CSDMS 2016 annual meeting poster JeremyKerr
Investigating the relationship between carbonate facies belts and mosaics
Abstract:
The spatial patterns of facies within a carbonate depositional system provide a geologic record of climatic and oceanographic conditions. The classic textbook model describes such a system as a series of shore- or margin-parallel facies belts whose occurrence strongly correlates with water depth. While clearly useful for describing broad-scale spatial patterns and reconstructing geologic history, including sea-level curves, the belt model does not adequately capture the fine-scale spatial heterogeneity of facies arrangements observed in real-world systems. This limitation of the belt model led to the proposal the facies mosaic model as an alternative description for carbonate depositional systems. A facies mosaic is defined as, “an arrangement of lithological elements lacking significant linear trends in element arrangement, but showing some statistically significant relationship between element size and frequency of occurrence.” This definition is a useful starting point for refining our understanding of these sedimentary systems, yet it too is limited. In particular, there is an implicit assumption that belt systems and mosaics are distinct end-members on a spectrum of possible facies configurations, yet it remains unclear whether this assumption is true or not. Further muddling the issue is the fact that facies belts can exhibit the statistically significant relationship between element size and frequency of occurrence inherent to the mosaic model. Thus, there is a need to revisit these two models to better understand their relationship to address the aforementioned issues. This is important because if they do represent distinct configurations, then one must ask if they represent different sets of environmental controls. If they do, then the criteria for distinguishing the two endmembers require refinement to ensure reliable interpretation of the sedimentary record. This study investigates the relationship between the belt and mosaic models using real-world observations of lateral facies patterns from a modern isolated carbonate platform.
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