Beschreibung
Unravelling the mechanisms and kinematics of target rock deformation during large-impact cratering and peak-ring formation constitute the prime structural geological objectives of IODP/ICDP Expedition 364 “Drilling the KPg Impact Crater”. While deformation mechanisms were investigated in projects Ri 916/16-1, 2, the focus of this project will be on the deformation kinematics during cratering and on the transition from acoustic fluidization to solid-state deformation. The ultimate goal of the project will be to reconstruct target rock rotation during individual stages of crater and peak-ring formation. This will be accomplished by identifying strain components, notably the orientations of principal strain axes and shear strains of deformation structures that formed consecutively during cratering. The structures are shock-induced microstructures, planar cataclasite and ultracataclasite zones, and shear faults. As to the latter, inversion of an unprecedented set of 602 shear faults and associated slip lineations of drill core M0077 will provide information on the heterogeneity of deformation during the latest stage of cratering. The kinematics of cataclasite and ultracataclasite zones will be examined by quantitative 2D image analysis using the software SAGA GIS and high-resolution 3D volumetric imaging through X-ray-computed microtomography.