Carbonate facies models
Carbonate rocks often overwhelm the untrained eye by a bewildering variety of textures, structures and grain types. Patchy diagenesis adds to the impression of almost chaotic diversity and irregularity. Upon closer inspection, the situation is not nearly as bad. If carbonate sediments are characterized by sedimentary structure, texture and grain kind, a recurring succession of facies belts can be recognized in shore-to-basin transects. These facies appear throughout the Phanerozoic and with only slight modification also in the late Precambrian. This surprising persistence indicates that the evolution of organisms in this time interval had only a modifying effect on the basic carbonate facies. The standard carbonate facies seem to capture trends dictated by other parameters such as the carbonate growth function, i.e. the distribution of growth rates as a function of depth and distance from shore, the degree of protection from waves and tidal currents, and the degree of restriction in the water exchange with the open sea. On the slopes, the declivity and the the balance between sedimentation and erosion are crucial controls. These principles are discussed in the next section, followed by a presentation of facies on ramps and rimmed platforms.
Figures & Tables
Sedimentology and stratigraphy are neighbors yet distinctly separate entities within the earth sciences. Sedimentology searches for the common traits of sedimentary rocks regardless of age as it reconstructs environments and processes of deposition and erosion from the sediment record. Stratigraphy, by contrast, concentrates on changes with time, on measuring time and correlating coeval events. Sequence stratigraphy straddles the boundary between the two fields. This book, dedicated to carbonate rocks, approaches sequence stratigraphy from its sedimentologic background. This book attempts to communicate by combining different specialities and different lines of reasoning, and by searching for principles underlying the bewildering diversity of carbonate rocks. It provides enough general background, in introductory chapters and appendices, to be easily digestible for sedimentologists and stratigraphers as well as earth scientists at large.