Hit or miss - Meteorite impacts in the Cretaceous Western Interior Sea: Sedimentological and paleoecological response

成败——陨石对白垩纪西部内海的影响：沉积学和古生态反应

• 批准号: 217037-2012
• 负责人: SchroderAdams, Claudia
• 金额: $ 1.97万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=523668
• 关键词: Hit; miss; Meteorite; impacts; Cretaceous

The Western Interior Sea bordered by the Rocky Mountains to the West and the Canadian Shield to the East was a dynamic epicontinental sea covering Western North America during the Cretaceous Period marked by global high sea levels. Throughout the Cretaceous the seaway's paleogeographic boundaries varied significantly. Marine communities responded to fluctuating paleoecological conditions that were driven by paleoceanographic and paleogeographic changes (opening and closing of faunal migration routes), substrate and oxygen variations. In areas of low sediment supply such as the eastern margin of the basin coarser grained intervals within extensive shale packages are often recognized by their high concentration of phosphatic vertebrate debris forming bioclastic layers. The origin of these bioclastic horizons or bonebeds, some of them recognized basinwide, has been explained as wave erosional surfaces or transgressive lag deposits. We hypothesize that some of these bonebeds are the result of tsunami deposits that were generated by two meteorites that either directly hit the Western Interior Seaway or landed in close proximity. These are the Steen River Crater in Alberta dated 91 MA and the Deep Bay Crater in Saskatchewan dated 99 MA. Biotic responses to a catastrophic event will be investigated by looking at several fossil groups including vertebrate assemblages, foraminifera, calcareous nannofossils and dinoflagellates. Methods will include detailed petrographic and geochemical analysis in the search of meteorite impact indicators (shocked quartz, tektites etc.), taphonomic studies of vertebrate remains, and high resolution microfaunal analysis in order to bracket these events. Our studies in the Western Interior Sea will distinguish between those horizons that form important sea level related, basin-wide sequence boundaries serving for wireline log correlations and more random event beds. Recent tsunami events on earth will be extensively studied for their impact on ecological systems. Consequently, recognition of ancient tsunami deposits, their extent and impact on basin ecology and marine life forms becomes an exciting endeavor.

西部的西海与西部的落基山脉接壤，东部的加拿大盾牌是一个充满活力的e东向海，覆盖了西部北美西部，在全球高海平面标志着的白垩纪。在整个白垩纪，海道的古地理边界都有很大的变化。海洋群落对由古文化和古地理变化（动物迁移路线的开放和关闭），底物和氧气变化驱动的古生态条件的波动作出了反应。在低沉积物供应区域，例如在广泛的页岩包装中的盆地较粗糙的间隔的东边边缘通常通过其高浓度的磷酸脊椎动物碎屑形成生物塑料层来认识到。这些生物碎屑范围或骨床的起源（其中一些被识别的盆地都被识别为波浪侵蚀表面或侵蚀性滞后沉积物。我们假设其中一些骨床是由两个陨石产生的海啸沉积物的结果，这些陨石要么直接撞到西部内部海道，要么是近距离降落。这些是艾伯塔省（Steen River Crater）的日期为91 Ma的Steen River火山口，萨斯喀彻温省的深湾火山口日期为99 Ma。通过查看包括脊椎动物组合，有孔虫，钙质纳米化石和鞭毛鞭毛的几个化石组，将研究对灾难性事件的生物反应。方法将在搜索陨石冲击指标（震惊的石英，tektites等），脊椎动物遗迹的taphonomic研究以及高分辨率的微孔分析中，包括详细的岩石学和地球化学分析，以括起来这些事件。我们在西海内部的研究将区分那些形成重要海平面，盆地范围内的重要海平面的视野，用于有线对数相关性和更多随机事件床。将对地球上最近的海啸事件进行广泛研究，以实现其对生态系统的影响。因此，对古代海啸矿床的认识，其对盆地生态和海洋生物形式的程度和影响成为一项令人兴奋的努力。