Triassic rocks of the Iberian Range consist of a succession of continental sandstones (Buntsandstein), peritidal carbonates and shales (Muschelkalk), and continental claystones and evaporites (Keuper).

Dolostone, which comprises 75% of Muschelkalk

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carbonates, bears no relation to sedimentary facies; to the contrary, it is demonstrably joint-controlled. This evidence, together with the near absence of "dedolomite," indicates a late and sustained source of magnesium in excess of that expected from an evaporite-bearing assemblage.

Water samples from Keuper "salinas" (salt-producing evaporating pans) show that meteoric water descending through the Keuper evolves into a brine with Mg:Ca ratios locally 4:1, despite the abundance of gypsum and anhydrite. Samples of Keuper subjected to simple solution in the laboratory liberate Ca:Mg in the ratio of 3:2, which is probably sufficient for dolomitization under reasonable subsurface temperature-salinity conditions. X-ray analysis indicates chlorite as a source of the magnesium, the solubility of which probably reflects diagenetic fixing in the Keuper evaporite basin. The composition of Keuper water, aided prior to unloading by geothermal gradient, is thought to be responsible for Muschelkalk dolomitization.

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