Impact‐related dike breccia lithologies in the ICDP drill core Yaxcopoil‐1, Chicxulub impact structure, Mexico

摘要: Petrographic descriptions of three dike breccia lithologies from drill core Yaxcopoil-1 (Yax-1) are presented. They occur within allochthonous units displaced sedimentary megablocks the Chicxulub impact structure. The suevitic breccias uppermost lithology. contain melt rock particles and injections into groundmass. Shock features ubiquitously indicate a strong thermal annealing. Flow textures suggest highly energetic emplacement process, possibly during excavation stage as ground-surge related deposit. dikes present in strongly brecciated megablock interval flow textured, anastomozing veinlets that were altered to clay minerals. impregnated dolomitic host rock, indicating low viscosity and, thus, high initial temperatures. Brecciation occurred while they still below glass transition temperature, suggesting dynamic conditions prevailed shortly after process. Major element data indicates differ composition homogenized Chicxulub. This could point an late compression or early stages cratering. clastic polymict coeval with pervasive brittle fracturing rocks. bear clasts including some crystalline basement possible fine-grained dolomite matrix turbulent textures. Fabric texture granular at ambient pressures. Such be envisaged for phase transient cavity grew fractures opened.