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Structural features in the Azuara impact structure

Peculiar structural features in Dogger limestones (rim region, Barranco de Bocafóz, Almonacid de la Cuba). More often than with tectonics, structural features in impact structures may reflect strong tensile forces (as shown here) due to rarefaction following the passage of shock waves.

Unusual joint pattern, unfamiliar to structural geologists, in the Azuara impact structure (between Moneva and Moyuela villages; outcrop height about 5 m): Conjugate sets of strongly curved joint surfaces cut the Jurassic limestones into bars of approximately rhomboidal cross-section (pencilled for enhancement). The strike direction of the curved sets as well as those of similar sets in several other outcrops roughly point to the center of the impact structure. Probably, the sets have resulted from impact-induced dynamic stress modulation of running fractures during the excavation flow (see model in Müller & Ernstson 1990).

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