Evaluation of controls on carbonate platform morphology, facies and diagenetic variability: An Oligocene example from southeast Spain

A thick succession of Rupelian (Early Oligocene) shallow-water carbonates in southeast Spain is the subject of this study. These outcrops are unique, as there is a global rarity of exposed shallow-water Oligocene carbonates. The Oligocene is significant, as it was a time of global cooling, accompanied by changes in biotic assemblages and sedimentation patterns. This particular platform existed on the former Iberian continental margin at a time when the tectonic regime had changed from compressional to extensional. Within the context of a changing global and tectonic environment, this dissertation addresses the controls on morphology, facies belts, and diagenesis of Oligocene shallow-water carbonate platforms, and also evaluates the stable isotope ratios of red algae as a proxy of early diagenesis.; Tectonics controlled the platform morphology and facies succession, and the strata show much evidence for extension. The platform had a steep-sided, possibly faulted, shelf margin that resulted in large blocks deposited downslope. The Rupelian strata at the Costa Blanca onlap a Cretaceous to Eocene basement, show an overall deepening-upward succession, and are capped by a major unconformity (Late Oligocene strata are missing). The succession evolved from semi-restricted to open marine facies, also attesting to the increased subsidence resulting from extension.; The biotic succession appears to have been controlled by water temperature. The upper portion of the succession clearly exhibits a cool water signature. In particular, it consists of a cool water biotic assemblage, and the diagenesis involved little marine cementation, but much compaction and collapse of components.; The stable isotope ratios of red algae are thought to be good paleoclimate indicators. In general, though, the stable isotope ratios of modern algae show much variability. The stable isotope ratios of the algae from the Costa Blanca show both lateral and vertical variability. This variability is not clearly facies or genera related. The algae have been neomorphosed, however, and much of this variability probably reflects the heterogeneity of the pore water chemistry during dissolution and precipitation. The overall coarser change from more negative to more positive δ13C values within the succession, however, may actually be a modified reflection of global ocean chemistry.