The nature of the Chicxulub projectile and its distribution in the crater nd in the proximal and distal ejecta deposits: Trace element concentrations in impactites, target rocks, and potential meteoritic impactors (asteroids)

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The 2.5 km deep drill core of the ICDP "Chicxulub Scientific Drilling Project" and other formations of the ~200 km sized Chicxulub impact structure will be studied in order to reconstruct the nature of the impactor and its fate during impact by measuring the abundance of "meteoritic" elements in impact melted target rocks which are presumably "contaminated" by the projectile. This will be achieved by ICP-mass spectrometry combined with NiS fire assay procedure for the Platin Group (PGE) and other siderophile elements and by supplementary XRF and INAA analyses for major and trace elements. Two parallel subprojects will be pursued: (1) Abundance and distribution of the "meteoritic signature" in coherent impact melt rocks, suevite breccias and air fall deposits within the crater and in the proximal and distal ejecta deposits including the K/T boundary clay, and alteration effects of this signature induced by post-impact fractionation processes (crystallization, hydrothermal alteration, diagenesis), and - because of an insufficient meteorite database - (2) PGE and other siderophile element abundances (and major element composition) of the main groups and subgroups of stony meteorites (chondrites, achondrites). From the synthesis and interpretation of both data sets we expect to derive the composition of the projectile and estimates of the impact conditions (angle/velocity of impact) at the Chicxulub impact event. The results will be of general importance for a better understanding of impact processes on Earth.