Collaborative Research: Tephrochronology of a South Pole Ice Core

合作研究：南极冰芯的年代学

• 批准号: 1543454
• 负责人: Nelia Dunbar
• 金额: $ 15.52万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1543454&HistoricalAwards=false
• 关键词: Collaborative; Research; Tephrochronology; South; Pole

Dunbar/1543454Antarctic ice cores offer unparalleled records of earth?s climate back to almost one million years and perhaps beyond. Layers of volcanic ash (tephra) embedded in glacial ice can be used to establish an accurate ice core chronology. In order to use a visible or ultrafine volcanic ash layer as a time-stratigraphic marker, a unique geochemical fingerprint must be established, and this forms the basis of our research. This award will investigate the volcanic record in the 1751 m ice core that was completed at the South Pole during the 2015/16 field season. The core is in an ideal location to link the existing, established, volcanic records in East and West Antarctica, and therefore to connect and integrate those records, allowing the climate records of ice cores to be directly compared, as well as to focus research on the most widespread and significant volcanic eruptions from West Antarctica. Tephra derived from well-dated, large, tropical volcanic eruptions that may have had an impact on climate will also be studied. Recent success in identifying and analyzing very fine ash particles from these types of eruptions makes it likely that we will be able to pinpoint some of these eruptions, which will allow the sulfate peaks associated with these layers to be positively identified and dated. Volcanic forcing time series developed from earlier South Pole ice cores based on preserved sulfate were crucial for testing climate models, but without tephra analysis, the origin of these layers remains uncertain. Work on the tephra layers in the South Pole ice core has a number of significant specific objectives, some with practical applications to the basic science goals of Antarctic ice coring, and others that represent independent scientific contributions in their own right. These include: (1) providing independently dated time-intervals in the core, particularly for the deepest ice, (2) quantitatively linking tephra records across Antarctica with the goal of allowing direct and robust climate comparisons between these different parts of the continent, (3) providing information for large local eruptions, that will lead to direct estimates of eruption magnitude and dispersal patterns of Antarctic volcanoes, several of which will likely erupt again. The initial stages of the work will be carried out by identifying silicate-bearing horizons in the ice core, using several methods. Once found, silicate particles will be imaged so that morphological characteristics of the particles can be used to identify volcanic origin. Particles identified as tephra will then be chemically analyzed using electron microprobe and laser ablation ICP-MS. Samples that yield a robust chemical fingerprint will be statistically correlated to known eruptions, and this will be used to address the goals described above. Broader impacts of this project fall into the areas of education of future generation of researchers, outreach and international cooperation. These activities will continue to promote forward progress in integrating the Antarctic tephra record and more broadly tying it to the global volcanic record.

邓巴/1543454南极冰芯提供了地球上无与伦比的记录--S，气候可以追溯到近百万年前，甚至更久。嵌入冰川冰中的火山灰层(Tephra)可以用来建立准确的冰芯年代学。为了利用可见或超细的火山灰层作为时间地层标志，必须建立唯一的地球化学指纹，这构成了我们研究的基础。该奖项将调查2015/16年度在南极完成的1751米冰芯中的火山记录。冰芯位于一个理想的位置，可以将南极东部和西部现有的既定火山记录联系起来，从而连接和整合这些记录，从而能够直接比较冰芯的气候记录，并将研究重点放在南极洲西部最广泛和最重要的火山爆发上。还将研究来自日期准确的大型热带火山喷发的Tephra，这些火山喷发可能对气候产生了影响。最近在识别和分析这些类型喷发的非常细的火山灰颗粒方面取得的成功，使我们很可能能够精确定位其中的一些喷发，这将使与这些层相关的硫酸盐峰得到肯定的识别和日期测定。以保存的硫酸盐为基础的早期南极冰芯形成的火山强迫时间序列对气候模型的测试至关重要，但如果没有tephra分析，这些层的来源仍然不确定。南极冰芯中的特弗拉层的工作有许多重要的具体目标，其中一些是对南极冰芯的基础科学目标的实际应用，另一些则本身就是独立的科学贡献。这包括：(1)提供核心的独立日期时间间隔，特别是最深的冰；(2)将整个南极洲的冰盖记录定量地联系起来，以便能够直接和有力地比较大陆这些不同部分的气候；(3)为当地的大规模喷发提供信息，这将导致对南极火山喷发规模和扩散模式的直接估计，其中几个火山可能会再次喷发。这项工作的初始阶段将通过使用几种方法识别冰芯中的硅酸盐岩层来进行。一旦发现，硅酸盐颗粒将被成像，这样颗粒的形态特征就可以用来识别火山起源。然后，将使用电子探针和激光消融电感耦合等离子体质谱对被鉴定为Tephra的颗粒进行化学分析。产生强大化学指纹的样本将从统计上与已知喷发相关，这将用于实现上述目标。该项目的更广泛影响涉及下一代研究人员的教育、外联和国际合作。这些活动将继续推动在整合南极特弗拉记录和更广泛地将其与全球火山记录联系起来方面取得进展。