Deforming the Earth

We are interested in the conditions and history of deformation during metamorphism over a wide range of conditions in different tectonic settings: for example, in high- and ultrahigh-pressure terrains that contain migmatites (crystallized partially molten rocks, typically dominated by quartz + feldspar) and eclogite (high-pressure metamorphosed basalt) and in the shear zones that form in metamorphic core complexes and gneiss domes. There is interesting information about deformation and metamorphic history in the major minerals (quartz in migmatites, clinopyroxene in eclogites) and minor minerals (zircon, rutile, and titanite in both). We determine the microstructure and composition of minerals in the context of the field relations of the host rock.

The STAMP group investigates these processes by field-based studies (currently or recently: the Western Gneiss Region of Norway; metamorphic core complexes of the North American Cordillera). We have been investigating deformation histories using field and analytical methods, including integrating pressure-temperature-time (P-T-t) and deformation information; i.e., “petrochronology” (P-T-t) + deformation.

key topics: shear zones, mylonites, petrochronology, pressure-temperature-time-deformation history