Whodunit? Determining the source and climatic forcing of unidentified volcanic eruptions from ice core archives.

大型火山事件的影响和频率对我们的社会很重要，对全球气候、政府以及航空和农业等行业都有影响。如果火山羽流到达平流层并在全球循环，那么大气中火山硫酸盐气溶胶排放的冷却作用就会延长（Robock 2000）。因此，对过去火山活动进行准确、高分辨率的记录，对于了解对我们社会有重大影响的大型火山事件的频率和气候影响非常重要。我们可以从冰芯记录中更多地了解大型火山事件的规模和位置，这可以保存本地和远端喷发的硫酸盐和灰层（例如：Sigl et al. 2015）。因此，这种连续的、高分辨率的冰记录对于了解过去的火山与气候的联系是非常宝贵的。该项目旨在利用火山硫酸盐沉积物的硫同位素分析和冰芯记录中tephra碎片的地球化学特征来确定最近地质历史（<20万年）大喷发的羽流高度、源火山和气候强迫。多种硫同位素分析将使用柱化学和多收集器电感耦合等离子体质谱（MC-ICP-MS）进行。同位素特征将有助于通过存在（或不存在）质量无关分力来确定平流层或对流层的羽流高度（Baroni等人，2007年，2008年），并通过比较同位素数据和冰芯喷发记录中的SO4浓度曲线来确定源火山的纬度（Burke等人，2019年）。来自大型未知火山喷发的火山泥将使用电子探针显微分析进行地球化学表征，在S同位素数据提供的纬度信息的帮助下，提供一个独特的指纹，可用于确定大型火山喷发的潜在来源。对tephra结果的解释也将有助于了解过去火山喷发产生的火山灰的扩散（Watson et al. 2016）。一旦利用这些技术评估了过去爆发的源头位置和震级，就可以评估气候影响。这些特征对硫酸盐气溶胶在大气中的空间范围和停留时间具有很强的控制作用，从而可以评估过去火山喷发对全球气候的影响。Baroni， M.等人，2008。地球物理学报，2013(6):387 - 398。pp.D20112。Baroni， M.等人，2007。科学，315（5808）。84 - 87页。Burke， A.等人，2019。地球与行星科学通讯，521。113 - 119页。罗伯克，A., 2000。地球物理学评论，38。pp.191 - 219。Watson， E.J. et al., 2016。地球与行星科学通讯，460。pp.41-49。

The impact and frequency of large volcanic events is important to our society, with implications for global climate, governments, and industries such as aviation and agriculture. The cooling effect of volcanic sulfate aerosol emissions in the atmosphere is prolonged if the volcanic plume reaches the stratosphere and is globally circulated (Robock 2000). Therefore, having an accurate, high resolution record of past volcanism is important to understanding the frequency and climatic impact of large volcanic events which can significantly affect our society. We can understand more about the magnitude and location of large volcanic events from the ice core record, which can preserve sulfate and ash layers from local and distal eruptions (eg: Sigl et al. 2015). This continuous, high resolution ice record is therefore invaluable to the understanding past volcano-climate links. This project aims to use both sulfur isotope analysis of volcanic sulfate deposits, and geochemical characterisation of tephra shards from ice core records to determine the plume height, source volcano and climatic forcing of large eruptions from the recent geological past (<200,000 years). Multiple sulfur isotope analysis will be done using column chemistry and Multi Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Isotopic signature will help determine stratospheric or tropospheric plume height by the presence (or absence) of a mass independent fractionation (Baroni et al. 2007, 2008), and latitude of source volcano from comparison of isotopic data and SO4 concentration curves across the ice core eruption record (Burke et al. 2019). Tephra from large unknown eruptions will be geochemically characterised using Electron Probe Micro Analysis, providing a unique fingerprint that can be used to determine potential sources for large eruptions, aided by latitudinal information given by S isotope data. Interpretation of tephra results will also aid understanding of dispersal of ash from past eruptions (Watson et al. 2016). Once source location and magnitude of past eruptions are evaluated using these techniques, the climatic impact can be assessed. These characteristics have a strong control on the spatial extent and residence time of the sulfate aerosols in the atmosphere, allowing the global climatic impact of past eruptions to be evaluated.Baroni, M. et al., 2008. Journal of Geophysical Research, 113(D20). pp.D20112.Baroni, M. et al., 2007. Science, 315 (5808). pp. 84-87.Burke, A. et al., 2019. Earth and Planetary Science Letters, 521. pp. 113-119.Robock, A., 2000. Reviews of Geophysics, 38. pp.191-219.Watson, E.J. et al., 2016. Earth and Planetary Science Letters, 460. pp.41-49.