Automated core logging technology is starting to replace geologists in the core shed. Often-cited justifications for this include increased speed, multivariate sensors, and the perception that manual logging can be subjective and produces inconsistent data. An alternative is to keep the geologists and replace subjectivity with objectivity. The common practice of selecting lithology from a predetermined list of rock types can force subjective decisions. These lead to data inconsistencies that tend to increase as the rocks become progressively hydrothermally altered. A system of capture codes following the maxim, “first observe, then interpret,” is proposed as a tool to improve coding consistency and collect geologic data with greater resolution. The codes capture empirical geologic observations in a systematic and comprehensive fashion to produce a compact, computer-friendly format that facilitates data synthesis, analysis, and 3-D visualization. Capture codes do not replace any existing project or standardized company summary codes for rock types, alteration facies, or degree and style of mineralization. They capture the underlying, specific geologic observations required to make correct and consistent summary code categorizations. In other words, capture codes are empirical data, while summary codes are often subjective labels. Utilization of the codes improves the understanding of the project geology and consistency in coding between geologists, while simultaneously strengthening their field skills. After reading this article, a geologist should be able to pick up any rock and capture code the lithology and, if applicable, its alteration and mineralization as well.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.