Collaborative Research: What lies beneath: An investigation of subglacial silicic magma systems (Vatnajokull, Iceland)

冰岛位于大洋中脊和地幔柱在高纬度相交的地方，导致了动态和危险的火山-冰相互作用。冰岛历史上四座最活跃的火山中的两座（格里姆斯火山和巴尔纳本加火山）位于山脊和羽流的交汇处附近，但它们在很大程度上被瓦特纳冰川所掩盖，这是一个覆盖冰岛表面积约10%的冰帽。有迹象表明，冰川退缩可能会导致现有岩浆体不稳定，甚至促使新的岩浆产生，从而增加喷发率。随着气候继续变化，冰岛的冰盖继续变薄，人们越来越担心冰下火山系统受到的影响及其相关危害。更好地了解冰下火山系统的过去和现在的行为，以更好地为未来的火山威胁做好准备是很重要的。这项研究的主要目的是探索瓦特纳冰川下岩浆的起源、演化、年龄和寿命，以便更好地了解冰岛的冰川-火山危险潜力，同时了解世界上地质独特的一部分。这项工作将加强现有的，并促进新的，与国内和国际科学家在该领域和分析实验室的合作。它还将为社区参与和公共教育创造机会，并为6名以上的本科生提供严格的研究经验，其中大多数人来自传统上代表性不足的背景。在冰岛，火山物质占暴露地壳的约10%;在中央火山，这一数量增加到约30%。瓦特纳冰盖下的火山系统似乎相对于其陆上对应物而言缺乏可吸收物质。这可能是由于靠近洋脊-羽流交叉点，或者（更可能）是由于暴露不良导致样品偏差。由于火山岩浆有可能比玄武岩浆爆发得更猛烈，相关的危害也更大，因此了解它们在被瓦特纳火山遮住的多产、活跃系统中可能发挥的作用是很重要的。研究的问题是：在何种程度上是相关的Bárarbunga，格里姆火山，和邻近的Kverkfjöll的物质？收集到的岩石材料是否来自活跃的岩浆系统、更古老的基岩或两者的结合？这些系统的岩石物质的地球化学特征与冰岛其他地方已知的岩石记录相比如何？在这种动态的裂谷-地幔柱-冰环境中，岩浆存在什么样的危险？这项研究产生的数据将有助于绘制冰下碎屑物质（与活火山系统有关的物质和来自较老基岩的物质）的区域分布图。冰原岛峰和冰碛岩的证据（主微量元素; Hf、Nd、Pb同位素;岩相学）及其副矿物（锆石：U-Th和U-Pb年龄，O和Hf同位素，微量元素;磷灰石：微量元素，挥发物）将有可能破译冰岛最受羽流影响，最活跃，该奖项反映了NSF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。

Iceland is positioned where a mid-ocean ridge and a mantle plume intersect at high latitude, resulting in dynamic and dangerous volcano-ice interactions. Two of Iceland’s four most historically active volcanoes (Grímsvötn and Bárðarbunga) occur near the intersection of the ridge and plume, but they are largely obscured from view by Vatnajökull, an ice cap that covers ~10% of Iceland’s surface area. There are indications that glacial retreat can lead to increased eruption rates by destabilizing existing magma bodies and even prompting new magma generation. As climate continues to change and Iceland’s ice caps continue to thin, there is increasing concern about the impacts on subglacial volcanic systems and their associated hazards. It is important to better understand past and present behavior of subglacial volcanic systems to better prepare for future volcanic threats. The primary objective of this study is to explore the origin, evolution, age, and longevity of magmas under Vatnajökull in order to better understand Iceland’s glacio-volcanic hazard potential, while simultaneously learning about a geologically unique part of the world. This work will strengthen existing, and facilitate new, collaborations with domestic and international scientists in the field and in analytical labs. It will also create opportunity for community engagement and public education, and provide rigorous research experiences for 6+ undergraduate students, a majority of whom are from traditionally under-represented backgrounds.In Iceland, silicic material accounts for ~10% of the exposed crust; at central volcanoes, this amount increases to ~30%. Volcanic systems beneath Vatnajökull appear to have a paucity of silicic material relative to their subaerial counterparts. This may be a consequence of the proximity to the ridge-plume intersection, or (more likely) a consequence of poor exposure leading to sample bias. Since silicic magmas have the potential to erupt more explosively and with greater associated hazards than basaltic magmas, it is important to understand the role they may play at the productive, active, systems obscured from view by Vatnajökull. The research questions to be investigated are: To what extent are silicic materials associated with Bárðarbunga, Grímsvötn, and neighboring Kverkfjöll? Are collected silicic materials from active magmatic systems, older bedrock, or a combination? How do the geochemical characteristics of these systems’ silicic materials compare to those in the known rock record elsewhere in Iceland? What hazards do silicic magmas present in this dynamic rift-mantle plume-ice environment? Data generated in this study will facilitate mapping the regional distribution of subglacial silicic materials (both those associated with active volcanic systems and those from older bedrock). Evidence from nunatak and moraine rocks (major and trace elements; Hf, Nd, and Pb isotopes; petrography) and their accessory minerals (zircon: U-Th and U-Pb dates, O and Hf isotopes, trace elements; apatite: trace elements, volatiles) will make it possible to decipher the petrogenetic origins and evolution of silicic systems at Iceland’s most plume-affected, and most active, central volcanoes.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.