Depositional-Process and Diagenetic Controls on Geomechanical Properties of Carbonate Sediment-Gravity-Flow Deposits

Carbonate slope environments and their deposits exhibit highly variable depositional-element geometries and sediment distribution caused by complex transport processes (e.g., debris and turbidity flows). Carbonate particles have highly variable size, shape, and density that create complexity in reconstructing transport and depositional mechanisms with existing models developed for siliciclastic systems with more simple particle characteristics. Furthermore, the effects of diagenesis on resedimented carbonates strongly affect geomechanical behavior and complicating depositional-process interpretations. Nonetheless, there has been limited research focused on carbonate slope systems, particularly in terms of understanding the connections between deposition, diagenesis, and the resulting geomechanical properties. Using polished slab and thin section data, we quantify grain-size trends, matrix characteristics, and geomechanical properties of carbonate sediment-gravity-flow event beds. The samples were collected from two locales that represent a variety of slope sub-environments, namely the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico, and the Permian Bell Canyon Formation, Guadalupe Mountains, Texas. We specifically focus on understanding the grain size and shape distributions of carbonate clasts in a variety of deposit types, including turbidites, debrites, and hybrid event beds. We also focus on characterizing the depositional muddy matrix (where present) and diagenetic modification of matrix and clasts. Lastly, we determine the fracture intensity within the event-bed to help constrain how depositional processes and diagenesis affect the geomechanical properties. These findings have wide-reaching implications for prediction of sedimentological and geomechanical properties in conventional and unconventional hydrocarbon reservoirs globally, and to determine reservoir suitability for carbon storage, geothermal development, and other low-carbon energy projects.