THERE AND BACK AGAIN: AN INQUIRY-BASED TEACHING MODULE FOR EXPLORING SUBDUCTION ZONE METAMORPHISM

Subduction zones hold a key role in the Earth’s geochemical cycles by transporting volatiles, especially water, from the surface to the planet’s interior and driving a range of important geological processes. Although commonly covered in undergraduate geology courses, most departments lack a suite of subduction metamorphism samples (blueschists, eclogites), especially lawsonite-bearing rocks owing to their rare preservation. We developed a teaching module consisting of hand samples and thin sections of four different lawsonite-bearing rocks from Sivrihisar, Türkiye, to offer a hands-on, inquiry-based learning experience for Petrology and Earth Materials courses. Twenty institutions, spanning from research universities to small colleges, taught the module during a lab session and participated in the student assessment. Another ten institutions received samples but were not assessed. In addition to samples, instructors received a set of core questions containing embedded assessment questions. Optional parts of the modules also provided additional questions; supplementary information covering general subduction zone metamorphism, an overview of lawsonite and its significance, and regional tectonics of the Sivrihisar area; as well as further geochemical data of samples (bulk-rock, mineral composition) and relevant references. Student responses (n=200) overall indicate the module not only enhanced their ability to identify and describe mineral assemblages and textures as well as infer the pre-subduction parent rock, but also enabled them to construct different stages of metamorphic history based on a synthesis of observations and interpretations. Modifications to the module include updating a question about metamorphic history that seemed to be difficult for students and developing an online version of the module. Our module emphasizes the importance and usefulness of well-characterized samples from well-defined tectonic domains to create inquiry-based learning opportunities for students.