George Davis | Active Tectonics as Integrative Capstone in Teaching Structural Geology

Though the sequence of presentation varies widely from instructor to instructor, fundamental topics covered in the teaching of undergraduate structural geology are basic descriptions of structures, displacement and strain, deformation mechanisms, material behavior, force and stress, structural associations, and tectonics. It might be argued that “the making of structures” has historically been a relative weakness in the pedagogy of structural geology.

Most examples used in the classical teaching of structural geology have focused on ancient structures in ancient mountain belts because of factors related both to history of geology and geologic history, including investigations of oil and mineral provinces.  But without illuminating examples of structures forming today, there can be too great a gap between stress analysis or strain analysis or experimental metaphors and the creation of structures.   Even though the origin of structures resides so commonly in plate tectonics, plate tectonics may not necessarily be covered at all in structural geology classes, for a whole variety of practical reasons and false assumptions.

Active tectonics can illuminate “the making of structures” in real time.   GPS “tracking” of plate motions calls out whole fields of displacement vectors and deformation paths, including rates of motions.   “Deformation” can be “seen” through comparison of initial and final locations of individual points, changes in orientation of bodies, and changes in shapes of whole regions.  Individual structures, and systems of structures, can be viewed in the context of actively deforming milieu of which they are a tiny part.  Relationships between, e.g., folding and faulting can be grasped through the integration of geodetic measurements of changing topography, focal mechanisms for earthquakes, and 3D mapping of earthquake storms of seismic action.  In situ stress orientation data, and well chosen seismic reflection profiles, help to round out the picture.  Opportunities for creative pedagogy abound.  For example, the sequencing of examples of ‘active tectonics’ will vary considerably from instructor to instructor:  active tectonic scenarios (theatre!) can be interspersed along the way, or can ‘cap off’ the course in ways the reveal the ‘punch line’ of what is forcing structures to form.

[Davis, G.H., and Reynolds, S.J., 2004, Active tectonics as integrative capstone in teaching
Structural geology:  Geological Society of America Abstracts with Programs, v. 36, no. 5, p. 348.]