5. Consider a felsic composition magma that cools at depth. a. What type of rock

Question

5. Consider a felsic composition magma that cools at depth.

a. What type of rock will be formed? How would you describe its texture?

b. How would its texture be different if it had cooled at Earth’s surface? Why?

c. What minerals comprise this type of rock? Include at least 4 examples.

d. Describe a tectonic event that could expose this rock at the surface (illustrated as region A in the sketch below).

e. Give a detailed explanation of at least three processes likely to be involved in changing this rock (at A below) into sediments.

f. Describe two agents for transportation of these sediments that will carry the rock toward B.

g. How will sediment characteristics change from the source (A) to the edge of the continent (D) (e.g. with increasing transportation away from source)?

h. Describe how the sediment in location D is turned into sedimentary rock. Include at least three processes that are necessary for lithification, what type of rock will be produced at various distances offshore, and why.

Explanation / Answer

A felsic magma has an abundance of SiO2 (quartz) so it will form silica saturated or oversaturated minerals like quartz, plagioclase feldspar, muscovite, biotite etc. therefore the rock will be granitic in composition. as the magma cools at depth it will cool slowly and have sufficient time to form large coarse grained euhedral to subhedral crystals. so the texture of the rock will be interlocking (as it is igneous rock crystallizing from a melt) euhedral coarse grained granite.

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.