Vesicles in an igneous rock are evidence for which of the following?
A) a highly felsic composition
B) degassing of volatiles
C) fractional crystallization
D) magma mixing

Question

Quizplus · Accepted Answer

Vesicles are small holes or bubbles in rocks which indicate that gas (volatiles) was present in the magma during the solidification process. As the magma cools, the gas escapes and leaves behind the voids in the rock, resulting in vesicles. Therefore, vesicles are evidence of degassing of volatiles.

Vesicles in an Igneous Rock Are Evidence for Which of the Following