Facies Architecture and Mechanical Stratigraphy of Carbonate Slope Systems: Case Study of the Mississippian Crinoidal Fan System of the Doña Ana Member of the Lake Valley Formation, Sacramento Mountains, New Mexico

Carbonate slope systems form an important part of carbonate platform-to-basin transitions in all settings throughout the Phanerozoic. Lower-slope strata of the Doña Ana Member form an excellent analog to producing lower slope hydrocarbon reservoirs utilizing non-matrix (fracture) porosity. This study combines a sedimentological process-based approach to characterizing the nature of carbonate slope deposits and fracture network characterization, with the aim to link depositional processes to the mechanical properties of carbonate slope depositional elements to predict the distribution of fractures. Preliminary data from one of the measured section sites reveal three distinct assemblages: 1)granule-sized rudstone-dominated, 2) Very coarse sized grainstone-dominated, and 3) wackestone-mudstone-dominated. Grainstones and rudstones are observed in massive non-graded beds interpreted as bedload transport deposits. Rudstones form dominantly tabular bed geometries, whereas grainstones and wackestones form non-tabular bed geometries with scour features at their base. Two primary depositional elements are interpreted: 1) Element 1 comprises non-tabular beds rich in grainstones and less dominant basal-scoured wackestones, representing deposition in channel axis and margin settings, respectively, and 2) Element 2 is characterized by gravel-rich tabular units, which could be deposited in either a channelized setting or in the proximal region of an unconfined lobe complex. The geometry, spatial extent and depositional processes of Element 2 are important attributes, as we preliminarily observe fracture intensity to be qualitatively higher in Element 2 than in Element 1. Additional data will further characterize the geometries and architectures of these two elements and establish fracture genetic relationships between fractures and depositional processes.