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Can Morphometric Patterns in Modern Carbonate Platforms be Applied to the Ancient Rock Record? Insights from Modern Alacranes Reef and Upper Palaeozoic Carbonate Platforms


In recent years, considerable research has been undertaken in order to gain a better quantitative understanding of morphometric patterns within modern carbonate depositional systems. The industrial application of the scaling/juxtaposition relationships derived from the modern to subsurface Cenozoic carbonate reservoirs appears relatively straightforward, given that many key biota are common to both. However, the direct application of modern sedimentary insight further back into the geologic rock record is more controversial, given the enormous changes in the biota, climate, sea-level, water chemistry, and so on, that have taken place. To justify such an approach, we contend that similar morphometric patterns should be observed in both the modern and ancient data. In the Norwegian Barents Sea, numerous seismic surveys have imaged Upper Palaeozoic carbonate buildups arranged in polygonal networks, or reticular patterns. These patterns are observed in both warm and cool water buildups, and are developed atop platforms founded on stable shelves, in tectonically active settings, and platforms developed over basinal evaporites. GIS mapping of multiple seismic horizons allows the Palaeozoic reticulated morphology to be numerically compared to that mapped in Alacranes from QuickBird satellite imagery. QuickBird's meter-scale resolution allows identification of subtle cross-platform trends, such as windward-leeward differences in the packing density of ridge-and-pond complexes, which can be correlated with the kilometer-scale patterning extracted in the Barents subsurface. Despite different controls, and architecture, the patterning of reticulated networks is statistically inseparable between the two systems, once the meter-scale Modern dataset is re-sampled to seismic resolution. While other controls cannot unequivocally be ruled out, these results suggest that biotic self-organization is a fundamental driver of sedimentary patterns on carbonate platforms. To our knowledge, this is the first quantitative comparison of morphometric patterns from the Modern and Palaeozoic that clearly reveals similar patterns of self-organization. For the depositional environments considered, the findings suggest that juxtaposition rules, facies proportions, and scaling relationships harvested from the modern can successfully be applied to the ancient.