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

合作研究：底层是什么：冰下硅质岩浆系统的调查（冰岛瓦特纳冰原）

• 批准号: 2219430
• 负责人: Tamara Carley
• 金额: $ 23.84万
• 依托单位: Lafayette College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219430&HistoricalAwards=false
• 关键词: Collaborative; Research; What; lies; beneath

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.

冰岛位于大洋中脊和地幔热柱在高纬度交汇的地方，导致了火山-冰的动态和危险的相互作用。冰岛历史上最活跃的四座火山中的两座(Grímsvötn火山和Bárçarbunga火山)位于海脊和羽流的交汇处附近，但它们在很大程度上被覆盖冰岛约10%表面积的冰帽Vatnajökull所掩盖。有迹象表明，冰川退缩会破坏现有岩浆体的稳定，甚至促使新的岩浆生成，从而导致喷发率增加。随着气候的持续变化和冰岛冰盖的不断变薄，人们越来越担心冰下火山系统受到的影响及其相关的危害。重要的是要更好地了解冰下火山系统过去和现在的行为，以便更好地为未来的火山威胁做好准备。这项研究的主要目的是探索瓦特纳约克地下岩浆的起源、演化、年龄和寿命，以便更好地了解冰岛冰川火山的潜在危险，同时了解世界上一个独特的地质部分。这项工作将加强与国内和国际科学家在该领域和分析实验室的现有合作，并促进新的合作。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，他们中的大多数来自传统上被低估的背景。在冰岛，硅质材料占裸露地壳的约10%；在中部火山，这一数字增加到约30%。与地面上的火山系统相比，瓦特纳约库尔下方的火山系统似乎缺乏硅质。这可能是由于接近脊羽交叉点的结果，或者(更有可能的)是曝光不良导致样品偏差的结果。由于与玄武岩岩浆相比，硅质岩浆喷发的可能性更大，伴随的危害也更大，因此了解硅质岩浆在Vatnajökull看不见的高产、活跃的系统中可能发挥的作用是很重要的。要调查的研究问题是：硅质材料在多大程度上与Bárçarbunga、Grímsvötn和邻近的Kverkfjöll有关？收集的硅质材料是来自活跃的岩浆系统、更老的基岩还是两者的组合？与冰岛其他地方已知的岩石记录中的硅质材料相比，这些系统的硅质材料的地球化学性质如何？硅质岩浆在这个动态的裂谷-地幔-冰柱环境中存在哪些危害？这项研究产生的数据将有助于绘制冰下硅质物质的区域分布图(既包括与活动火山系统有关的硅质物质，也包括来自较老基岩的硅质物质)。来自Nunatak和Moraine岩石(主要和微量元素；Hf、ND和Pb同位素；岩相学)及其辅助矿物(锆石：U-Th和U-Pb年龄、O和Hf同位素、痕量元素；磷灰石：微量元素、挥发物)的证据将有可能破译冰岛中部受羽流影响最严重、最活跃的火山的硅质系统的岩石成因和演化。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，认为值得支持。