HR: 0800h
AN: P41A-0225    [Abstracts]
TI: Chemical Aspects of the Impact Process
AU: * Daly, T
EM: terik.daly@gmail.com
AB: Impact cratering plays an integral role in the evolution and formation of planetary systems. Chemical anomalies are accepted phenomena at impact sites, but few, if any, published models adequately describe the kinetics and thermodynamics of impact-induced chemical changes. Utilizing XRF, ICP-MS, GDMS,and SHIRMP-RG, this study analyzed the trace chemical composition of shock- metamorphosed granite and obtained quantitative data, which were further analyzed using parametric frequentist statistics and resampling techniques. The concentrations of Cu, Ni, Pb, Zn, Rb, and Sc changed in a statistically significant manner at the 99% confidence level. Based on chemical and thin section analyses, a cohesive model was developed to describe how impact-induced chemical changes form. As the impactor collides with the target material, most of the impactor melts. As the shock waves and subsequent rarefaction waves move through the target, partial melting of mineral phases begins. Material from the impacting body combines with the partial melt, thereby amalgamating an extraterrestrial component into the target. Characteristics of the amalgamation process are related to the partitioning coefficients, ionic radii, ionic charges, and electron configurations of the involved components. Ongoing work focuses on the determination of the relationship between chemical composition and proximity to interstitial boundaries.
DE: 1060 Planetary geochemistry (5405, 5410, 5704, 5709, 6005, 6008)
DE: 3672 Planetary mineralogy and petrology (5410)
DE: 5420 Impact phenomena, cratering (6022, 8136)
DE: 6022 Impact phenomena (5420, 8136)
DE: 8136 Impact phenomena (5420, 6022)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting