Petrographic and geochemical evidence for an allochthonous, possibly impact melt, origin of pseudotachylite from the Vredefort Dome, South Africa

Hypotheses proposed to explain the origin of pseudotachylite bodies formed during impact cratering include: (1) frictional heating, (2) shock loading, (3) decompression or (4) drainage of impact melt into target rocks. In order to differentiate among these processes, we conducted detailed geochemical and petrographic analysis of the matrices in pseudotachylitic veins and dikes and of their respective wall rocks. Our analyses indicate that the …