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A detailed petrological study has been performed for the end-Cretaceous clastic deposits of the southern Pyrenees. Provenance results indicate that the Maastrichtian systems from both the Ager and the Vallcebre synclines show compositional features that mainly consist of a high proportion of single and polycrystalline quartz grains, feldspar and plutonic fragments. By contrast, the sandstone systems of the Tremp syncline exhibit minor contributions from igneous source areas and higher amounts of carbonatic components. These results reveal that the Tremp basin had a source area interpreted as situated to the North in the uplifting Pyrenees. The fact that this basin does not show a high plutonic source signal indicates that the Ager and the Vallcebre basins had been fed from a distinct source area located to the South, here interpreted as the Ebro Massif. Thus, the differences mentioned above might imply that the Montsec High acted as a barrier, avoiding a southern influence in the Tremp basin. |
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