Metamorphic Rocks

Question 1

Metamorphic Rocks

Answer 1

Form from the change in characteristics of per-existing rocks. The changes are due to deep burial and tectonic forces (high pressure), high temperatures and the role of active fluids.

Question 2

Metamorphism

Answer 2

The solid state transformation of pre-existing rock into texturally or mineralogically distinct new rock as a result in increased temperature, pressure or both.

Question 3

Metamorphic processes

Answer 3

Thermal metamorphism
Dynamic metamorphism
Dynamothermal metamorphism

Question 4

Thermal metamorphism

Answer 4

Includes all changes produced in rock by the influence of high temperature. Development of New Minerals.
Temperature is provided by intruded magma and changes occur in the rocks close/in contact with it (contact metamorphism)
Factors that control degree of change 1. Type and temp of magma. 2. Distance from the contact. 3. Nature and composition of invaded rock.

Question 5

Metamorphic aureole

Answer 5

Large intrusion surrounded by zone of altered rock, with highest grade of metamorphism along the contacts and falling of in grade with distance.

Question 6

Thermal metamorphism produce:

Answer 6

Clayey rocks (Hydrated aluminium silicates) form new minerals that include aluminium silicates such as ANDALUSITE, CORDIERITE
Calcareous rock form WOLLASTONITE
Siliceous sandstone forms QUARTZITE
Limestone forms MARBLE

Question 7

Dynamic metamorphism

Answer 7

In simple dynamic metamorphism changes are produced by Pressure at relatively low temperature.
Pressure results from stresses as a results of earth movements. Changes are mostly structural.

Question 8

Dynamic metamorphism produce:

Answer 8

Fine grained rocks yield under high strain and develop slaty cleavage.
Shale/mudstones develop SLATES
SCHISTS are products of higher grade metamorphism than slates, and can form from same rock type.

Question 9

Schistocity

Answer 9

Involves the arrangement of platy mineral particles into roughly parallel planes as a result of rotation and re-crystallisation.

Question 10

Dynamothermal metamorphism

Answer 10

Both heat and pressure play important role. Heat is produced by geothermal gradient as rocks become more deeply buried while pressure is due to applied stress. HEAT promotes development of new minerals while PRESSURE causes deformation and development of new structures

Question 11

Metamorphic facies

Answer 11

The different grade of metamorphism and are characterized by new minerals specific to that facies due to temp and pressure conditions.