1. What four important physical parameters are found to increase with depth duri

Question

1. What four important physical parameters are found to increase with depth during tectonic burial to

control the changes in texture and mineral composition associated with regional burial metamorphism?

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2. Identify the following metamorphic rock types based on their descriptions:

   a. a fine grained frosty looking mono-mineralic rock mass with

no observable foliation and a hardness of H7.               ______________

   b. a greenish fine-grained well-foliated rock with a distinctive sheen

on the foliation surface but with no visible macroscopic minerals.      _______________

   c. a medium-grained somewhat sparkly mono-mineralic rock mass

with no observable foliation and a hardness of H3.                _____________

   d. a medium-grained rock mass of alternating layers of dark colored amphibole and

light-colored feldspar/quartz showing signs of deep plastic flow deformation. ­ _____________

   e. a very fine-grained aggregate of very cleavable rock material with

a well-developed planar fabric.                       _____________

   f. a medium-grained aggregate of muscovite and biotite with a preferred

orientation that defines a strong planar fabric.              ______________

   g. a variably-textured mix of small scale intrusive granites and residual foliated

       metamorphics representing the site of deep crustal melting.            ______________

3. Match the protolith in the left column to the appropriate metamorphic equivalent in the right column.

a. micritic limestone

b. medium-grained diorite

c. olivine gabbro

d. pure quartz sandstone

e. pebbly arkose

g. clay-rich shale

i. pegmatitic granite

____ marble

____ slate

____ black & white gneiss

____ porphyroclastic gneiss

____ metaconglomerate

____ quartzite

____ serpentinite

4. Name three different kinds of mica, distinguished by their color, that form the typical metamorphic rock

“schist” with its foliation defined by the parallel alignment of these sheet silicates?

5. a. What is the difference between the porphyroblastic texture that is common to many metamorphic

rocks and the porphyroclastic texture that is restricted to rocks involved in crustal shear zones?

   b. Name one porphyroblastic mineral found in the schists?

   c. Name one porphyroclastic mineral found in shear zones through granitic rocks?

d. What rock type would be found in these crustal shear zones?

6. a. Name a specific metamorphic rock type formed from a shale protolith that suggests lower grade

metamorphic conditions at shallow levels in the crust?

   b. Name a metamorphic index mineral that would be found in these lower-grade rocks that reflects this

low level of burial and metamorphism.

   c. Name a specific metamorphic rock type formed from a shale protolith that suggests higher grade

metamorphic conditions from deep in the crust?

   d. Name a metamorphic index mineral that would be found in these higher-grade rocks given the right

initial composition?

7. a. What kind of metamorphic rocks are found in northern Maine:

low grade (shallow depth of burial) or high grade (deeper depths of burial) metamorphic rocks?

   b. Considering your answer above, would you really expect to find actual sedimentary limestone in

      Limestone, Maine?

8. a. What is the time of peak metamorphism in the Maine section of the Northern Appalachians (when the mountain crust was at its thickest due to collision during the Acadian orogeny)?

(# of millions of years ago. ………and ………………geologic time period).

   b. Where would you go to find the most highly-sheared mylonitic metamorphic rocks in Maine??

Explanation / Answer

1. a) low temperature

b) low pressure

c) high temperature

d) high pressure

2) a) quartzite

b) slate

c)marble

d)gneiss

e)phyllite

f)schist

e)migmatite

3) a-black & white gneiss

b-serpentinite

c-marble

d-quartzite

e-metaconglomerate

g-slate

i-porphyroclastic gneiss

4) 1.mica

2.biotie

3.muscovite

5)  porphyroblast is a large mineral crystal in a metamorphic rock which has grown within the finer grained groundmass

but during metamorphism, porphyroblasts may grow before, during, or after the phase of deformation recorded by the matrix minerals

a)  garnet

b)garnet

6)a)slate

b)chlorite

c)gneiss

d)sillimanite

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