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

陨石撞击在演化过程中发挥了重要作用 早期太阳系的行星表面 本 记录了地球早期的撞击历史， 类地行星主要来自对月球岩石的研究 和弹坑 主要研究者迄今进行的研究 巴伯顿绿岩中的独特球粒层 带提供了大量证据，证明它们是远端的一部分 巨型陨石产生的喷出物和冷凝层 在32到35亿年前撞击地球。 这些 沉积物提供了关于影响的直接信息来源 力学、撞击碎片产生的过程、 分散和积累的最后阶段的陆地 和行星吸积。 这些早太古代远源岩的厚度比较 碎片毯，通常为30至50厘米的几乎纯 球粒，含白垩纪末界球粒和粘土 表明太古代的撞击规模巨大 一定对早期的陆地生物产生了深远的影响 沉积和生物系统。 的目的 拟议的研究计划是通过实地和 实验室研究这些影响的性质。

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.