Metamorphic Processes

Abstract

One of the basic data sets used by geologists for the geodynamic interpretation of a metamorphic terrain is the spatial and temporal evolution of pressure P, temperature T and deformation D that the rocks experienced: the metamorphic evolution of the rocks. Data on the metamorphic evolution are particularly important when interpreting ancient orogens where it is impossible to measure many other parameters directly (e.g. surface elevation, surface heat flow, gravity etc.). The relative evolution of pressure, temperature and deformation may well be illustrated as curves in P-T-space. Such curves are called P-T-paths or P-T-t-D-paths, if the path is also labeled for deformation events and time. As the interpretation of metamorphic rocks is so crucial to any geodynamic interpretation performed by a field geologist, we dedicated it here its own chapter. For detailed treatment of thermodynamics underlying all petrological studies of P-T-paths we recommend: Anderson and Crerar (1993) or: Atkins (1994). For more petrologically oriented texts with geodynamic applications we recommend: Spear (1993) or: Spear and Peacock (1989).