Collaborative Research: Investigating Geochemical Signatures in Greenland ice of a Possible Extraterrestrial Impact During the Younger Dryas Climate Event

合作研究：调查新仙女木气候事件期间可能受到外星影响的格陵兰冰的地球化学特征

• 批准号: 1417476
• 负责人: Paul Mayewski
• 金额: $ 3.36万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1417476&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Geochemical; Signatures

The primary objective of the proposed research is to obtain records of platinum, iridium, and osmium concentrations and osmium isotope ratios in the GISP2 Greenland ice core in order to investigate the hypothesis that there was a meteorite or comet impact at the onset of the Younger Dryas abrupt climate event 12,900 years ago. These analyses will be combined with high-resolution measurements of climate proxies obtained on the same samples. Osmium isotopes have the potential not only to conclusively confirm or refute the presence of an extraterrestrial impact, but also to provide information about the size and type of the impactor, should one be confirmed. High-resolution analyses of the atmospheric circulation proxies sodium, calcium, and iron represent a leap in ice core analysis resolution from one sample per three years to over 100 samples per year. The proposed research activities would contribute towards an understanding of what happened at the Younger Dryas, which will be of broad interest to geologists, geochemists, climatologists, archeologists, astronomers, and the general public. Following recent reports of a large anomaly in platinum concentration in the GISP2 ice core, four investigators propose a series of collaborative analyses at Dartmouth College and the University of Maine on GISP2 ice core samples of Younger Dryas age to: (1) evaluate the platinum spike at the Younger Dryas onset for potential contamination and contributions from volcanic and terrestrial sources, (2) measure osmium concentration and isotope composition to evaluate whether an impact occurred at the Younger Dryas onset and assess the nature of any impactor, and (3) assess the environmental change across this critical climate transition by measuring iron, sodium and calcium at storm-scale resolution using a new laser ablation mass-spectrometry system. The proposed research will provide students with opportunities for engaged learning in order to increase their interest and knowledge of how geochemical investigations provide insights to climate change affecting the Arctic. In particular, this study will constitute a major portion of a Ph.D. thesis and an undergraduate Senior Thesis. It will expose graduate and undergraduate students to cutting-edge geochemical and mass spectrometric techniques.

拟议研究的主要目标是获得 GISP2 格陵兰冰芯中铂、铱和锇浓度以及锇同位素比的记录，以调查新仙女木期开始时存在陨石或彗星撞击的假设12,900年前的突然气候事件。这些分析将与在相同样本上获得的气候代理的高分辨率测量相结合。锇同位素不仅有可能最终证实或反驳外星撞击的存在，而且如果得到证实，还可以提供有关撞击物大小和类型的信息。对大气环流代理钠、钙和铁的高分辨率分析代表了冰芯分析分辨率的飞跃，从每三年一个样本到每年 100 多个样本。拟议的研究活动将有助于了解新仙女木事件发生的情况，这将引起地质学家、地球化学家、气候学家、考古学家、天文学家和公众的广泛兴趣。最近有报道称 GISP2 冰芯中铂浓度存在较大异常，四名研究人员提议在达特茅斯学院和缅因大学对新仙女木时代的 GISP2 冰芯样本进行一系列合作分析，以：(1) 评估铂峰值在新仙女木期爆发时，了解火山和陆地来源的潜在污染和贡献，(2) 测量锇浓度和同位素组成，以评估新仙女木期爆发时是否发生影响并评估任何撞击物的性质，以及（3）通过使用新型激光烧蚀质谱系统以风暴规模分辨率测量铁、钠和钙，评估这一关键气候转变期间的环境变化。拟议的研究将为学生提供参与学习的机会，以提高他们对地球化学调查如何提供影响北极的气候变化见解的兴趣和知识。特别是，这项研究将构成博士学位的主要部分。论文和本科生高级论文。它将让研究生和本科生接触最先进的地球化学和质谱技术。