Engineering Geology Multiple Choice Questions on “Structures of Metamorphic Rocks – 01”.
1. Which is the structure with extremely fine rock mass?
a) Cataclastic structure
b) Schistose structure
c) Gneissose structure
d) Maculose structure
Answer: a
Clarification: Cataclastic structure is characterized by the development of extremely fine rock mass under the influence of severe crushing and shearing effects operating during metamorphism.
2. Give an example for a rock with cataclastic structure.
a) Schist
b) Marble
c) Slate
d) Augen gneiss
Answer: c
Clarification: The effect of shearing and crushing in the metamorphic rocks undergone metamorphism can be observed in rocks spread over wide areas. Rocks like crush breccia, mylonite and slate show this type of structure.
3. Structure involving flaky or rod-like structures is ______________
a) Cataclastic structure
b) Schistose structure
c) Gneissose structure
d) Maculose structure
Answer: b
Clarification: The rock with schistose structure is made up of broadly parallel or sub-parallel layers or bands of flaky, platy or rod-like minerals making it very weak in the direction of parallelism.
4. The structure which also has flaky appearance and bands other than schistose is ____________
a) Cataclastic structure
b) Schistose structure
c) Gneissose structure
d) Maculose structure
Answer: c
Clarification: In gneissose structure. Bands or folia of platy and flaky minerals alternate with those of equidimensional and granular minerals.
5. Gneissose is indicative of advance degree of metamorphism.
a) True
b) False
Answer: a
Clarification: The gneissose texture is indicative of an advance degree of metamorphism under combined action of high temperature, high pressure and active participation of fluids.
6. Structure involving porphyroblasts is ____________
a) Cataclastic structure
b) Schistose structure
c) Gneissose structure
d) Maculose structure
Answer: d
Clarification: Maculose structure is characterized by a spotted appearance of the rock that may be caused due to the formation of large-sized crystals called porphyroblasts within an otherwise fine grained rock.
7. The structure similar to maculose is __________
a) Cataclastic structure
b) Schistose structure
c) Augen structure
d) Maculose structure
Answer: c
Clarification: Augen structure is broadly similar to maculose type and is typical of metamorphic rocks in which the effects of crushing under pressure are clearly associated with recrystallization.
8. Which structure has lens-like shaped structure?
a) Cataclastic structure
b) Schistose structure
c) Augen structure
d) Maculose structure
Answer: c
Clarification: In augen structure, some resistant minerals get deformed into thin, lenticular, lens like shapes giving a characteristic appearance to the rock.
9. The metamorphic rocks showing granulose structure is __________
a) Gneiss
b) Slate
c) Schist
d) Marble
Answer: d
Clarification: Granulose structure is a typical structure of metamorphic rocks like marble and quartzite and is characterized by an essentially granular character of the constituent minerals.