THE EVOLUTION OF THE MIDDLE TRIASSIC (MUSCHELKALK) CARBONATE RAMP IN THE SE IBERIAN RANGES, EASTERN SPAIN - SEQUENCE STRATIGRAPHY, DOLOMITIZATION PROCESSES AND DYNAMIC CONTROLS

The Upper Permian-Triassic strata of the SE Iberian Ranges, eastern Spain, display the classic Germanic-type facies of Buntsandstein, Muschelkalk and Keuper. The Muschelkalk is represented by two carbonate units with a siliciclastic-evaporitic unit in between. Their ages range from Anisian to basal Carnian (Middle Triassic to base of the Upper Triassic). The carbonate units represent ramps that evolved during the early thermal subsidence period which succeeded the first rift phase. Seven facies have been distinguished, representing shoals, tidal flats, organic buildups and lagoons, as well as a karst horizon in the lower carbonatic unit. Most of the carbonates were dolomitised. Three processes of dolomitization are invoked: mixing waters, penecontemporaneous seepage refluxion, and deep burial. The top of the Buntsandstein and the Muschelkalk facies are subdivided into two depositional sequences, including lowstand, transgressive and highstand systems tracts, with superimposed tectonic and eustatic controls.