ANSWER CHECK FOR METAMORPHIC ORIGIN: OBSERVED AND INFERRED

Describe one structural change that accompanies increasing metamorphism in the vicinity of a large intrusive igneous body. HINT: Look at the diagram showing structural changes with metamorphism. Follow the changes that occur within an originally horizontal layer.
Describe two textural changes that accompany increasing metamorphism in the vicinity of a large intrusive igneous body. HINT: Look at the series of micro-textural drawings. What happens to grain size? What happens to grain orientation? What happens to an originally clastic texture?
Explain under what circumstances melting is a by-product of changes that cause metamorphism. HINT: Review Plate Tectonic Scenario 2.
In a sedimentary wedge caught between converging plates, increases in T and P may cause some rock types to metamorphose whilst others actually melt.
Explain under what circumstances the presence of a melt causes the changes that result in metamorphism. HINT: Review Plate Tectonic Scenario 3.
Where melts form above a descending plate and then rise into overlying crust, the rocks there may be metamorphosed by the intruding melts.

© 2001, David J. Leveson