Stratigraphic Plug Alignment for Integrating Plug-Based and XRF Data

Implements the Stratigraphic Plug Alignment (SPA) procedure for integrating sparsely sampled plug-based measurements (e.g., total organic carbon, porosity, mineralogy) with high-resolution X-ray fluorescence (XRF) geochemical data. SPA uses linear interpolation via the base approx() function with constrained extrapolation (rule = 1) to preserve stratigraphic order and avoid estimation beyond observed depths. The method aligns all datasets to a common depth grid, enabling high-resolution multivariate analysis and stratigraphic interpretation of core-based datasets such as those from the Utica and Point Pleasant formations. See R Core Team (2025) < https://stat.ethz.ch/R-manual/R-devel/library/stats/html/stats-package.html> and Omodolor (2025) < http://rave.ohiolink.edu/etdc/view?acc_num=case175262671767524> for methodological background and geological context.

Stratigraphic Plug Alignment (SPA)

Aligns sparse plug-based measurements (e.g., TOC, porosity, XRD mineralogy) to a high-resolution reference depth grid (e.g., HHXRF) using rule-based one-dimensional interpolation without extrapolation. Produces depth-consistent tables for stratigraphic comparison, visualization, and chemofacies/reservoir-quality analysis.