Project Details
Projekt
The role of microstructural deformation in acoustic fluidization of peak-ring target rocks of the Chicxulub impact crater
Applicant
Professor Dr. Falko Langenhorst
Subject Area
Mineralogy, Petrology and Geochemistry
Geology
Geology
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 560578952
In April and May 2016, IODP-ICDP Expedition 364 drilled and sampled the crystalline basement rocks from the peak ring of the Chicxulub impact crater on Yucatan peninsula, Mexico. While several multi-ring basins with peak rings are known from the Moon, the 200 km diameter Chicxulub structure is the only known well-preserved complex impact crater on Earth. It thus provides a unique window to the processes that act to uplift a crystalline basement during impact cratering. The upward motion of solid rocks resulted at Chicxulub in a vertical displacement of the crystalline basement by 2 – 3 km. This transport of the basement rocks is termed acoustic fluidization, i.e. a weakening of solid rocks which is commonly described by hydrodynamic flow laws. This proposal aims at understanding the deformation processes and mechanisms prevailing during the formation of a complex impact crater from a microstructural point of view. We hypothesize that the acoustic vibrations prevailing during shock propagation must have caused deformation at the grain scale, which may play an important role in lowering the friction in the target rock debris and thus enable acoustic fluidization. To test this hypothesis, we will mainly use scanning and transmission electron microscopic techniques to study the lattice defects in rock-forming minerals, which may vary from the formation of (disequilibrium) shock-metamorphic effects (such as Brazil twins and PDFs in quartz) to crystal plasticity by dislocation motion. It is equally important to examine the microchemical and microstructural characteristics of shear faults, cataclasites, and suevitic dykes, which represent sites of localized motions within the crystalline basement. Altogether, these observations are expected to provide a comprehensive understanding of the mechanics and conditions (strain rates, pressures, temperatures) of rock flow in peak rings of large impact craters.
DFG Programme
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