Phlogopite Peridotite, Ivrea–Verbano Zone

• DOI: 10.1016/j.gr.2023.12.011
• 发表时间: 2023-12
• 期刊: Gondwana Research
• 影响因子: 6.1
• 作者: Abimbola C. Ogunyele;M. Bonazzi;T. Giovanardi;M. Mazzucchelli;V. Salters;A. Decarlis;Alessio Sanfilippo;Alberto Zanetti

Preserved Nd-Hf-Os isotope variability in replacive channels from the Lanzo ophiolite: Traces of incomplete melt aggregation in the shallow mantle

• DOI: 10.1016/j.chemgeo.2023.121779
• 发表时间: 2023-10
• 期刊: Chemical Geology
• 影响因子: 3.9
• 作者: A. Sanfilippo;C.Z. Liu;V. Salters;A. Mosconi;A. Zanetti;R. Tribuzio

Shallow recycling of lower continental crust: The Mahoney Seamount at the Southwest Indian Ridge

下大陆地壳的浅层再循环：西南印度洋脊的马奥尼海山

• DOI: 10.1016/j.epsl.2022.117968
• 发表时间: 2023
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Woelki, Dominic;Salters, Vincent;Beier, Christoph;Dick, Henry;Koepke, Juergen;Romer, Rene
• 通讯作者: Romer, Rene