Paleosols in shallow marine carbonate sequences

Abstract

Shallow water carbonate sequences in the geological record commonly exhibit numerous exposure surfaces reflecting emersion of sediment due to progradation processes and sealevel oscillations. Some ancient platform sequences contain hundreds of such surfaces, associated with paleosols (fossil soils), typically calcretes. A wide range of macro- and microstructures are associated with these calcretes which are reviewed. Profile types and stages in profile development can be defined. The nature of the exposure surface and associated paleosols can be used to identify the nature of the prevailing climate, although hydromorphic effects related to marine flooding of the platforms can modify the paleosols. A potentially important use of paleosols is to define the nature of sequence boundaries; several studies have identified sets of paleosols with varying maturities reflecting changes in rates of accommodation space creation during sealevel rises and falls.