Study Guide for Metamorphic Rocks

Practical

1. Be able to identify hand samples of common metamorphic rocks.
2. Be able to identify the protolith of hand specimens of common metamorphic rocks.
3. Be able to calculate a chemical composition from a mode and a set of analyses of phases in a rock.
4. Be able to identify reasonably well in hand sample all minerals in common metamorphic rocks >1 mm across.
5. Be able to recognize and identify all minerals in thin section that you saw in the Metamorphic Minerals Lab.
6. Be able to interpret mineral inclusions and other textures in terms of a sequence of reactions, and be able to identify mineral assemblages seen in thin section on appropriate ternary phase diagrams.

Theoretical

1. Be able to accurately calculate the temperature and pressure at any depth being given the depth, rock density, geothermal gradient, and surface temperature.
2. Be able to sketch a reasonably accurate Pressure-Temperature-time path for a rock during metamorphism if given a set of P and T estimates at various times, or if given a series of tectonic events (that is, trace the P-T-t path of the rock).
3. Be able to show schematically the phase relations on unary, binary, and ternary phase diagrams.
4. Understand the nature of continuous and discontinuous reactions. Be able to schematically show each of these reaction types on binary and ternary phase diagrams.
5. Know how to make graphical projections of phase diagrams, and the reasons for making them.
6. Understand the concept of metamorphic isograds and know some of the more common ones.
7. Know the approximate P-T areas occupied by different metamorphic facies (characterized by rock types: chlorite schist, amphibolite, eclogite, etc.) and metamorphic grades (characterized by mineral assemblages in common bulk compositions such as the assemblage sillimanite-muscovite-K-feldspar).
8. Understand and be able to explain the stress-strain curves of brittle faults and the two types of ductile faults, and the effect each type of fault would have on fault width.
9. Be able to use an appropriate petrogenetic grid (a P-T diagram showing reaction lines) to determine the range of P and T that any particular assemblage could have formed in.
10. Know the definitions of common geological terms (make a list of those that you don't understand that come up in class or in readings.