Impact-related melting of sedimentary target rocks of the Rubielos de la Cérida structure in Spain
Project management at the University of Würzburg:
Within the Iberian Chains west of Zaragoza, the new impact structur of Rubielos de la Cérida was recently detected several tens of kms beside the well established Azuara impact structure. Both impact structures were formed about 30 million years ago and therefore are assumed to represent a double impact. The geology of the target area is strongly dominated by sedimen-tary rocks which behave completely different from crystalline target rocks. As components in various impact breccia of the Rubielos de la Cérida structure, different melt rocks were found. Silicate melt rocks occur as dm-wide inclusions in the breccia and consist of loosely welded sphaeroidal or irregularly formed glass particles. Other samples show amoebae-like carbonate droplets swimming within a phosphate matrix which in part is glassy and in part recrystallized apatite. The carbonate droplets are interpreted as quench products of a former carbonate melt, immiscible with a coexisting phosphate melt. Melt rocks with similar texture are also de-scribed from the Nördlinger Ries and the Haughton crater. Very fine-grained glassy particles are dispersed in components of a suevite-like impact rock, as shown by x-ray diffraction analysis. At least, very hard and slag-like particles of amorphous carbon (+oxygen) were found, which most probably result from a reduction process of carbonate target rocks in the course of the impact.
Projekt period: since 01.1998