Building volcanic ash records to date and correlate paleoenvironmental archives and improve volcanic histories

火山灰(或称火山灰)对于研究重建过去的环境和火山史很重要。每一个Tephra都可以通过地球化学性质的“指纹”来确定年代，从而将它们在空间和时间中的地质记录联系在一起。北美西北部包括阿留申火山，这是世界上第三活跃的火山弧，以及不太活跃但更危险的喀斯喀特火山。令人惊讶的是，该地区的特弗拉记录并不发达，尤其是最近的18,000年。我们经常遗漏关键数据，如地球化学、地层学、年龄和火山源。我的研究计划的首要目标是为北美西北部建立一个全面的火山记录，为古环境和火山学研究提供信息。我的建议通过以下两个主题探讨这一长期目标： 建立Tephra框架，以确定、关联和解释过去气候的记录： 要了解今天地球气候变化的方式和原因，我们需要了解过去气候的自然变异性。这与加拿大特别相关，因为北部地区经历了放大的气候变化。重建过去气候的关键数据可以在阿拉斯加西南部的年度层状(变色)湖泊沉积、加拿大冰芯档案馆保存的加拿大北极冰芯和阿拉斯加湾海洋沉积物芯中找到。对这些沉积物进行测年和关联以帮助解释它们的意义是必不可少的，但很少有人研究过。该提案提出了几个项目，这些项目将研究这些矿床中的特弗拉，将它们彼此结合起来，同时为未来的古环境研究建立特弗拉框架的目标。 通过Tephra提高我们对火山过程和历史的理解： Tephra是分析过去火山事件的基本组成部分，例如过去火山喷发的规模和频率，驱动它们的潜在过程，以及它们对现代社会的危害。用来研究这些问题的数据通常是从火山附近或火山上的沉积物中收集的，但反复发生的喷发和侵蚀往往会破坏过去喷发的近距离证据。远端(距源头10公里)的火山灰帮助填补了这些空白，形成了更完整的火山史。该提案的这一方面从根本上与前面的主题交织在一起，但在这里，我将重点放在这些沉积物中的火山灰如何帮助我们了解喷发历史和动力学。对于这项具体建议，我的目标是解决一些阻碍我们以这种方式使用非洲菊的能力的根本问题。这包括改进地球化学技术，以追踪特弗拉的火山源或区域，并研究历史喷发，如1980年圣海伦斯火山喷发，以改进我们通过其地质记录对史前喷发的解释。

Volcanic ashes (or tephra) are important for research reconstructing past environments and volcanic histories. Each tephra can be geochemically “fingerprinted” and dated, linking together the geologic records they were deposited in through space and time. Northwestern North America includes the Aleutian arc, the third most active volcanic arc in the world, and the less active, but more hazardous, Cascade arc. Surprisingly, tephra records for this region are underdeveloped, particularly for the most recent ~18,000 years. We are often missing critical data such as geochemistry, stratigraphy, age, and volcanic source. The overarching goal for my research program is to build a comprehensive volcanic record for NW North America that will inform both paleoenvironmental and volcanological studies. My proposal explores this long-term objective through these two themes: Building tephra frameworks to date, correlate and interpret records of past climate: Understanding how and why Earth's climate is changing today requires us to understand the natural variability of climate in the past. This is particularly relevant to Canada as northern regions experience amplified climate change. Key data for reconstructing past climate can be found in annually laminated (varved) lake deposits from SW Alaska, Canadian arctic ice cores held in the Canadian Ice Core Archive, and Gulf of Alaska marine sediment cores. Tephra are essential for dating and correlating these deposits to help interpret their significance, but few have been studied. This proposal presents several projects that will study tephra within these deposits, integrating them with one another, while building towards the objective of developing a tephra framework for future paleoenvironmental studies. Improving our understanding of volcanic processes and histories through tephra: Tephra are a fundamental component in parsing past volcanic events, such as the magnitude and frequency of past eruptions, the underlying processes driving them, and their hazards to modern society. Data used to examine these questions are often gathered from deposits close to or on the volcanoes, but reoccurring eruptions and erosion often destroys this proximal evidence of past eruptions. Distal (>10 km from source) tephra help fill these gaps and develop more complete volcanic histories. This aspect of the proposal is fundamentally intertwined with the previous theme, but here I focus on how tephra in these deposits can help us understand eruption histories and dynamics. For this specific proposal I aim to address some fundamental problems that hinder our ability to use tephra in this manner. This includes refining geochemical techniques for tracing tephra to their volcanic source or region, and examining historical eruptions, such as the 1980 eruption of Mount St. Helens, to improve our interpretation of pre-historic eruptions through their geologic records.