The Effects of Large Impacts on Early Archean Depositional Systems and Biological Communities

陨石撞击在早期太阳系行星表面的演化中起了重要作用。目前对地球和类地行星早期轰击史的记录主要来自对月球岩石和陨石坑的研究。迄今为止，首席研究员对巴伯顿绿岩带岩石中独特的球体层的研究提供了大量证据，证明它们是32亿至35亿年前巨大陨石撞击地球时产生的远端喷出物和冷凝物毯的一部分。这些沉积物提供了关于撞击力学、撞击碎片产生、分散和积聚的过程以及陆地和行星增生的最新阶段的直接信息来源。将这些早期太古代远端碎屑毯（通常为30至50厘米的纯球体）与白垩纪末期边界球体和粘土层的厚度进行比较，表明太古代的冲击规模巨大，对早期陆地沉积和生物系统产生了深远的影响。拟议研究计划的目的是通过实地和实验室研究来评估这些影响的性质。

Meteorite impacts played a fundamental role in the evolution of planetary surfaces in the early Solar System. The present record of the early bombardment history of the Earth and terrestrial planets derives largely from studies of lunar rocks and cratering. Studies to date by the principal investigator of distinctive spherule layers in rocks of the Barberton Greenstone Belt provide substantial evidence that they are parts of distal ejecta and condensate blankets produced by giant meteorite impacts on the Earth 3.2 to 3.5 billion years ago. These deposits provide a direct source of information on impact mechanics, the processes by which impact debris is generated, dispersed and accumulates and the latest stages of terrestrial and planetary accretion. Comparison of the thickness of these Early Archean distal debris blankets, commonly 30 to 50 cm of virtually pure spherules, with terminal Cretaceous boundary spherule and clay layers suggests that the Archean impacts were of enormous size and must have had profound effects on early terrestrial depositional and biological systems. The objective of the proposed research program is to evaluate through both field and laboratory studies the nature of these effects.