Impact-related melting of sedimentary target rocks of the Ru- bielos de la Cérida structure in Spain Ulrich Schüssler a , Klaudia Hradil a , Kord Ernstson b a Institut für Mineralogie der Universität Würzburg, Am Hubland, D-97074 Würzburg e-mail: uli.schuessler@mail.uni-wuerzburg.de b Fakultät für Geowissenschaften der Universität Würzburg, Pleicherwall 1, D-97070 Würzburg Abstract: The Rubielos de la Cérida impact structure forms a companion crater to the Late Eocene- Oligo- cene Azuara impact structure. Both are located more or less at the margin of the Iberian chains and the Ebro basin south of Zaragoza. Within the Rubielos structure, silicate melt rocks, carbonate-phosphate melts with small-scaled immiscibility features, very fine mixtures of silicate melt and carbonate forming clasts in suevite, as well as glassy particles of amorphous carbon were found. These melt rocks clearly reflect the chemical composition of various parts of the thick sedimentary pile in the target area and show the shock- induced high-temperature influence on these rocks. 1. Introduction The impact of the disintegrated Shoemaker-Levi 9 comet with Jupiter in 1994 was not only an exciting event for astronomers and for the impact-researcher community but has also reinforced interest in multiple impacts and multiple impact structures in our planetary system [1, 2, 3, 4, 5]. Such structures are well known from the Moon, Mars, Venus, and Jupiter's satellites Ganymed and Callisto [6, 7, 8]. On Earth, there are at least three paired craters, the West and East Clearwater Lakes, the Ries and Steinheim Basins, and the Gusev and Kamensk structures [6]. Apart from as- tronomical significance, impact cratering and ejection mechanisms of multiple impacts have been considered in order to understand, among other things, a worldwide distribution of ejecta signature possibly related with mass extinction as, e.g., at the K/T boundary [4]. Only some months ago, we provided first evidence that the previously established 35 - 40 km Azuara impact structure in Spain has a nearby companion crater of roughly equal size thus con- stituting the presently largest doublet impact structure on Earth [9, 10, 11, 12]. This newly discov- ered impact structure was named the Rubielos de la Cérida structure. Geological field work, petro- graphical investigations and geochemical analyses have provided a host of data and findings from there which have to be incorporated critically during the next time and then will be published in detail. The present paper is limited to the study of silicate, phosphate and carbonate melts as well as amorphous carbon from outcrops within the Rubielos de la Cérida structure which are important as indicators for the impact-related high temperature influence on sedimentary rocks of the target area. 2. Geological Setting 2.1. The Azuara impact structure The Azuara structure is located some 50 km south of Zaragoza at the margin between the Alpidic fold belt of the Iberian Chains and the Tertiary Ebro Basin (Fig. 1). Its impact origin was first suggested in 1985 [13] and later confirmed by detailed mapping, geophysical measurements, petrographic and geochemical studies [14, 15, 16]. According to these investigations, the most im- portant impact features are a large quantity of monomict and polymict breccias and breccia dikes, 1