Collaborative Research/RUI: Testing Hypotheses on Pillow Lava Production During Glaciovolcanic Eruptions

合作研究/RUI：检验冰川火山喷发期间枕状熔岩产生的假设

• 批准号: 1220176
• 负责人: Meagen Pollock
• 金额: $ 12.69万
• 依托单位: College of Wooster
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220176&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Testing; Hypotheses

As recently witnessed during the 2010 Eyjafjallajokull eruption in Iceland, interactions between lava and ice can have devastating local and global implications. However, because these eruptions most frequently occur in remote, hard-to-access places, we do not fully understand many of the processes that can produce glaciovolcanic hazards from rapidly melting ice, such as floods and mudflows. In order to better understand the role of lava flow formation during eruptions within and beneath ice, we propose to study one of the products of subglacial eruptions, called 'pillow lavas'. Although pillow lavas are one of the most common types of lavas on the ocean floor, which covers about 70 percent of Earth's surface, their formation beneath ice is relatively unstudied. We are going to work in two areas with exceptionally well-exposed examples of glaciovolcanic pillow lavas in Iceland and British Columbia, Canada. Our work will help other scientists to better understand how heat is transferred from lava to water and ice during glaciovolcanic eruptions, which may lead to better methods for predicting the sizes of floods resulting from lava-ice interactions. Through our research, we will also have a better understanding of how to use pillow lavas from ancient deposits to unravel mysteries related to ice-age global climate. Finally, we hope that our data will also be useful for better understanding of the formation of the Earth's ocean floors, which may be important for future mineral and energy resources. The main goals of this research are to use pillow lavas covering a range of basaltic compositions for testing hypotheses about the formation of subglacial pillow mounds, including models for lava transport within a growing pillow-dominated volcano and the potential for sudden transitions between explosive versus effusive eruption styles. Specifically we will address the following questions:i) Is the initiation of pillow lava emplacement preceded by an explosive phase?ii) How is lava distributed along and across the ridge structure?iii) What are effusion rates during subglacial, pillow-dominated eruptions?iv) Are multiple eruptive centers active along a fissure segment during a single eruptive episode? We will pursue answers to these questions by using modern field and analytical techniques to document the three-dimensional structure, stratigraphy and geochemistry of two different pillow ridges with exceptional exposures: (1) open-pit rock quarries along a single fissure segment on the Reykjanes Peninsula in southwestern Iceland and (2) the crest of Pillow Ridge in northern British Columbia. Both locations have similar lithofacies, including a specific stratigraphic sequence of vitric tuff-breccia cut by dikes that feed pillow lava flows emplaced immediately above the tuff-breccias (TDP lithofacies association). We have established a broad-based research team, comprising US, Icelandic and Canadian scientists working in full collaboration with the PIs, to build a comprehensive database of subglacial pillow characteristics for comparison to pillow lavas produced in other environments and potentially to revise existing models for the construction of the pillow-dominated parts of subglacial volcanoes.

正如最近在冰岛举行的2010年Eyjafjallajokull爆发期间所见证的那样，熔岩和冰之间的相互作用可能会产生毁灭性的当地和全球影响。但是，由于这些喷发最常发生在遥远的，难以访问的地方，因此我们不完全了解许多可以从迅速融化的冰（例如洪水和泥泞的冰）中产生冰川的危害的过程。为了更好地了解熔岩流动在冰内和下面的作用，我们建议研究一种被称为“枕头熔岩”的冰山下喷发产物。尽管枕头熔岩是海底最常见的熔岩类型之一，覆盖了地球表面的70％，但它们在冰下的地层相对未研究。我们将在冰岛和加拿大不列颠哥伦比亚省的冰川枕头熔岩曝光的两个领域工作。我们的工作将帮助其他科学家更好地了解冰川爆发期间如何将热量从熔岩转移到水和冰，这可能会导致更好的方法来预测熔岩冰相互作用引起的洪水大小。通过我们的研究，我们还将更好地了解如何使用枕头熔岩从古老的沉积物到与冰河全球气候相关的奥秘。最后，我们希望我们的数据也有助于更好地理解地球海地的形成，这对于未来的矿产和能源可能很重要。 这项研究的主要目标是使用覆盖一系列玄武岩成分的枕头熔岩，以测试有关形成冰山下枕头丘的假设，包括在不断增长的枕头主导的火山中熔岩运输的模型，以及在爆炸性和爆发性的爆发性的突然过渡的潜力。具体而言，我们将解决以下问题：i）枕头熔岩恢复之前是爆炸性阶段吗？ii）ii）熔岩如何沿着山脊结构进行分布？我们将通过使用现代领域和分析技术来追求这些问题的答案，以记录两个不同的枕头脊的三维结构，地层和地球化学，并具有特殊的暴露：（1）沿着Reykjanes Peninsula ins Southern Iceland Iceland和（2）Crest of Fieldern的Reykjanes Peninsula沿着Reykjanes Peninsula的单个裂缝沿单个裂痕段的开放式岩石。这两个位置都有相似的岩相，包括通过堤防切割的特定地层脉冲式螺丝蛋白序列，这些堤防被喂食枕头熔岩流，该熔岩流在凝灰岩brecias上方（TDP岩相结合）上方。我们已经建立了一个基于广泛的研究团队，包括我们，冰岛和加拿大科学家与PIS完全合作，以建立一个全面的数据库，以与其他环境中生产的枕头熔岩进行比较，并有可能修订现有的现有模型，以构建枕形岩岩岩岩岩岩岩岩岩的部分。