Causes and Consequences of Holocene Mafic Explosive Volcanism in Central OR

俄勒冈州中部在过去的10,000年里一直是纽贝里火山和分布在整个俄勒冈州中部小瀑布的喷口的众多火山爆发的地点。这些喷发大多产生了玄武岩熔岩流和火山锥，据怀疑，许多喷发还产生了大量的喷发柱，可能将少量火山灰分布在大片地区。由于俄勒冈州中部最大城市弯曲的人口自2000年以来增加了50%（目前人口约为75，000人），并且弯曲位于喀斯喀特山脉的东部（顺风），并建造在纽贝里火山（指定为a？非常高的威胁？火山），重要的是要了解未来潜在的危害范围所造成的火山灰产生的喷发，可能会影响空中交通，娱乐，和农业。为了确保这项工作可供当地居民使用，他们将与美国地质调查局和美国林务局的科学家和口译员协调，翻译调查结果，并改善与俄勒冈州中部火山活动各方面有关的外联工作。 为了改善俄勒冈州中部的火山灾害评估，建议研究几次不同喷发产生的沉积物，其中许多发生在过去的2000年。 具体来说，他们将绘制和采样来自（1）北姐妹成层火山（Yapoah，Four-in-One和Collier Cone）北部的年轻火山渣锥;（2）年轻的盾状火山Belknap Crater;和（3）纽贝里火山最近的玄武岩喷发，大约7000年前沿着其西北裂谷区喷发。 目标之一是确定火山灰和火山渣沉积物的厚度和分布，因为这些沉积物构成该区域今后火山爆发的主要危险，并确定岩浆的挥发性（水和二氧化碳）含量，以确定上升岩浆的挥发性含量在多大程度上控制火山爆发的方式（爆炸或喷出，即以火山灰沉积物或熔岩流为主）。特别是，人们相信这项工作将提供洞察的条件，导致玄武岩浆爆发。 另一个目标将是使用亚高山湖泊核心研究更远的火山灰沉积物;这项工作将与地理系的同事合作，因为这些核心中火山灰沉积物的识别将使他们能够评估过去2000年来植物对火山爆发的反应。总的来说，拟议的工作是独特的，因为他们希望结合联合收割机的岩石学方法（通过研究岩浆挥发物和火山灰结构）和物理火山学（通过研究火山灰沉积物的性质），以开发驱动单成因或小型多成因镁铁质喷发的岩浆系统的全面图片。

Central Oregon has been the site of numerous volcanic eruptions in the past 10,000 years from both Newberry Volcano and vents distributed throughout the central Oregon Cascades. Most of these eruptions have produced basaltic lava flows and cinder cones and it is suspected that many of the eruptions also created substantial eruption columns that could have distributed small amounts of volcanic ash over large regions. As the population of the largest city in central Oregon, Bend, has increased by 50% since 2000 (the population is currently ~ 75,000) and as Bend lies east (downwind) of the Cascades and is constructed on distal lava flows and scoria cones from Newberry Volcano (designated a ?very high threat? volcano by the USGS), it is important to understand the scope of potential future hazards posed by ash-producing eruptions that could affect air traffic, recreation, and agriculture. To insure that this work is available to local populations, they will coordinate with both U.S. Geological Survey and U.S. Forest Service scientists and interpreters to translate findings and improve outreach efforts related to all aspects of volcanism in central Oregon. To improve volcanic hazard assessment in central Oregon, it is proposed to study deposits produced by several different eruptions, many of which have occurred over the past 2000 years. Specifically, they will map and sample deposits from (1) young scoria cones north of North Sister stratovolcano (Yapoah, Four-in-One, and Collier Cone); (2) the young shield volcano Belknap Crater; and (3) the most recent basaltic eruptions of Newberry Volcano, erupted along its northwest rift zone about 7000 years ago. One of the goals is to determine both the thickness and distribution of ash and scoria deposits, as these pose the primary hazard from future eruptions in the region, and the volatile (water and carbon dioxide) content of the magma, to determine the extent to which the volatile content of the rising magma controls the eruptive style (explosive or effusive, that is, dominated by ash deposits or lava flows). In particular, it is believed that this work will provide insights into conditions that cause basaltic magma to erupt explosively. Another goal will be to study more distal ash deposits using sub-alpine lake cores; this work will be collaborative with colleagues from the Geography department, as identification of ash deposits in these cores will allow them to assess the vegetative response to eruptions over the past 2000 years. Taken as a whole, the proposed work is unique in its approach in that they hope to combine methods from petrology (by studying magmatic volatiles and tephra textures) and physical volcanology (by studying the nature of the tephra deposits) to develop of comprehensive picture of the magmatic systems that drive monogenetic or small polygenetic mafic eruptions.