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

大型火成岩省(LIP)是地球上规模最大的火山喷发的记录。这些事件的规模如此之大，以至于它们引发了环境变化，导致了灾难性的大规模灭绝和海洋缺氧事件。由嘴唇组成的岩浆是我们来自地球深处的唯一直接样本，它们以根深蒂固的上升流(称为地幔热柱)上升到地表。这些来自地球深处隔离了数十亿年的区域的样本提供了对更好地了解地球内部和外部运行的地球化学循环之间的联系至关重要的信息。例如，俯冲(地壳再循环)携带到地幔中的地壳物质对地幔长期氧化演化的影响，水等挥发物对LIP原生岩浆生成的影响，以及下地幔原始域的潜在保存仍然是理解我们地球演化的主要未知因素。这个团队建议通过研究来自哥斯达黎加西海岸(托尔图格尔)以及库拉索岛和戈尔戈纳岛的超镁铁质熔岩来阐明这些问题，这些熔岩由加勒比海嘴唇的三个不同地点组成，与加拉帕戈斯羽流的开始有关。这项研究需要回答的一个基本问题是，最近在科马提岩和嘴唇中报告的挥发性物种是深部再循环过程的结果，还是它们反映了地球深处原始的、挥发性丰富的区域。在这项拟议的研究中，研究人员提供了一个系统的方法来回答这个问题。他们将在同一样品上测定氦、臭氧和钨的同位素组成，在这些样品上进行熔融包裹体和矿物研究，以限制挥发性含量和氧化态。这些地体是本研究的理想之选，因为它们是由高度部分熔融(从而类似于其来源的成分)、记录的高结晶温度、高地幔温度以及在海底条件下快速淬火的样品形成的，潜在地将包裹体中氢的扩散损失的影响降至最低。与加拉帕戈斯羽流爆发有关的岩浆预算不稳定，将有助于量化嘴唇喷发事件期间在地球表面释放的挥发物的预算，进一步澄清嘴唇对大灭绝的影响。该项目将支持康奈尔大学的一名研究生，并为本科生提供独立研究的机会。这一项目的成果将纳入私人投资促进机构的外展和教学活动。这项拟议的研究将加强康奈尔大学、伍兹霍尔海洋研究所和马里兰大学之间的合作。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.