Understanding the Diverse Isotopic Record of Volcanism in Kamchatka

本项目是对俄罗斯堪察加半岛最活跃的俯冲相关火山弧之一的火山岩氧和放射性同位素记录进行详细调查。研究将集中在更新世至最近三个最大的多火山口中心发生的冰川作用和火山作用的相互作用所引起的地球化学效应。这项研究将为丰富的14c地层年代学记录增加一个补充的40Ar/39Ar地质年代学数据集，这将使堪察加半岛整个更新世的火山地层校准成为可能。这些信息将与国际合作者的放射性成因同位素测量相结合，以确定来源，并限制18O同位素耗尽的起源和寿命。堪察加半岛非常适合这项研究，因为它拥有地球上最大的亚北极大气地热和间歇泉系统。这些氧同位素耗尽是火山口衍生的硅质岩石的特征，可能是由于非常浅的水热蚀变地壳的同化/融化。该项目将测试从初步证据中得出的模型，该模型将这些氧同位素消耗与火山口崩塌和冰川消融联系起来。这里提出的研究将测试冰川对火山作用的反馈假设，这是一种很少被研究的现象。该研究结果将对亚北极地区气候变化、火山灾害和环境稳定等紧迫的社会问题具有重要的应用价值。堪察加主要破火山口喷发（100 km3）的火成岩定年将更好地约束人类在堪察加定居和通过白令海陆桥迁移到北美的背景下的晚更新世全球火山活动记录，并确定主要破火山口形成中心，与格陵兰冰芯记录以及北太平洋和白令陆桥的海洋火山灰序列进行对比。该项目将为新教员的专业发展提供基础，有助于加强俄勒冈大学新建立的稳定同位素实验室的基础设施。该项目还将促进国际合作，并允许将确定的研究生培养为研究科学家，并为本科生提供获得重要研究经验的机会。

This project is to undertake a detailed investigation of the oxygen and radiogenic isotope record of volcanic rocks in one of the most active subduction-related volcanic arcs, the Kamchatka Peninsula, Russia. The study will focus on the geochemical effects caused by the interplay of glaciation and volcanism occurring between the Pleistocene to recent on the three largest multi-caldera centers. This study will add a complementary 40Ar/39Ar geochronologic dataset to the abundant 14 C tephrochronological record that will allow unprecedented calibration of the volcanic stratigraphy of Kamchatka throughout the Pleistocene. This information will be combined with radiogenic isotope measurements by the international collaborators to fingerprint sources and constrain the origin and longevity of 18O isotopic depletions. Kamchatka is ideally suited for this investigation because it hosts the largest subarctic meteoric-geothermal and geyser system on Earth. These oxygen isotope depletions characterize caldera-derived silicic rocks and may be due to assimilation/melting of the very shallow hydrothermally-altered crust. The project will test the model derived from preliminary evidence that links these oxygen isotope depletions to caldera collapse and deglaciation The study proposed here will test the hypothesis that there is a glacial feedback on volcanism, a phenomenon that has rarely been investigated. The results of this research will have important applications to several urgent social issues including climate change, volcanic hazards, and environmental stability in the subarctic. Dating of ignimbrites of major caldera-forming eruptions (100 km3) in Kamchatka will better constrain the record of global volcanism during the late Pleistocene in the context of human settlement of Kamchatka and migration to N. America through the Bering land bridge, and identify major caldera-forming centers for correlation with the ice core record in Greenland and with marine ash sequences in the N. Pacific and Beringia. This project will provide a basis for professional development of a new faculty member, aid in the enhancement of the infrastructure of the newly established stable isotope laboratory at the University of Oregon. The project will also foster international collaborations and allow the training of an identified graduate student as a research scientist as well as provide an opportunity for an undergraduate student to gain significant research experience.