Ocean Drilling Perspectives on Meteorite Impacts

Extraterrestrial impacts are a ubiquitous process in the solar system, reshaping the surface of rocky bodies of all sizes. On early Earth, impact structures may have been a nursery for the evolution of life. More recently, a large meteorite impact caused the end-Cretaceous mass extinction, causing the extinction of 75% of species known from the fossil, including non-avian dinosaurs, and clearing the way for the dominance of mammals and eventual evolution of humans. Understanding the fundamental processes associated with impact events is critical to understanding the history of life on Earth, and the potential for life in our solar system and beyond.
Scientific ocean drilling has generated a large amount of unique data on impact processes. With the constant subduction and creation of oceanic crust, the Chicxulub impact is the single largest and most significant impact event that can be studied by sampling modern ocean basins. Marine sediment cores have been instrumental in quantifying the environmental, climatological, and biological effects of that impact. Drilling in the Chicxulub Crater has significantly advanced our understanding of fundamental impact processes, notably the formation of peak rings in large impact craters, but also raised new questions waiting to be addressed with further drilling. Within the crater, the nature and thickness of the melt sheet in the central basin is unknown, and an expanded Paleocene hemi-pelagic section would provide insights to both the recovery of life and the climatic changes after the impact. Globally, new cores in the Pacific could directly sample the downrange ejecta of this northeast-southwest trending impact.
Extraterrestrial impacts have been controversially suggested as primary drivers for many important paleoclimatic and environmental events throughout Earth History. However, marine sediment archives and geochemical proxies (e.g., Osmium isotopes) provide a long-term archive of major impact events in recent Earth history and show that, other than the end-Cretaceous, significant environmental changes do not appear to be driven by impacts.

外星撞击是太阳系中普遍存在的现象，重塑了各种大小岩石天体的表面。在地球早期，撞击结构可能是生命演化的摇篮。近期，一次大型的陨石撞击导致了白垩纪末的大规模灭绝，导致75%的已知化石物种灭绝，包括非鸟类恐龙，并为哺乳动物的统治和人类的最终演化铺平了道路。理解与撞击事件相关的根本过程对于理解地球生命的历史以及我们太阳系乃至更远星系中生命的可能性至关重要。科学海洋钻探产生了大量关于撞击过程独特的数据。随着海洋地壳的持续俯冲和形成，奇克舒卢布撞击事件是可以通过采样现代海洋盆地研究的最单一、最重大的撞击事件。海洋沉积岩心在量化该撞击事件的环境、气候和生物效应方面发挥了关键作用。在奇克舒卢布撞击坑的钻探显著提高了我们对基本撞击过程的理解，特别是大撞击坑中峰值环的形成，但也提出了需要进一步钻探才能解决的问题。在撞击坑内，中央盆地熔岩层的性质和厚度尚不清楚，扩大始新世的半深海沉积层将为撞击后生命的恢复和气候变化提供洞见。在全球范围内，太平洋的新岩心可以直接采样东北-西南走向撞击事件的远端喷射物。有争议地提出，外星撞击是地球历史上许多重要古气候和环