Kyte 9418303 It is proposed to continue the broad-based research program which is designed to make significant advances in the understanding of the chemical and mineralogical record of extraterrestrial matter to the Earth, as recorded in terrestrial sediments. We propose research into the mineralogy and geochemistry of debris from three distinct impact events. (1) In the next three years our principal objective will be a renewed investigation of a unique deposit that we discovered. It records an asteroid impact into a deep-ocean basin during the late Pliocene. Will join a German polar research expedition in Spring 1995 that will engage in a geophysical and geological exploration of the region in which the impact occurred. Sediment cores recovered that contain debris from the impact will be the subject of mineralogical and geochemical analyses to learn about the physical and chemical evolution of this impact event as well as to use it as an analog to Cretaceous-Tertiary boundary deposits. (2) We will also investigate the detailed geochemistry of an early Archean (-3.4 Ga) spherule bed which may record 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) Additionally we will characterize the abundance, distribution, and composition of Cretaceous-Tertiary boundary impact debris in sediments from the Atlantic and Indian Oceans. This will approximately double the portion of the Earth's surface studied in this way greatly improve our model of the evolution and distribution of impact debris relative to the Chicxulub structure. (4) We also anticipate that we will be requested to provide Ir analyses for other researchers. As our schedule permits, we will assist in such problems, if appropriate.
