In the area immediately surrounding an igneous intrusion,a host limestone is locally metamorphosed to produce marble.Which of the following statements is correct?
A)The intrusive igneous rock must be older than the limestone.
B)The limestone must be older than the marble.
C)The marble must be older than the intrusive rock.
D)The relative ages of the three units cannot be determined with the information given.

Question

Quizplus · Accepted Answer

The process of metamorphism occurs after the formation of a pre-existing rock, meaning that the limestone must have been formed first. The intrusion then came later and caused localized metamorphism in the surrounding area, resulting in the formation of marble. Therefore, option B is correct. Option A is incorrect because there is no information to suggest that the intrusive rock is older. Option C is incorrect because the marble is a product of metamorphism and is therefore younger than the limestone. Option D is incorrect because the relative ages can be determined based on the sequence of events.

In the Area Immediately Surrounding an Igneous Intrusion,a Host Limestone