Accretion of Extraterrestrial Matter to the Earth: The Sedimentary Record

拟议的研究计划将在以下方面取得重大进展： 了解的化学和矿物学记录的 地外物质对地球的吸积， 陆地沉积物 在接下来的三年里，我们建议研究 从矿物学和地球化学的碎片从三个不同的 影响事件。 1)我们将描述丰富的， 第三系界线的分布和组成 太平洋盆地的撞击碎片。 这将大约 以这种方式研究的地球表面部分增加一倍， 可能会导致迄今为止最权威的研究， 这些碎片的组成。 2)我们将详细调查 早太古代（~3.4 Ga）球粒床的地球化学， 一次主要的小行星撞击以及地壳构造的重大变化 巴伯顿绿岩带的演化 我们将集中 在确定是否有地球化学证据支持 关于小球床的等级反映了化学物质的假说 以及撞击产生的蒸汽云的热演化。 3)我们 计划对新沉积物和碎片记录进行初步定性 一颗小行星撞击南太平洋， 上新世晚期 沉积物将来自活塞芯， 计划于1994年1月取样。

The proposed research program will make major advances in the understanding of the chemical and mineralogical record of the accretion of extraterrestrial matter to the Earth, as recorded in terrestrial sediments. In the next three years we propose research into the mineralogy and geochemistry of debris from three distinct impact events. 1) We will characterize the abundance, distribution, and composition of Cretaceous-Tertiary boundary impact debris in the Pacific Ocean basin. This will approximately double the portion of the Earth's surface studied in this way and will probably result in the most definitive study to date of the composition of this debris. 2) We will investigate the detailed geochemistry of an early Archean (~3.4 Ga) spherule bed which marks a major asteroid impact as well as a major change in the tectonic evolution of the Barberton Greenstone Belt. We will concentrate on determining whether there is geochemical evidence to support the hypothesis that gradations across the spherule bed reflect chemical and thermal evolution of an impact-generated vapor cloud. 3) We plan initial characterization of new sediments and debris recording an asteroid impact into the subantarctic South Pacific during the late Pliocene. The sediments will be from piston cores that are scheduled for sampling in Jan. 1994.//