Facies Architecture and Mechanical Stratigraphy of Mississippian Carbonate Sediment Gravity-Flow Deposits: Rancheria Formation, Sacramento Mountains, New Mexico

Carbonate slope deposits are of considerable scientific importance, economic significance, and academic interest, but remain understudied in terms of depositional processes, facies architecture, fracture distribution, and the resultant mechanical stratigraphy. Outcrops of the Rancheria Formation in the Sacramento Mountains, New Mexico represent a Mississippian carbonate slope system that is spectacularly exposed for sedimentologic and fracture characterization. Using these outcrops, this study establishes a correlation between facies architecture, depositional processes, and fracture parameters (e.g., length, height, aperture, intensity).

We define mechanical stratigraphic units that are strongly influenced by the sedimentological properties of sediment gravity-flow deposits, as well as the stacking patterns that create architectural elements (e.g., channel elements). Vertical and lateral variability in mechanical stratigraphy is observed at multiple scales in the Rancheria Formation, from individual beds (<1 m thick) to element/complex scale (~1 km wide).

Preliminary observations suggest a relationship between fracture characteristics and distributions (e.g., fracture intensity and fracture dimensions ratios) and gravity-flow facies. Specifically, this study signifies the alternations of packages composed of various facies within the outcrops along three sections, and examines their respective mechanical response by collection of fracture characteristics (length, height, aperture) and distribution along numerous scan lines. The results of this study provide critical insights applicable to reservoir modeling of conventional hydrocarbon reservoirs and induced-fracture propagation in unconventional reservoirs, and also refine the understanding of deep-water resedimented carbonate deposits and their similarities/differences from siliciclastic systems.