CHEMOFACIES, CORE-SCALE ELEMENT MAPPING, AND THE LINKAGES BETWEEN MINERALOGY, ROCK FABRIC, AND ESTIMATED ROCK STRENGTH IN TWO MUDSTONE SUCCESSIONS (Invited Presentation)
Geochemical and micro-rebound hammer (MRH) characterization of mudstone-dominated strata within the Devonian-Mississippian-aged Bakken Formation (Williston Basin, MT) and the Early Permian-aged Wolfcamp Formation (Midland Basin, TX) are interpreted along with element-mineral model outputs that, underpinned by X-ray diffraction (XRD) results, help define the underlying mineralogical controls. For simplification purposes, it is initially assumed that element-mineral linkages made at one scale hold true at finer scales, and that MRH-based estimates of unconfined compressive strength (UCS) made at the mm scale are transferable to other scales. A chemofacies assignment approach based on grouping samples collected at the facies scale outlines key intervals for more detailed elemental mapping that is used to evaluate sub-facies-scale variability and characterize rock fabric. Ultimately, testing and refinement of the linkages between mineralogy, rock fabric, and rock strength of these strata sheds light on technique limitations and the scales of mudstone heterogeneity.