Project Details
Projekt Print View

Mechanisms of target-rock deformation during peak-ring formation

Subject Area Palaeontology
Term from 2017 to 2021
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 343434615
 
Final Report Year 2021

Final Report Abstract

Crater floors of large terrestrial impact structures, also known as impact basins, are largely flat and dissected by two or more morphological rings. The formation of the innermost ring, the socalled peak ring, and causes of target rock weakening leading to flat crater floors are still unknown. Unravelling these mechanisms were the prime structural geological objectives of Expedition 364 “Drilling the K-Pg Impact Crater” and this project using the Chicxulub impact structure, Mexico, as a terrestrial analogue for the formation of planetary impact basins. The project furnished structural geologic proof for the validity of the acoustic fluidization hypothesis formulated more than 40 years ago by the late H. Jay Melosh. This hypothesis calls for a transient fluid-like behaviour of impacted rock during cratering, which enabled the formation of impact craters, hundreds of kilometres in diameter, within less than 10 minutes. Project results not only identified the respective rock deformation mechanism that weakened the rock; the results also explain, for the first time, the presence of flat crater floors dissected by central peaks and morphological rings. Furthermore, the project revealed also unprecedented evidence for the interaction of molten rock, which covered the crater floor immediately after cratering, with rock-debris laden seawater entering the crater within about an hour after impact. Finally, micro-tomography demonstrated that impacted rock contains up to 13% of open pores, which seem to be connected to each other by small channels. These results have important ramifications for the possible origin of life in large impact craters on the Early Earth and other planets. In summary, we contributed significantly to our understanding on the formation mechanisms of large impact craters and their peak rings, the dynamics of impact melt and physical state of rocks forming the peak rings. Numerous press releases, reports and (live) interviews on TV and Radio took up the results of our project.

Publications

 
 

Additional Information

Textvergrößerung und Kontrastanpassung