USING INTEGRATED PETROLOGIC, GEOCHEMICAL, AND MINERALOGICAL DATASETS IN UNDERGRADUATE CLASS PROJECTS

Solutions to fundamental geological questions often require observations and evidence that must be integrated over numerous spatial and temporal scales, and using data from many independent sources. This commonly presents challenges in the pre-professional training of geologists. A case study approach using diverse geological datasets is used in a junior-level undergraduate igneous and metamorphic petrology course for students to a) engage a research-like experience in class, b) address a question of contemporary geologic interest, and c) develop scientific habits of the mind. Data from a suite of plutonic rocks from the Archean Lake Plateau area of the Beartooth Mountains are used to address the question, What is the petrogenesis of these granites? Students initially participate on a field trip to the area (weather permitting), and have access to geologic maps, images of the area, hand samples, and thin sections. Students can also have access to additional information in the form of whole-rock and trace element analyses, isotopic (Rb-Sr, Nd-Sm, U-Pb), and mineral composition data--but only after they ask appropriate questions, and describe how these data will be useful in interpreting the rocks. Standard plotting routines (e.g. Harker diagrams, elemental discriminant plots, isotopic plots, etc.) are used to render and display the data. A metamorphic exercise on the Cherry Creek Metamorphic Suite, Gravelly Range, MT, is focused on the metamorphic history of these rocks, including integration of textural (deformation) analysis, interpretation of equilibrium assemblages vs. polymetamorphic overprints, geothermobarometry, and thermochronology towards creation of a PTt path. In both cases, an integrative report is required, assessed for evidence of mastery of geologic concepts, selection and presentation of data and other supporting evidence, and internal consistency of the interpretations.