INTEGRATING FIELD, GEOCHEMICAL AND GEOPHYSICAL DATA IN UNDERGRADUATE COURSES TO ILLUSTRATE PLATE TECTONICS

Making connections between plate tectonic processes that occur at depth and the rocks that crop out at the surface presents a major conceptual hurdle for many undergraduates. Because students cannot see these processes occurring in “real time,” they are challenged to comprehend how these processes occur. Students also have difficulty reconciling how data collected at the outcrop-scale informs geologists of global-scale processes. To address these conceptual hurdles, this abstract presents an example of the successful integration of field, geochemical and geophysical data to enhance learning in a 200-level course on plate tectonics. Although the data collected and themes discussed are local to the institution, these strategies can be adapted and exported to any location.

Students devote a 3-hour lab period to examining two mafic dikes that crop out in the Casco Bay Region of Maine. At both locations, students identify minerals, determine the range of crystal sizes and measure the orientation of each dike. For their lab write-up, students synthesize their field data, propose multiple working hypotheses for how the dikes formed and state what data they would need to distinguish among their hypotheses.

In a follow-up class section, students use Pb isotopic data to establish a geochemical fingerprint of one of the dikes. Students then revisit their hypotheses and formulate a revised framework that integrates both field and geochemical data. By comparing Pb isotopic data from a variety of settings, students determine that their Pb isotopic data and the orientation of both dikes are consistent with the Central Atlantic Magmatic Province (CAMP). Students then use geophysical data to assess the volume and spatial distribution of mafic rocks associated with CAMP. From this context, students connect CAMP to the break-up of Pangea and the formation of the North Atlantic Ocean basin.

Throughout this process, students analyze field, geochemical and geophysical data. By working with multiple datasets, students learn that the integration of data collected from a range of techniques allows them to “see” processes at a variety of time- and length-scales, ultimately enabling them to draw connections between local outcrops and global tectonic processes.