Kinematics of peak-ring rock deformation during cratering

点击翻译按钮获取中文摘要

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 K-Pg Impact Crater”.While deformation mechanisms were investigated in the previous project, the present project focuses on the kinematics of deformation during crater formation and in particular on the transition from acoustic fluidization to solid 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.