Physical and Chemical Processes in the Shallow Plumbing Systems of Monogenetic Volcanoes

这项研究解决了关于单一成因火山内化学多样性的起源以及组成其浅层管道系统的岩脉和岩床中岩浆的物理行为的单独但相关的问题。这项研究的一个结果将是检验这样一个假设，即含晶体岩浆的流动分化可以在这些火山的整个熔岩流和火山灰之间产生更大规模的成分变化方面发挥重要作用。这项研究的重点是辛克巴特火山，这是爱达荷州斯内克河平原西部的一座成分多样的玄武岩屏蔽凝灰岩锥杂岩。这一遗址提供了一个非同寻常的研究机会，因为火山已经被蛇河解剖，暴露了峡谷壁上的熔岩流、火山灰和放射状堤坝的完整序列。岩浆在岩脉和岩层中的流动方向将通过测定钻井岩心的磁化率各向异性(AMS)来估计。对流动方向的独立估计将通过统计分析薄片中的晶体取向来做出。岩脉内部和之间的化学变化将与斑晶模式和运动方向进行比较，以评估水流分异的影响。这项研究将有助于更好地了解短暂的玄武岩火山的物理和化学过程，这些火山是地球上最常见的非海洋火山类型。通过专注于火山内部运行的物理机制，该项目建立在最近对芒特山浅层管道系统的研究基础上。意大利的埃特纳和夏威夷的基拉韦厄火山。这项研究的更广泛的影响包括对本科生和研究生的研究培训，以及从这项研究中获得的知识将有助于评估与玄武岩火山意外爆发相关的危险的信息的可能性。该项目得到了EPSCoR(EHR)和岩石学和地球化学(EAR)计划的支持。

This research addresses separate but related questions about the origin of chemical diversity within monogenetic volcanoes and the physical behaviors of magmas in the dikes and sills that comprise their shallow plumbing systems. One outcome of the research will be to test the hypothesis that flow differentiation of crystal bearing magmas can play an important role in producing larger scale compositional variations among the entire suite of lava flows and tephra at these volcanoes. The study focuses on the Sinker Butte volcano, a compositionally diverse basaltic shield-tuff cone complex in the western Snake River Plain of Idaho. This site affords an extraordinary research opportunity because the volcano has been dissected by the Snake River, exposing a complete sequence of lava flows, tephra, and radial dikes in the canyon walls. Flow directions of magma in the dikes and sheets will be estimated by determining anisotropy of magnetic susceptibility (AMS) in drilled cores. An independent estimate of flow directions will be made by statistically analyzing crystal orientations in thin sections. Chemical variations within and among dikes will be compared with phenocryst modes and movement directions to assess the effects of flow differentiation. This study will contribute to a better understanding of the physical and chemical processes operating at short-lived, basaltic volcanoes, which are the most common type of non-marine volcano on our planet. By focusing on the physical mechanisms that operate inside volcanoes, the project builds on recent studies of the shallow plumbing systems at Mt. Etna in Italy and Kilauea volcano in Hawaii. Broader impacts of the study include research training for students at the undergraduate and graduate level, and the possibility that knowledge gained from this study will contribute information useful for assessing hazards associated with unexpected explosive eruptions at basaltic volcanoes.This project is being supported by both the EPSCoR (EHR) and the Petrology and Geochemistry (EAR) programs.