Dating the Initiation of Polar Ice Sheet Formation

极地冰盖形成起始年代的测定

• 批准号: 200992095
• 负责人: Dr. Christine Thiel
• 金额: --
• 依托单位: Leibniz-Institut für Angewandte Geophysik (LIAG)
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/200992095?language=en
• 关键词: Dating; Initiation; Polar; Ice; Sheet

Major ice sheets are one of the best climate archives on Earth, but there are at present no reliable methods for determining when these ice sheets last began to form. Such information is of great importance to verifying climate models and to other studies which make use of fossil material preserved close to the bottom of the ice (e.g., ancient DNA). Although the ice itself may not be datable, any mineral grains incorporated during initial ice build up can, in principle, be dated using luminescence techniques.In the course of the project a new luminescence method for dating the last time polar ice sheets began to form will be developed. Firstly, the suitability of recently-investigated luminescence signals from individual sand-sized grains of feldspar will be tested on ice core material. To determine the rate of energy storage from internal radioactive potassium (40K) of the individual grains both scanning electron microscopy (SEM) and laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) will be applied on the individual grains. Additionally, a new laser based spectrometry system (now under development to automatically analyse K/Na ratios in the grains) will be tested in the second phase on the project. Based on the luminescence data and the information on the internal dose rate, age estimates for the ice formation can be derived. The project will provide previously unavailable input and verification data to global climate models, and a chronological framework for the fossil record in basal ice.

大冰盖是地球上最好的气候档案之一，但目前还没有可靠的方法来确定这些冰盖最后一次开始形成的时间。这些信息对于验证气候模型和利用保存在冰底附近的化石材料的其他研究（例如，古DNA）。虽然冰本身可能无法确定年代，但原则上，在最初的冰形成过程中结合的任何矿物颗粒都可以使用发光技术确定年代。在该项目的过程中，将开发一种新的发光方法，确定极地冰盖最后一次开始形成的时间。首先，将在冰芯材料上测试最近研究的来自长石的单个砂大小颗粒的发光信号的适用性。为了确定单个颗粒内部放射性钾（40 K）的能量储存速率，将对单个颗粒应用扫描电子显微镜（SEM）和激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）。此外，一个新的基于激光的光谱分析系统（目前正在开发中，用于自动分析谷物中的K/Na比率）将在该项目的第二阶段进行测试。根据发光数据和内部剂量率的信息，可以得出冰形成的年龄估计。该项目将为全球气候模型提供以前无法获得的输入和验证数据，以及基冰化石记录的年代框架。