Kinematics of peak-ring rock deformation during cratering

揭示大撞击坑和峰环形成过程中目标岩石变形的机制和运动学构成了IODP/ICDP Expedition 364“钻探K-Pg撞击坑”的主要结构地质目标。本项目的重点是在火山口形成过程中的变形运动学，特别是从声学流化到固体的转变变形该项目的最终目标将是重建火山口和峰环形成各个阶段的目标岩石旋转。这将通过确定应变分量，特别是主应变轴的方向和剪切应变的变形结构，连续形成在陨石坑。这些构造是冲击诱发的显微构造、平面碎裂岩和超碎裂岩带以及剪切断层。对于后者，一组前所未有的602剪切断层和相关的滑动线理的钻孔岩心M0077的反演将提供信息的变形的不均匀性在最后阶段的火山口。碎裂岩和超碎裂岩带的运动学将通过使用佐贺GIS软件的定量2D图像分析和通过X射线计算机显微断层摄影术的高分辨率3D体积成像来检查。

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.