Ecospace variability along a carbonate platform at the northern boundary of the Miocene reef belt (Upper Langhian, Austria)

Abstract

The south-western edge of the Leitha Mountains in the southern Vienna Basin (Austria) exposes parts of an Upper Langhian (Middle Badenian) shallow water (<30m) carbonate platform. The study of its ecospace comprises sedimentological and palaeontological data of 4 up to 36m thick carbonate sections of the Müllendorf quarries which have been logged and subjected to detailed investigation and sampling. The sedimentary record is dominated by coralline algal debris sands which represent 7 distinct lithofacies (bioclastic coralline algal-mollusc facies, Hyotissa facies, Isognomon facies, coral facies, rhodolith facies, bryozoan facies). All these facies are described in detail in respect to lithology and biota and are palaeoecologically interpreted. Striking features of these limestone successions are periodical intercalations of coral- and mollusc-rich horizons. Their formation had been triggered by water turbidity and low amplitude changes in relative sea level. These relations are especially interesting as the platform carbonates formed at the northern edge of the Langhian Peri–Mediterranean reef belt. Water turbidity, as ecological master factor, and depth played the fundamental role in ecosystem and community expression within ecospace. The lateral distribution and the ecological relations between the various facies types allow proposing an ecospace-occupation model.