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

西部内海（英语：Western Interior Sea）是一个活跃的陆表海，在白垩纪期间覆盖北美西部，以全球高海平面为标志，西面与落基山脉接壤，东面与加拿大地盾接壤。在整个白垩纪，海道的古地理边界变化很大。海洋群落对古海洋学和古地理学变化（动物群迁移路线的开放和关闭）、基质和氧气变化所驱动的波动的古生态条件作出反应。在沉积物供应量低的地区，如盆地东部边缘，广泛的页岩包内的粗粒间隔通常通过其高浓度的磷酸盐脊椎动物碎屑形成生物碎屑层来识别。这些生物层位或骨层的起源，其中一些被认为是全盆地的，被解释为波浪侵蚀面或海侵滞后沉积。我们推测，这些骨床中的一些是由两颗陨石直接击中西部内陆航道或在附近降落所产生的海啸沉积物的结果。这些是阿尔伯塔的斯廷河陨石坑，年代为公元91年，萨斯喀彻温省的后海湾陨石坑，年代为公元99年。生物对灾难性事件的反应将通过观察几个化石组来研究，包括脊椎动物组合、有孔虫、钙质超微化石和腰鞭毛虫。方法将包括在寻找陨石撞击指标（冲击石英、玻璃陨石等）时进行详细的岩相学和地球化学分析，对脊椎动物遗骸进行埋藏学研究，并进行高分辨率微型动物群分析，以确定这些事件。我们在西部内海的研究将区分那些形成重要的海平面相关的、用于电缆测井相关性的全盆地层序边界的层位和更多的随机事件层。将广泛研究最近发生在地球上的海啸事件对生态系统的影响。因此，认识古代海啸沉积物，其范围和对盆地生态和海洋生物形式的影响成为一项令人兴奋的奋进。

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.