Age spectra of zircon and related phases from impactites of late Triassic meteorite impact structures and their ejecta deposits

晚三叠世陨石撞击结构及其喷射物沉积物撞击岩中锆石及相关相的年龄谱

• 批准号: 52363829
• 负责人: Dr. Axel Wittmann
• 金额: --
• 依托单位: Department of Earth Sciences
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/52363829?language=en
• 关键词: Age; spectra; zircon; related; phases

This proposal aims to investigate late Triassic (Norian) meteorite impact structures. Zircons from impactites of three impact structures will be analyzed by the Sensitive High-Resolution Ion Micro-Probe (SHRIMP) technique: Manicouagan (100 km Ø), Saint Martin (40 km Ø) and Rochechouart (23 km Ø). Provenance analyses based on characteristic age spectra of zircons from the different craters’ impactites and target rocks will be used to investigate their contribution to distal ejecta deposits. A test for the existence of a global ejecta layer that corresponds to the formation of the Manicouagan impact crater will be undertaken at Norian sections in British Columbia, in the Fundy basin of Nova Scotia, Canada, and in Southwest Britain. A detailed study of shock-metamorphosed zircons and related polymorphs, using transmission electron microscopy and micro-Raman spectroscopy, will complement the study in order to refine the U-Pb dating technique as applied to impact events. Primary goals of this study are the establishment of a method for the identification of distal impact-ejecta deposits and the refinement of the dating of these events. The identification and analysis of such critical marker horizons will refine the stratigraphic record of meteorite impacts on Earth and unravel their potential environmental effects.

这项建议旨在研究晚三叠世(诺利安)陨石撞击结构。来自三个撞击结构的撞击物中的锆石将用灵敏的高分辨率离子微探针(SHRIMP)技术进行分析：马尼古阿根(100公里直径)、圣马丁(40公里直径)和罗切霍瓦特(23公里直径)。基于来自不同陨石坑撞击岩和目标岩石的锆石的特征年龄谱的物源分析，将被用来调查它们对远端喷流沉积的贡献。将在不列颠哥伦比亚省的诺里安地区、加拿大新斯科舍省的芬迪盆地和英国西南部进行一项与马尼古阿根陨石坑形成相对应的全球喷射层存在的测试。利用透射电子显微镜和显微拉曼光谱对受冲击变质的锆石和相关多晶型进行详细研究，将是这项研究的补充，以完善应用于撞击事件的U-Pb测年技术。这项研究的主要目标是建立一种识别远端撞击喷射物沉积的方法，并改进这些事件的年代测定。这种关键标志层位的识别和分析将完善陨石对地球影响的地层记录，并揭示其潜在的环境影响。