EAGER: Refining glacial lake history in Taylor Valley, East Antarctica with alternative geochronometers

EAGER：利用替代地质计时仪完善南极洲东部泰勒谷的冰川湖历史

• 批准号: 1946326
• 负责人: Peter Doran
• 金额: $ 4.53万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1946326&HistoricalAwards=false
• 关键词: EAGER; Refining; glacial; lake; history

Correlating ecosystem responses to past climate forcing is highly dependent on the use of reliable techniques for establishing the age of events (dating techniques). In Antarctic dry regions (land areas without glaciers), carbon-14 dating has been used to assess the ages of organic deposits left behind by ancient lakes. However, the reliability of the ages is debatable because of possible contamination with "old carbon" from the surrounding landscape. The proposed research will attempt to establish two alternate dating techniques, in situ carbon-14 cosmogenic radionuclide exposure dating and optically stimulated luminescence (OSL), as reliable alternate dating methods for lake history in Antarctic dry areas that are not contaminated by the old carbon. The end goal will be to increase scientific understanding of lake level fluctuation in the lakes of Taylor Valley, Antarctica so that inference about past climate, glacier, and ecosystem response can be inferred. The results of this study will provide a coarse-scale absolute chronology for lake level history in Taylor Valley, demonstrate that exposure dating and OSL are effective means to understand the physical dynamics of ancient water bodies, and increase the current understanding of polar lacustrine and ice sheet responses to past and present climatic changes. These chronologies will allow polar lake level fluctuations to be correlated with past changes in global and regional climate, providing information critical for understanding and modeling the physical responses of these environments to modern change. This research supports a PhD student; the student will highlight this work with grade school classes in the United States.This research aims to establish in situ carbon-14 exposure dating and OSL as reliable alternate (to carbon-14 of organic lake deposits) geochronometers that can be used to settle the long-disputed lacustrine history and chronology of Taylor Valley, Antarctica and elsewhere. Improved lake level history will have significant impacts for the McMurdo Dry Valleys Long Term Ecological Research (MCM LTER) site as the legacy of fluctuating lake levels of the past affects the distribution of organic matter and nutrients, and impacts biological connectivity valley-wide. This work will provide insight into the carbon reservoir of large glacial lakes in the late Holocene and have implications for previously reported radiocarbon chronologies. OSL samples will be analyzed in the Desert Research Institute Luminescence Laboratory in Reno, NV. For the in situ carbon-14 work, rock samples extracted from boulders and bedrock surfaces will be prepared at Tulane University. The prepared in situ carbon-14 samples will be analyzed at the National Ocean Sciences Accelerator Mass Spectrometry laboratory in Woods Hole, MA. The two datasets will be combined to produce a reliable, coarse scale chronology for late Quaternary lake level fluctuations in Taylor Valley.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

将生态系统的反应与过去的气候强迫相关联取决于使用可靠的技术来建立事件时代（约会技术）。在南极干燥区域（没有冰川的土地区域），碳14约会已用于评估古代湖泊留下的有机沉积物的年龄。但是，由于周围景观的“旧碳”可能污染了时代的可靠性值得商bat。拟议的研究将试图建立两种替代约会技术，即原位碳-14宇宙基因核素暴露日期和光刺激的发光（OSL），作为在不受旧碳污染的南极干燥区域中湖泊历史的可靠替代日期。最终目标是增加对泰勒河谷，南极洲湖泊湖泊波动的科学理解，以便可以推断出有关过去气候，冰川和生态系统反应的推论。这项研究的结果将为泰勒谷（Taylor Valley）的湖泊水平历史提供粗尺度的绝对年表，这表明暴露约会和OSL是了解古代水体的物理动态的有效手段，并增加对过去和现在气候变化的极地湖泊和冰盖反应的当前理解。这些时间顺序将允许极地湖泊水平的波动与过去的全球和区域气候变化相关，从而为理解和建模这些环境对现代变化的物理响应提供了至关重要的信息。这项研究支持博士生；这项研究的目的是在美国的小学课上强调这项工作。本研究的目的是建立原位碳-14暴露约会，而OSL则作为可靠的替代品（与有机湖沉积物的碳14）地球运动器，可用于定居久违的湖泊历史和泰勒谷，南方果谷，南方果酱和其他地方。改善的湖泊水平历史将对麦克穆尔多干谷长期生态研究（MCM lter）地点产生重大影响，因为过去波动湖泊的遗产会影响有机物和养分的分布，并影响范围内的生物连通性。这项工作将为全新世晚期大型冰川湖的碳储层提供洞察力，并对先前报道的放射性碳年代学有意义。 OSL样品将在内华达州里诺的沙漠研究所发光实验室进行分析。对于原位碳14的工作，将在杜兰大学准备从巨石和基岩表面提取的岩石样品。将在马萨诸塞州伍兹霍尔市的国家海洋科学加速器质谱实验室中分析制备的原位碳14样品。这两个数据集将合并为泰勒谷（Taylor Valley）中晚期湖泊水平波动的可靠，粗尺度的年表。该奖项反映了NSF的法定任务，并认为值得通过基金会的智力优点和更广泛的影响审查标准通过评估来进行评估。