Rubielos de la Cérida impact structure (Spain): Impact-induced internal rock polish.

Image A shows part of an extended megabreccia deposit in the southern central uplift of the Rubielos de la Cérida impact structure. Within a chaotic accumulation of limestone blocks and fragments, a large surface displaying prominent striae and polish occurs (hammer length 40 cm). Any relation to tectonic structures is clearly missing. It is assumed that the peculiar deformations formed in the highly compressive process of the central uplift development (modification stage of impact cratering).  A
 B An internal polish of strongly brecciated rocks is abundantly observed in the Rubielos de la Cérida structure; see Image B: mirror polish in a grit-brecciated megaclast of the Barrachina megabreccia.