Collaborative Research: The Onset of the Galapagos Plume as a Window Into the Deep Earth

大火成岩省（LIPs）是地球上最大规模火山爆发的记录。这些事件是如此之大，它们引发了环境变化，导致灾难性的大规模灭绝和海洋缺氧事件。组成LIPs的岩浆是我们唯一来自地球深部的直接样本，它们在被称为地幔柱的根深蒂固的隆起中上升到地表。这些来自地球深处数十亿年来孤立的区域的样本提供了对更好地了解地球内部和外部地球化学循环之间联系至关重要的信息。例如，通过俯冲（地壳再循环）进入地幔的地壳物质对地幔长期氧化演化的影响，挥发物（如水）对LIP原始岩浆生成的影响，以及下地幔中原始域的潜在保存仍然是我们星球演化的主要未知因素。这个研究小组建议通过研究来自哥斯达黎加西海岸的超镁铁质熔岩来阐明这些问题（托尔图加尔）以及库拉考和戈尔戈纳岛，包括三个不同的地方，加勒比LIP的残余，与加拉帕戈斯羽的开始有关。在这项研究中要回答的一个基本问题是，最近报道的科马提岩和LIPs中的挥发性物质是否是深度再循环的结果或者它们是否反映了地球深处原始的、挥发性丰富的区域。在这项研究中，研究人员提供了一种系统的方法来回答这个问题。他们将确定氦，锇和钨的同位素组成，在同一样品上，他们将进行熔体包裹体和矿物研究，以限制挥发性成分和氧化态。这些岩石是这项研究的理想选择，因为它们是由高度的部分熔融形成的（从而类似于其来源的成分），记录了高结晶温度，高地幔电位温度，并且样品在海底条件下快速淬火，可能会最大限度地减少夹杂物中氢的扩散损失的影响。与加拉帕戈斯羽流的爆发有关的岩浆的挥发性预算将有助于量化LIP喷发事件期间在地球表面释放的挥发物的预算，进一步澄清LIP对大规模喷发的影响。该项目将支持康奈尔大学的研究生，并为本科生提供独立研究的机会。该项目的成果将纳入方案研究所的外联和教学活动。这项研究将加强康奈尔大学、伍兹霍尔海洋研究所和马里兰州大学之间的合作。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Large igneous provinces (LIPs) are the record of the most voluminous volcanic eruptions on Earth. These events were so large that they triggered environmental change leading to catastrophic mass extinctions and oceanic anoxic events. The magmas comprising LIPs are our only direct samples from the deep Earth, having ascended to the surface in deeply rooted upwellings known as mantle plumes. These samples from regions that have been isolated deep within the Earth for billions of years provide information that is crucial for gaining a better understanding the links between geochemical cycles operating on the interior and exterior of our planet. For example, the effect of crustal materials carried into the mantle by subduction (crustal recycling) on the long-term oxidation evolution of the mantle, the effect of volatiles such as water on the generation of LIP primary magmas, and the potential preservation of primordial domains in the lower mantle remain major unknowns in the understanding of the evolution of our planet. This team proposes to shed new light on these questions by studying ultramafic lavas from the west coast of Costa Rica (Tortugal) as well as the islands of Curacao and Gorgona, comprising three distinct localities remnants of Caribbean LIP that are related to the onset of the Galapagos Plume ~89 Ma.A fundamental question to be answered in this study is whether volatile species recently reported in komatiites and LIPs are the result of deep recycling processes or if they reflect primordial, volatile-rich domains within the deep Earth. In the proposed study, researchers provide a systematic approach to answering this question. They will determine the isotopic compositions of helium, osmium, and tungsten on the same samples on which they will perform melt inclusion and mineral studies to constrain volatile contents and oxidation state. These terranes are ideal for this study as they formed by high-degrees of partial melting (thereby resembling the composition of their source), record high crystallization temperatures, high mantle potential temperatures, and the samples rapidly quenched at submarine conditions potentially minimizing the effects of diffusive loss of hydrogen from the inclusions. The volatile budgets of magmas related to the onset of the Galapagos Plume will help quantify the budget of volatiles released at Earth's surface during LIP eruption events, further clarifying the effects of LIPs on mass extinctions. This project will support a graduate student at Cornell, as well as provide independent research opportunities to undergraduate students. Results from this project will be incorporated in outreach and teaching activities of the PIs. This proposed research will enhance collaborations among Cornell, Woods Hole Oceanographic Institution, and the University of Maryland.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.