On the fate of the projectile in impact cratering experiments

Identification of meteoritic projectile matter as either chemical trace or physical remnant is the only way to assess the past impactor population related to the terrestrial impact record. Projectile traces occur in impact melt rocks and breccias, fractures in the crater floor, or as distal ejecta. However, the physical conditions during emplacement, modes of target-projectile mixing, and possible fractionation are not well constrained. The current project as part of the MEMIN Research Unit will address these problems under defined experimental conditions: Target (sandstone) and projectile (iron meteorite, steel with tracer elements) compositions will be chosen such that strong chemical differences will enable (i) unambiguous identification of small particles and minute condensates of the projectiles, and (ii) constraining relative contributions of target/ projectile to mixtures. We will survey where, and in which quantities projectile matter occurs in, beneath, and around the crater, making use of highsensitive and high-precision geochemical techniques. The study addresses fundamental topics in impact cratering, i.e., (i) projectile partitioning into spall-material, ejecta, and sub-crater basement, and (ii) the possibility of inter-element fractionation in projectile matter which is critical with regard to chemical classification of projectile traces.

Principal Investigators
Hecht, Lutz Dr. (Details) (Geoscientific Labs)

Duration of Project
Start date: 06/2009
End date: 05/2012

Last updated on 2020-20-03 at 23:06